<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with Wdesk from Workiva-->
<!--Copyright 2022 Workiva-->
<!--r:33d870a3-6b97-4bdc-8e32-aba6533b0bec,g:6ab57a0b-7565-47e4-8385-0eecb1b7f8e4-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:roleRef roleURI="http://powersint.com/role/CONSOLIDATEDBALANCESHEETS" xlink:type="simple" xlink:href="psix-20211231.xsd#CONSOLIDATEDBALANCESHEETS"/>
  <link:calculationLink xlink:role="http://powersint.com/role/CONSOLIDATEDBALANCESHEETS" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_bfa3517a-76e1-4db0-a6c6-173f02eab082" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LinesOfCreditCurrent_4df43732-b126-44d6-9422-59430e9cf7af" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LinesOfCreditCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_bfa3517a-76e1-4db0-a6c6-173f02eab082" xlink:to="loc_us-gaap_LinesOfCreditCurrent_4df43732-b126-44d6-9422-59430e9cf7af" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_a4375801-ca3f-47bf-b154-1ae4ebc587a3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_bfa3517a-76e1-4db0-a6c6-173f02eab082" xlink:to="loc_us-gaap_LongTermDebtCurrent_a4375801-ca3f-47bf-b154-1ae4ebc587a3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherShortTermBorrowings_8070b5ef-c14c-4d78-87b9-641a0eb64bec" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherShortTermBorrowings"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_bfa3517a-76e1-4db0-a6c6-173f02eab082" xlink:to="loc_us-gaap_OtherShortTermBorrowings_8070b5ef-c14c-4d78-87b9-641a0eb64bec" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent_f77b6877-1c46-4589-83a2-28af10c43705" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountsPayableCurrent"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_bfa3517a-76e1-4db0-a6c6-173f02eab082" xlink:to="loc_us-gaap_AccountsPayableCurrent_f77b6877-1c46-4589-83a2-28af10c43705" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAccruedLiabilitiesCurrent_a2744856-70fe-423f-921f-3e499d01ec98" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherAccruedLiabilitiesCurrent"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_bfa3517a-76e1-4db0-a6c6-173f02eab082" xlink:to="loc_us-gaap_OtherAccruedLiabilitiesCurrent_a2744856-70fe-423f-921f-3e499d01ec98" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_fc69f909-ef9c-43a5-b063-9a5c24120b10" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Assets"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_14c5cd28-2f7f-4b09-8095-ef5cbe108a9c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AssetsCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_fc69f909-ef9c-43a5-b063-9a5c24120b10" xlink:to="loc_us-gaap_AssetsCurrent_14c5cd28-2f7f-4b09-8095-ef5cbe108a9c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_7f11ec57-b060-49dd-b586-6459b6273d63" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_fc69f909-ef9c-43a5-b063-9a5c24120b10" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_7f11ec57-b060-49dd-b586-6459b6273d63" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_96e01856-dce2-4179-b55f-0e5d028ef61c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_fc69f909-ef9c-43a5-b063-9a5c24120b10" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_96e01856-dce2-4179-b55f-0e5d028ef61c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_b1b76e53-552a-4419-a821-ae9d739b8b09" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Goodwill"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_fc69f909-ef9c-43a5-b063-9a5c24120b10" xlink:to="loc_us-gaap_Goodwill_b1b76e53-552a-4419-a821-ae9d739b8b09" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_7825822d-66bb-4012-9af1-52be26fe0143" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherAssetsNoncurrent"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_fc69f909-ef9c-43a5-b063-9a5c24120b10" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_7825822d-66bb-4012-9af1-52be26fe0143" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_8d035742-a649-4fcd-80c2-766d6206f5f6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockValue_efbeb45b-af0e-41e0-b2ef-7aa47234ab93" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PreferredStockValue"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_8d035742-a649-4fcd-80c2-766d6206f5f6" xlink:to="loc_us-gaap_PreferredStockValue_efbeb45b-af0e-41e0-b2ef-7aa47234ab93" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_5e496532-50b8-4c45-89ff-3a1dcb55ad37" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockValue"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_8d035742-a649-4fcd-80c2-766d6206f5f6" xlink:to="loc_us-gaap_CommonStockValue_5e496532-50b8-4c45-89ff-3a1dcb55ad37" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapital_e08cafd5-37e2-4821-a23e-4d46a376d1c2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdditionalPaidInCapital"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_8d035742-a649-4fcd-80c2-766d6206f5f6" xlink:to="loc_us-gaap_AdditionalPaidInCapital_e08cafd5-37e2-4821-a23e-4d46a376d1c2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_c7a5ae6f-4417-406f-b8fc-b3ffbd309103" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_8d035742-a649-4fcd-80c2-766d6206f5f6" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_c7a5ae6f-4417-406f-b8fc-b3ffbd309103" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValue_b139be15-41bd-490a-9da9-fdeb82be17b7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TreasuryStockValue"/>
    <link:calculationArc order="5" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_8d035742-a649-4fcd-80c2-766d6206f5f6" xlink:to="loc_us-gaap_TreasuryStockValue_b139be15-41bd-490a-9da9-fdeb82be17b7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_9fdee22d-8c83-4f57-909a-ba031993d3e3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_5ef79e8f-cb8e-4330-8cce-11c9d72d7df5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Liabilities"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_9fdee22d-8c83-4f57-909a-ba031993d3e3" xlink:to="loc_us-gaap_Liabilities_5ef79e8f-cb8e-4330-8cce-11c9d72d7df5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_9d349988-9f65-4c72-a06e-1d7ca09100ab" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockholdersEquity"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_9fdee22d-8c83-4f57-909a-ba031993d3e3" xlink:to="loc_us-gaap_StockholdersEquity_9d349988-9f65-4c72-a06e-1d7ca09100ab" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_f501b588-1629-4a02-b059-ed58e58e6349" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AssetsCurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryNet_cbedce48-4bc9-4ace-9631-5cc2c9378377" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InventoryNet"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_f501b588-1629-4a02-b059-ed58e58e6349" xlink:to="loc_us-gaap_InventoryNet_cbedce48-4bc9-4ace-9631-5cc2c9378377" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesReceivable_cfe73d26-ff21-456e-a02a-791584b0b786" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxesReceivable"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_f501b588-1629-4a02-b059-ed58e58e6349" xlink:to="loc_us-gaap_IncomeTaxesReceivable_cfe73d26-ff21-456e-a02a-791584b0b786" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashCurrent_f4520ff9-de69-4967-94c2-9a25bbd6cb11" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RestrictedCashCurrent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_f501b588-1629-4a02-b059-ed58e58e6349" xlink:to="loc_us-gaap_RestrictedCashCurrent_f4520ff9-de69-4967-94c2-9a25bbd6cb11" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_dc56bd44-aef8-4e03-82f6-b54a1be13666" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_f501b588-1629-4a02-b059-ed58e58e6349" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_dc56bd44-aef8-4e03-82f6-b54a1be13666" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_671b14c9-0d1c-4647-a879-8cf303e0955e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_f501b588-1629-4a02-b059-ed58e58e6349" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_671b14c9-0d1c-4647-a879-8cf303e0955e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_4e8cf9a6-73b3-4a76-abb5-e7be51d44222" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_f501b588-1629-4a02-b059-ed58e58e6349" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_4e8cf9a6-73b3-4a76-abb5-e7be51d44222" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_3e26475c-2780-4b50-b07a-3ccfa895cd47" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Liabilities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_21bdeb56-afb1-4e6d-8d64-255873f87950" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_3e26475c-2780-4b50-b07a-3ccfa895cd47" xlink:to="loc_us-gaap_LiabilitiesCurrent_21bdeb56-afb1-4e6d-8d64-255873f87950" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_42a2ec3f-eed7-420b-9d9d-93572d69aaa1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_3e26475c-2780-4b50-b07a-3ccfa895cd47" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_42a2ec3f-eed7-420b-9d9d-93572d69aaa1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_25e8e18a-2611-41d4-a219-139e85a52552" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_3e26475c-2780-4b50-b07a-3ccfa895cd47" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_25e8e18a-2611-41d4-a219-139e85a52552" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityNoncurrent_9af13076-02b2-43d6-b799-918ad4c06285" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ContractWithCustomerLiabilityNoncurrent"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_3e26475c-2780-4b50-b07a-3ccfa895cd47" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityNoncurrent_9af13076-02b2-43d6-b799-918ad4c06285" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_5de4ff40-a2a3-4d2d-816a-12b82f479de1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrent"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_3e26475c-2780-4b50-b07a-3ccfa895cd47" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_5de4ff40-a2a3-4d2d-816a-12b82f479de1" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/CONSOLIDATEDSTATEMENTSOFOPERATIONS" xlink:type="simple" xlink:href="psix-20211231.xsd#CONSOLIDATEDSTATEMENTSOFOPERATIONS"/>
  <link:calculationLink xlink:role="http://powersint.com/role/CONSOLIDATEDSTATEMENTSOFOPERATIONS" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_129840bb-6abd-40fd-bf9a-9cf9719e7867" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_96acbcf2-9e4e-438f-abd7-f2c9b3773f7f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_129840bb-6abd-40fd-bf9a-9cf9719e7867" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_96acbcf2-9e4e-438f-abd7-f2c9b3773f7f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_b51b74ad-70e0-4abe-b075-41c029bc2f2a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestExpense"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_129840bb-6abd-40fd-bf9a-9cf9719e7867" xlink:to="loc_us-gaap_InterestExpense_b51b74ad-70e0-4abe-b075-41c029bc2f2a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_95807d50-3d4c-472e-8e93-9bccb4025262" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_129840bb-6abd-40fd-bf9a-9cf9719e7867" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_95807d50-3d4c-472e-8e93-9bccb4025262" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpenses_8b51aa61-142e-46b6-8de5-47a200a34aea" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingExpenses"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_4f4290dc-5323-4a7f-b003-8038fbf304d9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingExpenses_8b51aa61-142e-46b6-8de5-47a200a34aea" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_4f4290dc-5323-4a7f-b003-8038fbf304d9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingAndMarketingExpense_6c2a4d99-4178-48d4-855a-92f7d5e6bea3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SellingAndMarketingExpense"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingExpenses_8b51aa61-142e-46b6-8de5-47a200a34aea" xlink:to="loc_us-gaap_SellingAndMarketingExpense_6c2a4d99-4178-48d4-855a-92f7d5e6bea3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_ce007d77-ad7c-42fd-bab6-0f08e94c5aa2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingExpenses_8b51aa61-142e-46b6-8de5-47a200a34aea" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_ce007d77-ad7c-42fd-bab6-0f08e94c5aa2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_7a5f90de-6ae5-49a1-af6e-ed344f78dd2f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_7277f108-f725-44a8-8dc7-dc2f0777fc62" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_7a5f90de-6ae5-49a1-af6e-ed344f78dd2f" xlink:to="loc_us-gaap_OperatingIncomeLoss_7277f108-f725-44a8-8dc7-dc2f0777fc62" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_06e8cc22-906c-4c28-a0db-8282850ce97f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_7a5f90de-6ae5-49a1-af6e-ed344f78dd2f" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_06e8cc22-906c-4c28-a0db-8282850ce97f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_c5663f7f-ff3a-4628-83c9-3c4282b2f34e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossProfit_7c3447c2-ef4b-450c-84bf-7f6cdc6d7fb5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GrossProfit"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingIncomeLoss_c5663f7f-ff3a-4628-83c9-3c4282b2f34e" xlink:to="loc_us-gaap_GrossProfit_7c3447c2-ef4b-450c-84bf-7f6cdc6d7fb5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpenses_74228c57-b4e2-4360-aa1d-9bcc5e6a0106" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingExpenses"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingIncomeLoss_c5663f7f-ff3a-4628-83c9-3c4282b2f34e" xlink:to="loc_us-gaap_OperatingExpenses_74228c57-b4e2-4360-aa1d-9bcc5e6a0106" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossProfit_bd9ed99c-85cf-445c-810c-08c55f25b946" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GrossProfit"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_fffb028c-4bf1-4256-8aaa-6e4ff1ce8b3b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_GrossProfit_bd9ed99c-85cf-445c-810c-08c55f25b946" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_fffb028c-4bf1-4256-8aaa-6e4ff1ce8b3b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_6291b3fe-80f4-44bf-917d-82b267a313ec" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_GrossProfit_bd9ed99c-85cf-445c-810c-08c55f25b946" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_6291b3fe-80f4-44bf-917d-82b267a313ec" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_b2b8bf9c-1d19-49e0-90af-e816be4ec78e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_983f7247-27c5-4ca1-8fae-f495c3ed9a1a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_b2b8bf9c-1d19-49e0-90af-e816be4ec78e" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_983f7247-27c5-4ca1-8fae-f495c3ed9a1a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_e2efc2c6-d805-4b21-995c-2d51da354f53" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_b2b8bf9c-1d19-49e0-90af-e816be4ec78e" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_e2efc2c6-d805-4b21-995c-2d51da354f53" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/CONSOLIDATEDSTATEMENTSOFCASHFLOWS" xlink:type="simple" xlink:href="psix-20211231.xsd#CONSOLIDATEDSTATEMENTSOFCASHFLOWS"/>
  <link:calculationLink xlink:role="http://powersint.com/role/CONSOLIDATEDSTATEMENTSOFCASHFLOWS" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_4ca99e07-9e93-4118-ae25-1844ef2ae237" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_6824cf59-85f5-4555-9671-8b2eff0c7418" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_4ca99e07-9e93-4118-ae25-1844ef2ae237" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_6824cf59-85f5-4555-9671-8b2eff0c7418" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashCurrent_158b800f-b582-49f6-bc6a-22cf15653fa2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RestrictedCashCurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_4ca99e07-9e93-4118-ae25-1844ef2ae237" xlink:to="loc_us-gaap_RestrictedCashCurrent_158b800f-b582-49f6-bc6a-22cf15653fa2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_818ae74c-f683-4d1b-a433-8c85664e6946" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_766f020e-85d1-466d-bbac-1d63a6a53983" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_818ae74c-f683-4d1b-a433-8c85664e6946" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_766f020e-85d1-466d-bbac-1d63a6a53983" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_46d799bb-fb39-4509-a3c3-b0948e18e671" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_818ae74c-f683-4d1b-a433-8c85664e6946" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_46d799bb-fb39-4509-a3c3-b0948e18e671" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_02bf0e90-e0a4-4d53-8dd7-eb9650f68c6a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_818ae74c-f683-4d1b-a433-8c85664e6946" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_02bf0e90-e0a4-4d53-8dd7-eb9650f68c6a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_31d54c72-9624-4c7d-9028-bacc2da2ec4e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfShortTermDebt_bd0862e2-62c6-4385-a344-65767145659b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RepaymentsOfShortTermDebt"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_31d54c72-9624-4c7d-9028-bacc2da2ec4e" xlink:to="loc_us-gaap_RepaymentsOfShortTermDebt_bd0862e2-62c6-4385-a344-65767145659b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromLongTermLinesOfCredit_25fd305a-1540-4d93-853d-39065d17a39e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromLongTermLinesOfCredit"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_31d54c72-9624-4c7d-9028-bacc2da2ec4e" xlink:to="loc_us-gaap_ProceedsFromLongTermLinesOfCredit_25fd305a-1540-4d93-853d-39065d17a39e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromShortTermDebt_9311f9e8-a739-4611-97fd-117cc649665f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromShortTermDebt"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_31d54c72-9624-4c7d-9028-bacc2da2ec4e" xlink:to="loc_us-gaap_ProceedsFromShortTermDebt_9311f9e8-a739-4611-97fd-117cc649665f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDebtIssuanceCosts_cffb3802-aef8-4938-b02a-e6162a394bb7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsOfDebtIssuanceCosts"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_31d54c72-9624-4c7d-9028-bacc2da2ec4e" xlink:to="loc_us-gaap_PaymentsOfDebtIssuanceCosts_cffb3802-aef8-4938-b02a-e6162a394bb7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLongTermLinesOfCredit_a45051c6-becf-4113-9f71-a4fbc388092d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RepaymentsOfLongTermLinesOfCredit"/>
    <link:calculationArc order="5" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_31d54c72-9624-4c7d-9028-bacc2da2ec4e" xlink:to="loc_us-gaap_RepaymentsOfLongTermLinesOfCredit_a45051c6-becf-4113-9f71-a4fbc388092d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_e78a7923-3502-430c-8c96-3b556daf5484" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromPaymentsForOtherFinancingActivities"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_31d54c72-9624-4c7d-9028-bacc2da2ec4e" xlink:to="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_e78a7923-3502-430c-8c96-3b556daf5484" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfDebtAndCapitalLeaseObligations_8425b50d-1538-4668-adef-5899aa0bfaff" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RepaymentsOfDebtAndCapitalLeaseObligations"/>
    <link:calculationArc order="7" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_31d54c72-9624-4c7d-9028-bacc2da2ec4e" xlink:to="loc_us-gaap_RepaymentsOfDebtAndCapitalLeaseObligations_8425b50d-1538-4668-adef-5899aa0bfaff" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_a694b199-3548-4f95-9ede-df5bd243dbc5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_a643488e-3169-40a3-b29f-84ea2cc76612" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_a694b199-3548-4f95-9ede-df5bd243dbc5" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_a643488e-3169-40a3-b29f-84ea2cc76612" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_3d8309e2-e2b1-41df-a855-5c02eea96efc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_a694b199-3548-4f95-9ede-df5bd243dbc5" xlink:to="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_3d8309e2-e2b1-41df-a855-5c02eea96efc" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_8634c938-9076-4cd9-950b-010c2ae98c56" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Depreciation"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_a694b199-3548-4f95-9ede-df5bd243dbc5" xlink:to="loc_us-gaap_Depreciation_8634c938-9076-4cd9-950b-010c2ae98c56" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccruedLiabilities_5ec3d201-186d-466e-9507-60adcc93a121" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInAccruedLiabilities"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_a694b199-3548-4f95-9ede-df5bd243dbc5" xlink:to="loc_us-gaap_IncreaseDecreaseInAccruedLiabilities_5ec3d201-186d-466e-9507-60adcc93a121" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentLiabilities_987b1f26-e55b-4ec1-a9a6-1ca974717f91" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInOtherNoncurrentLiabilities"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_a694b199-3548-4f95-9ede-df5bd243dbc5" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentLiabilities_987b1f26-e55b-4ec1-a9a6-1ca974717f91" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaidInKindInterest_1684d460-955a-496d-8f08-54ca3d53890c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaidInKindInterest"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_a694b199-3548-4f95-9ede-df5bd243dbc5" xlink:to="loc_us-gaap_PaidInKindInterest_1684d460-955a-496d-8f08-54ca3d53890c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayableTrade_3e1f59fa-a93f-497c-8b5c-1eed808f9720" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsPayableTrade"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_a694b199-3548-4f95-9ede-df5bd243dbc5" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayableTrade_3e1f59fa-a93f-497c-8b5c-1eed808f9720" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_122d5972-16ba-4488-9bb2-064130fad815" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_a694b199-3548-4f95-9ede-df5bd243dbc5" xlink:to="loc_us-gaap_NetIncomeLoss_122d5972-16ba-4488-9bb2-064130fad815" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherOperatingActivitiesCashFlowStatement_25ea1061-7c83-43c7-9611-03e84c83601a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherOperatingActivitiesCashFlowStatement"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_a694b199-3548-4f95-9ede-df5bd243dbc5" xlink:to="loc_us-gaap_OtherOperatingActivitiesCashFlowStatement_25ea1061-7c83-43c7-9611-03e84c83601a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_psix_AmortizationOfIntangibleAssetsCostAndOperatingExpense_54c640d5-5168-4dcf-9204-9e2129bf2956" xlink:href="psix-20211231.xsd#psix_AmortizationOfIntangibleAssetsCostAndOperatingExpense"/>
    <link:calculationArc order="10" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_a694b199-3548-4f95-9ede-df5bd243dbc5" xlink:to="loc_psix_AmortizationOfIntangibleAssetsCostAndOperatingExpense_54c640d5-5168-4dcf-9204-9e2129bf2956" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInInventories_7d0d9998-310a-4893-82d0-d16de90c6cb7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInInventories"/>
    <link:calculationArc order="11" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_a694b199-3548-4f95-9ede-df5bd243dbc5" xlink:to="loc_us-gaap_IncreaseDecreaseInInventories_7d0d9998-310a-4893-82d0-d16de90c6cb7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_a716af95-c3c5-4a69-953d-df82af9625a2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable"/>
    <link:calculationArc order="12" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_a694b199-3548-4f95-9ede-df5bd243dbc5" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_a716af95-c3c5-4a69-953d-df82af9625a2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_3fc8fd22-b18c-4529-bc82-2da23d01209e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensation"/>
    <link:calculationArc order="13" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_a694b199-3548-4f95-9ede-df5bd243dbc5" xlink:to="loc_us-gaap_ShareBasedCompensation_3fc8fd22-b18c-4529-bc82-2da23d01209e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxesAndTaxCredits_00507e71-240d-402a-abf2-42dc0f4e6e40" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredIncomeTaxesAndTaxCredits"/>
    <link:calculationArc order="14" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_a694b199-3548-4f95-9ede-df5bd243dbc5" xlink:to="loc_us-gaap_DeferredIncomeTaxesAndTaxCredits_00507e71-240d-402a-abf2-42dc0f4e6e40" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_62272c61-85b4-4175-83c0-65bf5f8d8d6f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital_2f380220-3a92-4933-ab52-76eecfe2ecbd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_62272c61-85b4-4175-83c0-65bf5f8d8d6f" xlink:to="loc_us-gaap_ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital_2f380220-3a92-4933-ab52-76eecfe2ecbd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForCapitalImprovements_c27ac9da-3356-4800-83da-873f8ffdc7f9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsForCapitalImprovements"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_62272c61-85b4-4175-83c0-65bf5f8d8d6f" xlink:to="loc_us-gaap_PaymentsForCapitalImprovements_c27ac9da-3356-4800-83da-873f8ffdc7f9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromLifeInsurancePolicies_bc518126-9946-4932-a00f-2c8a0ae3f036" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromLifeInsurancePolicies"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_62272c61-85b4-4175-83c0-65bf5f8d8d6f" xlink:to="loc_us-gaap_ProceedsFromLifeInsurancePolicies_bc518126-9946-4932-a00f-2c8a0ae3f036" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForProceedsFromOtherInvestingActivities_aa6809c2-5d3f-4823-8111-3eb2ef93be1b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsForProceedsFromOtherInvestingActivities"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_62272c61-85b4-4175-83c0-65bf5f8d8d6f" xlink:to="loc_us-gaap_PaymentsForProceedsFromOtherInvestingActivities_aa6809c2-5d3f-4823-8111-3eb2ef93be1b" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/SummaryofSignificantAccountingPoliciesandOtherInformationScheduleofInventoryCurrentDetails" xlink:type="simple" xlink:href="psix-20211231.xsd#SummaryofSignificantAccountingPoliciesandOtherInformationScheduleofInventoryCurrentDetails"/>
  <link:calculationLink xlink:role="http://powersint.com/role/SummaryofSignificantAccountingPoliciesandOtherInformationScheduleofInventoryCurrentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryNet_c72fafc8-ff1b-4326-ac63-6c8de3da9397" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InventoryNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryGross_689847f9-7cc4-4a49-a664-19ccb5c5a3d9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InventoryGross"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InventoryNet_c72fafc8-ff1b-4326-ac63-6c8de3da9397" xlink:to="loc_us-gaap_InventoryGross_689847f9-7cc4-4a49-a664-19ccb5c5a3d9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryValuationReserves_b351a08f-809c-43d7-9c69-39fa7a8c5897" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InventoryValuationReserves"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InventoryNet_c72fafc8-ff1b-4326-ac63-6c8de3da9397" xlink:to="loc_us-gaap_InventoryValuationReserves_b351a08f-809c-43d7-9c69-39fa7a8c5897" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryGross_ae8a8ad8-2992-4c53-b3eb-5016096f3653" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InventoryGross"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryRawMaterials_b6513cd8-ef4e-499f-9883-b2d1cd0bb16d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InventoryRawMaterials"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InventoryGross_ae8a8ad8-2992-4c53-b3eb-5016096f3653" xlink:to="loc_us-gaap_InventoryRawMaterials_b6513cd8-ef4e-499f-9883-b2d1cd0bb16d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryWorkInProcess_2f2bd39e-63e5-4f8f-a389-4a91bd75e7d3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InventoryWorkInProcess"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InventoryGross_ae8a8ad8-2992-4c53-b3eb-5016096f3653" xlink:to="loc_us-gaap_InventoryWorkInProcess_2f2bd39e-63e5-4f8f-a389-4a91bd75e7d3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryFinishedGoods_6472a1fb-392f-4fbb-a16c-997fa197c120" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InventoryFinishedGoods"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InventoryGross_ae8a8ad8-2992-4c53-b3eb-5016096f3653" xlink:to="loc_us-gaap_InventoryFinishedGoods_6472a1fb-392f-4fbb-a16c-997fa197c120" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/SummaryofSignificantAccountingPoliciesandOtherInformationScheduleofOtherAccruedLiabilitiesDetails" xlink:type="simple" xlink:href="psix-20211231.xsd#SummaryofSignificantAccountingPoliciesandOtherInformationScheduleofOtherAccruedLiabilitiesDetails"/>
  <link:calculationLink xlink:role="http://powersint.com/role/SummaryofSignificantAccountingPoliciesandOtherInformationScheduleofOtherAccruedLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilities_661d7b93-0b05-484e-a9ec-209cd4699630" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccruedLiabilitiesAndOtherLiabilities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StandardProductWarrantyAccrualCurrent_d3ca0483-f5be-48fe-a0e8-3fbd577b6837" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StandardProductWarrantyAccrualCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilities_661d7b93-0b05-484e-a9ec-209cd4699630" xlink:to="loc_us-gaap_StandardProductWarrantyAccrualCurrent_d3ca0483-f5be-48fe-a0e8-3fbd577b6837" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationReserve_0e7321cd-3812-4d60-a0ca-6d5ec552886a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LitigationReserve"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilities_661d7b93-0b05-484e-a9ec-209cd4699630" xlink:to="loc_us-gaap_LitigationReserve_0e7321cd-3812-4d60-a0ca-6d5ec552886a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_6e325869-73b4-44fa-b831-4b237e8459ee" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilities_661d7b93-0b05-484e-a9ec-209cd4699630" xlink:to="loc_us-gaap_ContractWithCustomerLiability_6e325869-73b4-44fa-b831-4b237e8459ee" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedEmployeeBenefitsCurrentAndNoncurrent_4a52d3d8-552d-4694-9a26-ac0b26e31879" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccruedEmployeeBenefitsCurrentAndNoncurrent"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilities_661d7b93-0b05-484e-a9ec-209cd4699630" xlink:to="loc_us-gaap_AccruedEmployeeBenefitsCurrentAndNoncurrent_4a52d3d8-552d-4694-9a26-ac0b26e31879" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_8e26ad38-5233-46ac-9045-9f18ff2ce0ff" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseLiabilityCurrent"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilities_661d7b93-0b05-484e-a9ec-209cd4699630" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_8e26ad38-5233-46ac-9045-9f18ff2ce0ff" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPayableCurrent_dfd64dd5-a6ba-4860-9f2e-75b67df550b4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestPayableCurrent"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilities_661d7b93-0b05-484e-a9ec-209cd4699630" xlink:to="loc_us-gaap_InterestPayableCurrent_dfd64dd5-a6ba-4860-9f2e-75b67df550b4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherSundryLiabilitiesCurrent_77f25bc2-3b63-489d-b786-4c7a4c408a83" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherSundryLiabilitiesCurrent"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilities_661d7b93-0b05-484e-a9ec-209cd4699630" xlink:to="loc_us-gaap_OtherSundryLiabilitiesCurrent_77f25bc2-3b63-489d-b786-4c7a4c408a83" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/SummaryofSignificantAccountingPoliciesandOtherInformationScheduleofAccruedProductWarrantyDetails" xlink:type="simple" xlink:href="psix-20211231.xsd#SummaryofSignificantAccountingPoliciesandOtherInformationScheduleofAccruedProductWarrantyDetails"/>
  <link:calculationLink xlink:role="http://powersint.com/role/SummaryofSignificantAccountingPoliciesandOtherInformationScheduleofAccruedProductWarrantyDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StandardProductWarrantyAccrual_d7cfc299-266a-4b20-a4f2-f7e730560577" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StandardProductWarrantyAccrual"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StandardProductWarrantyAccrualNoncurrent_90490ec0-c7af-424e-b26a-365768dbca8e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StandardProductWarrantyAccrualNoncurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StandardProductWarrantyAccrual_d7cfc299-266a-4b20-a4f2-f7e730560577" xlink:to="loc_us-gaap_StandardProductWarrantyAccrualNoncurrent_90490ec0-c7af-424e-b26a-365768dbca8e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StandardProductWarrantyAccrualCurrent_3726e8c1-b8fd-442b-ac68-63c3e6db80bb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StandardProductWarrantyAccrualCurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StandardProductWarrantyAccrual_d7cfc299-266a-4b20-a4f2-f7e730560577" xlink:to="loc_us-gaap_StandardProductWarrantyAccrualCurrent_3726e8c1-b8fd-442b-ac68-63c3e6db80bb" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/RevenueScheduleofContractBalancesDetails" xlink:type="simple" xlink:href="psix-20211231.xsd#RevenueScheduleofContractBalancesDetails"/>
  <link:calculationLink xlink:role="http://powersint.com/role/RevenueScheduleofContractBalancesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_psix_ContractWithCustomerAssetLiability_2856d1c1-456f-448c-ab83-97f00892c971" xlink:href="psix-20211231.xsd#psix_ContractWithCustomerAssetLiability"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerAssetGrossCurrent_030e267b-2b00-4472-90f6-c46515536530" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ContractWithCustomerAssetGrossCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_psix_ContractWithCustomerAssetLiability_2856d1c1-456f-448c-ab83-97f00892c971" xlink:to="loc_us-gaap_ContractWithCustomerAssetGrossCurrent_030e267b-2b00-4472-90f6-c46515536530" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityCurrent_1d2db826-b3f4-46e4-abc4-b75b9ca18fb9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ContractWithCustomerLiabilityCurrent"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_psix_ContractWithCustomerAssetLiability_2856d1c1-456f-448c-ab83-97f00892c971" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityCurrent_1d2db826-b3f4-46e4-abc4-b75b9ca18fb9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityNoncurrent_edc6c7c8-7bff-459b-9008-3250e755b0c6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ContractWithCustomerLiabilityNoncurrent"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_psix_ContractWithCustomerAssetLiability_2856d1c1-456f-448c-ab83-97f00892c971" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityNoncurrent_edc6c7c8-7bff-459b-9008-3250e755b0c6" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/PropertyPlantandEquipmentPropertyPlantandEquipmentDetails" xlink:type="simple" xlink:href="psix-20211231.xsd#PropertyPlantandEquipmentPropertyPlantandEquipmentDetails"/>
  <link:calculationLink xlink:role="http://powersint.com/role/PropertyPlantandEquipmentPropertyPlantandEquipmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_d30d3f78-989b-4dc6-aef5-1f6e4c5cd94c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_a01c30d5-c884-48b7-814d-961f804f00ce" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_d30d3f78-989b-4dc6-aef5-1f6e4c5cd94c" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_a01c30d5-c884-48b7-814d-961f804f00ce" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_d6019517-11e9-40d7-8364-bcde53681a5a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_d30d3f78-989b-4dc6-aef5-1f6e4c5cd94c" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_d6019517-11e9-40d7-8364-bcde53681a5a" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/GoodwillandOtherIntangiblesScheduleofFiniteLivedIntangibleAssetsDetails" xlink:type="simple" xlink:href="psix-20211231.xsd#GoodwillandOtherIntangiblesScheduleofFiniteLivedIntangibleAssetsDetails"/>
  <link:calculationLink xlink:role="http://powersint.com/role/GoodwillandOtherIntangiblesScheduleofFiniteLivedIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_7bfbf093-45d3-464a-bbf6-d20ce122ac43" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_e1c6d17a-f6a2-4249-86c3-7e99e2fa5c38" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet_7bfbf093-45d3-464a-bbf6-d20ce122ac43" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_e1c6d17a-f6a2-4249-86c3-7e99e2fa5c38" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_8768b13a-9aba-49f1-a39e-da630c3aa7e6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet_7bfbf093-45d3-464a-bbf6-d20ce122ac43" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_8768b13a-9aba-49f1-a39e-da630c3aa7e6" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/GoodwillandOtherIntangiblesScheduleofFutureAmortizationExpenseDetails" xlink:type="simple" xlink:href="psix-20211231.xsd#GoodwillandOtherIntangiblesScheduleofFutureAmortizationExpenseDetails"/>
  <link:calculationLink xlink:role="http://powersint.com/role/GoodwillandOtherIntangiblesScheduleofFutureAmortizationExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_ae5cd37d-ac4c-4d4d-8353-c3f3cf72a30f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_1ac90104-98b3-4088-bf17-7194a18b4fb0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet_ae5cd37d-ac4c-4d4d-8353-c3f3cf72a30f" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_1ac90104-98b3-4088-bf17-7194a18b4fb0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_b35dad1d-fe8c-49e8-a868-086ddb3761e4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet_ae5cd37d-ac4c-4d4d-8353-c3f3cf72a30f" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_b35dad1d-fe8c-49e8-a868-086ddb3761e4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_008a3d13-23e7-4dc7-a1ef-329ebaa2842b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet_ae5cd37d-ac4c-4d4d-8353-c3f3cf72a30f" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_008a3d13-23e7-4dc7-a1ef-329ebaa2842b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_51f62091-5874-4b51-b8a9-2bbacc301f04" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet_ae5cd37d-ac4c-4d4d-8353-c3f3cf72a30f" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_51f62091-5874-4b51-b8a9-2bbacc301f04" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_be33ad25-399f-41c8-9219-3155aba81a11" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet_ae5cd37d-ac4c-4d4d-8353-c3f3cf72a30f" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_be33ad25-399f-41c8-9219-3155aba81a11" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive_6ab55a91-f57d-44cc-b8ac-53cc542d5f1b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet_ae5cd37d-ac4c-4d4d-8353-c3f3cf72a30f" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive_6ab55a91-f57d-44cc-b8ac-53cc542d5f1b" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/DebtScheduleofDebtDetails" xlink:type="simple" xlink:href="psix-20211231.xsd#DebtScheduleofDebtDetails"/>
  <link:calculationLink xlink:role="http://powersint.com/role/DebtScheduleofDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_a38d4928-9a3b-42a7-84a9-ffdbcb1d4bb8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligations"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent_3faa26ab-deb1-4820-b74e-869d966d3585" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_a38d4928-9a3b-42a7-84a9-ffdbcb1d4bb8" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent_3faa26ab-deb1-4820-b74e-869d966d3585" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_3eb14824-8732-427c-a86d-2c5cbe7e897b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebt"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_a38d4928-9a3b-42a7-84a9-ffdbcb1d4bb8" xlink:to="loc_us-gaap_LongTermDebt_3eb14824-8732-427c-a86d-2c5cbe7e897b" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/DebtScheduleofDebtDetails_1" xlink:type="simple" xlink:href="psix-20211231.xsd#DebtScheduleofDebtDetails_1"/>
  <link:calculationLink xlink:role="http://powersint.com/role/DebtScheduleofDebtDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_bb353062-4a5e-4646-82c8-5cc48a01887e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligations"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubordinatedLongTermDebt_7438a9d6-52d7-46b0-a72d-9db8470be8f8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubordinatedLongTermDebt"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_bb353062-4a5e-4646-82c8-5cc48a01887e" xlink:to="loc_us-gaap_SubordinatedLongTermDebt_7438a9d6-52d7-46b0-a72d-9db8470be8f8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_psix_FinanceLeaseLiabilityAndOtherLongTermDebt_50a8003a-dfdb-48d4-b363-90978dcb324e" xlink:href="psix-20211231.xsd#psix_FinanceLeaseLiabilityAndOtherLongTermDebt"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_bb353062-4a5e-4646-82c8-5cc48a01887e" xlink:to="loc_psix_FinanceLeaseLiabilityAndOtherLongTermDebt_50a8003a-dfdb-48d4-b363-90978dcb324e" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/DebtScheduleofMaturitiesofLongTermDebtDetails" xlink:type="simple" xlink:href="psix-20211231.xsd#DebtScheduleofMaturitiesofLongTermDebtDetails"/>
  <link:calculationLink xlink:role="http://powersint.com/role/DebtScheduleofMaturitiesofLongTermDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_e0e57c9d-6a34-495f-aed9-51ed8113f609" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths_66fb9c35-a18a-4aa0-814b-86209afb5798" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DebtInstrumentCarryingAmount_e0e57c9d-6a34-495f-aed9-51ed8113f609" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths_66fb9c35-a18a-4aa0-814b-86209afb5798" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo_f08eea1e-72a3-4407-a87d-72f5f2f648a4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DebtInstrumentCarryingAmount_e0e57c9d-6a34-495f-aed9-51ed8113f609" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo_f08eea1e-72a3-4407-a87d-72f5f2f648a4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree_35e2d4bb-8dc4-4485-a74e-f784c3a9a64a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DebtInstrumentCarryingAmount_e0e57c9d-6a34-495f-aed9-51ed8113f609" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree_35e2d4bb-8dc4-4485-a74e-f784c3a9a64a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour_47efa147-974b-419f-8574-8aaffca593ef" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DebtInstrumentCarryingAmount_e0e57c9d-6a34-495f-aed9-51ed8113f609" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour_47efa147-974b-419f-8574-8aaffca593ef" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive_4d9d6e88-c6e7-495b-b7a9-1c1838842060" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DebtInstrumentCarryingAmount_e0e57c9d-6a34-495f-aed9-51ed8113f609" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive_4d9d6e88-c6e7-495b-b7a9-1c1838842060" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/LeasesComponentsofLeaseExpenseDetails" xlink:type="simple" xlink:href="psix-20211231.xsd#LeasesComponentsofLeaseExpenseDetails"/>
  <link:calculationLink xlink:role="http://powersint.com/role/LeasesComponentsofLeaseExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseCost_2036e3b8-b10c-4803-b0f6-8d8b8283fff2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LeaseCost"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseCost_03ec3c2c-fe74-4c69-9799-72e904dee8c0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseCost"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LeaseCost_2036e3b8-b10c-4803-b0f6-8d8b8283fff2" xlink:to="loc_us-gaap_OperatingLeaseCost_03ec3c2c-fe74-4c69-9799-72e904dee8c0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAssetAmortization_6bc04cc8-1bbb-43c4-a91b-c9f41cdd0681" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinanceLeaseRightOfUseAssetAmortization"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LeaseCost_2036e3b8-b10c-4803-b0f6-8d8b8283fff2" xlink:to="loc_us-gaap_FinanceLeaseRightOfUseAssetAmortization_6bc04cc8-1bbb-43c4-a91b-c9f41cdd0681" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseInterestExpense_8dc816dc-6f8d-4b93-80b0-a08448b0dff0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinanceLeaseInterestExpense"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LeaseCost_2036e3b8-b10c-4803-b0f6-8d8b8283fff2" xlink:to="loc_us-gaap_FinanceLeaseInterestExpense_8dc816dc-6f8d-4b93-80b0-a08448b0dff0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermLeaseCost_a0397bcc-5aec-46e9-9a45-57bf8f07feab" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShortTermLeaseCost"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LeaseCost_2036e3b8-b10c-4803-b0f6-8d8b8283fff2" xlink:to="loc_us-gaap_ShortTermLeaseCost_a0397bcc-5aec-46e9-9a45-57bf8f07feab" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableLeaseCost_20ca4cb0-7ea3-4cdf-a438-822313d010ca" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VariableLeaseCost"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LeaseCost_2036e3b8-b10c-4803-b0f6-8d8b8283fff2" xlink:to="loc_us-gaap_VariableLeaseCost_20ca4cb0-7ea3-4cdf-a438-822313d010ca" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/LeasesSupplementalBalanceSheetInformationDetails" xlink:type="simple" xlink:href="psix-20211231.xsd#LeasesSupplementalBalanceSheetInformationDetails"/>
  <link:calculationLink xlink:role="http://powersint.com/role/LeasesSupplementalBalanceSheetInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiability_7dc0320a-b7d0-4d1b-bfbc-8f10b028cd60" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinanceLeaseLiability"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityCurrent_a2e13747-ea1c-40ef-bcd3-2a932ecc3cdc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinanceLeaseLiabilityCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiability_7dc0320a-b7d0-4d1b-bfbc-8f10b028cd60" xlink:to="loc_us-gaap_FinanceLeaseLiabilityCurrent_a2e13747-ea1c-40ef-bcd3-2a932ecc3cdc" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityNoncurrent_47ee9d27-27e1-48c3-8642-98a400f71e9c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinanceLeaseLiabilityNoncurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiability_7dc0320a-b7d0-4d1b-bfbc-8f10b028cd60" xlink:to="loc_us-gaap_FinanceLeaseLiabilityNoncurrent_47ee9d27-27e1-48c3-8642-98a400f71e9c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_6bc84878-79ba-4e3c-9621-84339ec87cea" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseLiability"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_a81d601b-25b6-4f34-8bab-d9aa3b1785b7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseLiabilityCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingLeaseLiability_6bc84878-79ba-4e3c-9621-84339ec87cea" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_a81d601b-25b6-4f34-8bab-d9aa3b1785b7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_cddfddc3-09b9-472a-824c-2af475a28988" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingLeaseLiability_6bc84878-79ba-4e3c-9621-84339ec87cea" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_cddfddc3-09b9-472a-824c-2af475a28988" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/LeasesMaturityAnalysisofLeaseLiabilitiesDetails" xlink:type="simple" xlink:href="psix-20211231.xsd#LeasesMaturityAnalysisofLeaseLiabilitiesDetails"/>
  <link:calculationLink xlink:role="http://powersint.com/role/LeasesMaturityAnalysisofLeaseLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_086a9dc5-7d89-4bee-aefa-6b683dc8578a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount_57ed1441-1a15-415b-85c9-adef584d662f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_086a9dc5-7d89-4bee-aefa-6b683dc8578a" xlink:to="loc_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount_57ed1441-1a15-415b-85c9-adef584d662f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiability_8042b971-d6d8-4b58-8257-4a2f08049cc2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinanceLeaseLiability"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_086a9dc5-7d89-4bee-aefa-6b683dc8578a" xlink:to="loc_us-gaap_FinanceLeaseLiability_8042b971-d6d8-4b58-8257-4a2f08049cc2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_9ead18ce-8e13-44f2-b9d9-f3d53d63fd05" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_4fb2f776-22de-4e30-bcef-1acfaeecf01e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_9ead18ce-8e13-44f2-b9d9-f3d53d63fd05" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_4fb2f776-22de-4e30-bcef-1acfaeecf01e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_9cf80c32-7958-41b2-a203-8c4f5db113d6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_9ead18ce-8e13-44f2-b9d9-f3d53d63fd05" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_9cf80c32-7958-41b2-a203-8c4f5db113d6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_c7a6c249-2655-4052-9c1a-3638f978a1ad" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_9ead18ce-8e13-44f2-b9d9-f3d53d63fd05" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_c7a6c249-2655-4052-9c1a-3638f978a1ad" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_d4940e16-5124-4433-8215-8d32360b0099" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_9ead18ce-8e13-44f2-b9d9-f3d53d63fd05" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_d4940e16-5124-4433-8215-8d32360b0099" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_daf49273-5ea1-41e2-a59d-1a792209c387" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_9ead18ce-8e13-44f2-b9d9-f3d53d63fd05" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_daf49273-5ea1-41e2-a59d-1a792209c387" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_416da050-1a9a-4994-9016-3ef5dd808c4e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_9ead18ce-8e13-44f2-b9d9-f3d53d63fd05" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_416da050-1a9a-4994-9016-3ef5dd808c4e" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/LeasesMaturityAnalysisofLeaseLiabilitiesDetails_1" xlink:type="simple" xlink:href="psix-20211231.xsd#LeasesMaturityAnalysisofLeaseLiabilitiesDetails_1"/>
  <link:calculationLink xlink:role="http://powersint.com/role/LeasesMaturityAnalysisofLeaseLiabilitiesDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_8a018d8b-ef52-42ee-9a1f-476baf11aab7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths_819d8bd3-e518-4f74-a34b-ccdc69db017c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_8a018d8b-ef52-42ee-9a1f-476baf11aab7" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths_819d8bd3-e518-4f74-a34b-ccdc69db017c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo_0f750b6b-4b42-4205-a5b5-75356350e5da" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_8a018d8b-ef52-42ee-9a1f-476baf11aab7" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo_0f750b6b-4b42-4205-a5b5-75356350e5da" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree_cd304ea9-c22d-499d-acb6-bc2090117878" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_8a018d8b-ef52-42ee-9a1f-476baf11aab7" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree_cd304ea9-c22d-499d-acb6-bc2090117878" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour_93f9a554-1a09-4290-a221-3f925e8ee3ee" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_8a018d8b-ef52-42ee-9a1f-476baf11aab7" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour_93f9a554-1a09-4290-a221-3f925e8ee3ee" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive_22a24631-518d-40c5-8f49-9ce58e5eab89" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_8a018d8b-ef52-42ee-9a1f-476baf11aab7" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive_22a24631-518d-40c5-8f49-9ce58e5eab89" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive_23df3437-4e2c-46ef-b48a-bdfebea800c2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_8a018d8b-ef52-42ee-9a1f-476baf11aab7" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive_23df3437-4e2c-46ef-b48a-bdfebea800c2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_8c93f82c-35c2-42d9-89cb-a70fda196506" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_d1548b45-5f6a-4baa-80d1-69b69fe8b038" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_8c93f82c-35c2-42d9-89cb-a70fda196506" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_d1548b45-5f6a-4baa-80d1-69b69fe8b038" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_f735bd4b-cdbb-4d95-a146-65d2d23562d2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseLiability"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_8c93f82c-35c2-42d9-89cb-a70fda196506" xlink:to="loc_us-gaap_OperatingLeaseLiability_f735bd4b-cdbb-4d95-a146-65d2d23562d2" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/IncomeTaxesScheduleofExpenseBenefitforIncomeTaxesDetails" xlink:type="simple" xlink:href="psix-20211231.xsd#IncomeTaxesScheduleofExpenseBenefitforIncomeTaxesDetails"/>
  <link:calculationLink xlink:role="http://powersint.com/role/IncomeTaxesScheduleofExpenseBenefitforIncomeTaxesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_c57310a9-604a-41fe-b95c-182e09e8b990" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CurrentIncomeTaxExpenseBenefit"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrentFederalTaxExpenseBenefit_d3e4e134-e07a-42fb-9700-d56cf6d3d3d9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CurrentFederalTaxExpenseBenefit"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_c57310a9-604a-41fe-b95c-182e09e8b990" xlink:to="loc_us-gaap_CurrentFederalTaxExpenseBenefit_d3e4e134-e07a-42fb-9700-d56cf6d3d3d9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrentStateAndLocalTaxExpenseBenefit_ebc79539-c82d-49ab-bebb-077cdda68167" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CurrentStateAndLocalTaxExpenseBenefit"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_c57310a9-604a-41fe-b95c-182e09e8b990" xlink:to="loc_us-gaap_CurrentStateAndLocalTaxExpenseBenefit_ebc79539-c82d-49ab-bebb-077cdda68167" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrentForeignTaxExpenseBenefit_ac3f722b-dc7f-497a-9725-a30c742bf708" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CurrentForeignTaxExpenseBenefit"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_c57310a9-604a-41fe-b95c-182e09e8b990" xlink:to="loc_us-gaap_CurrentForeignTaxExpenseBenefit_ac3f722b-dc7f-497a-9725-a30c742bf708" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_8650f721-455f-4f11-972a-f00850fbb72b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFederalIncomeTaxExpenseBenefit_226e4551-b91a-471d-9921-542678bb4082" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredFederalIncomeTaxExpenseBenefit"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_8650f721-455f-4f11-972a-f00850fbb72b" xlink:to="loc_us-gaap_DeferredFederalIncomeTaxExpenseBenefit_226e4551-b91a-471d-9921-542678bb4082" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_98d0f415-1a02-43f1-84bd-047209d4c52f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_8650f721-455f-4f11-972a-f00850fbb72b" xlink:to="loc_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_98d0f415-1a02-43f1-84bd-047209d4c52f" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/IncomeTaxesReconciliationofEffectiveTaxRatetotheStatutoryRateDetails" xlink:type="simple" xlink:href="psix-20211231.xsd#IncomeTaxesReconciliationofEffectiveTaxRatetotheStatutoryRateDetails"/>
  <link:calculationLink xlink:role="http://powersint.com/role/IncomeTaxesReconciliationofEffectiveTaxRatetotheStatutoryRateDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_84f23bd0-7bfa-41d3-bfb3-0c9369f384d7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EffectiveIncomeTaxRateContinuingOperations"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_ae3c9518-2971-4b26-8ea3-1885fee3ad66" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_84f23bd0-7bfa-41d3-bfb3-0c9369f384d7" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_ae3c9518-2971-4b26-8ea3-1885fee3ad66" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes_1a59d98e-4fd3-403c-92be-4a5f3b3ecd02" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_84f23bd0-7bfa-41d3-bfb3-0c9369f384d7" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes_1a59d98e-4fd3-403c-92be-4a5f3b3ecd02" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_psix_EffectiveIncomeTaxRateReconciliationOtherPermanentDifferencesPercent_0477ea19-a40c-4dc5-91c8-eae8ccc235ba" xlink:href="psix-20211231.xsd#psix_EffectiveIncomeTaxRateReconciliationOtherPermanentDifferencesPercent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_84f23bd0-7bfa-41d3-bfb3-0c9369f384d7" xlink:to="loc_psix_EffectiveIncomeTaxRateReconciliationOtherPermanentDifferencesPercent_0477ea19-a40c-4dc5-91c8-eae8ccc235ba" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTaxCreditsResearch_0744bc97-9a1c-4c86-a98f-e95b6ef3d88e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationTaxCreditsResearch"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_84f23bd0-7bfa-41d3-bfb3-0c9369f384d7" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTaxCreditsResearch_0744bc97-9a1c-4c86-a98f-e95b6ef3d88e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_psix_EffectiveIncomeTaxRateReconciliationTaxCreditNetOfStatuteExpirationsPercent_25a5b00e-b43b-4a9d-bde6-fff9db3f0d99" xlink:href="psix-20211231.xsd#psix_EffectiveIncomeTaxRateReconciliationTaxCreditNetOfStatuteExpirationsPercent"/>
    <link:calculationArc order="5" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_84f23bd0-7bfa-41d3-bfb3-0c9369f384d7" xlink:to="loc_psix_EffectiveIncomeTaxRateReconciliationTaxCreditNetOfStatuteExpirationsPercent_25a5b00e-b43b-4a9d-bde6-fff9db3f0d99" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_psix_EffectiveIncomeTaxRateReconciliationTaxReserveReassessmentPercent_0e30a675-4fb9-4418-bd6a-d84804fb12f3" xlink:href="psix-20211231.xsd#psix_EffectiveIncomeTaxRateReconciliationTaxReserveReassessmentPercent"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_84f23bd0-7bfa-41d3-bfb3-0c9369f384d7" xlink:to="loc_psix_EffectiveIncomeTaxRateReconciliationTaxReserveReassessmentPercent_0e30a675-4fb9-4418-bd6a-d84804fb12f3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance_1037cc69-390c-4c0c-945d-da64efc42bda" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_84f23bd0-7bfa-41d3-bfb3-0c9369f384d7" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance_1037cc69-390c-4c0c-945d-da64efc42bda" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments_34574dd5-3644-4293-9771-29cd9060713b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_84f23bd0-7bfa-41d3-bfb3-0c9369f384d7" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments_34574dd5-3644-4293-9771-29cd9060713b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitPercent_ff135dd5-4164-4c0c-8e36-5ef0376f72ce" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitPercent"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_84f23bd0-7bfa-41d3-bfb3-0c9369f384d7" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitPercent_ff135dd5-4164-4c0c-8e36-5ef0376f72ce" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent_8fe4d696-cb35-4ee3-a3af-f9546a67b115" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent"/>
    <link:calculationArc order="10" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_84f23bd0-7bfa-41d3-bfb3-0c9369f384d7" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent_8fe4d696-cb35-4ee3-a3af-f9546a67b115" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_psix_EffectiveIncomeTaxRateReconciliationCARESActPercent_94c56559-b8c7-4f81-b391-8bfbccf30bed" xlink:href="psix-20211231.xsd#psix_EffectiveIncomeTaxRateReconciliationCARESActPercent"/>
    <link:calculationArc order="11" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_84f23bd0-7bfa-41d3-bfb3-0c9369f384d7" xlink:to="loc_psix_EffectiveIncomeTaxRateReconciliationCARESActPercent_94c56559-b8c7-4f81-b391-8bfbccf30bed" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_1308cbec-fec8-41a6-8be9-ac741f14d9cf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate_d77b7b7c-5969-466d-a40c-27fc2ccb39fa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_1308cbec-fec8-41a6-8be9-ac741f14d9cf" xlink:to="loc_us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate_d77b7b7c-5969-466d-a40c-27fc2ccb39fa" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes_b83d4320-f84c-4856-bf29-5706e457574f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_1308cbec-fec8-41a6-8be9-ac741f14d9cf" xlink:to="loc_us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes_b83d4320-f84c-4856-bf29-5706e457574f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_psix_EffectiveIncomeTaxRateReconciliationOtherPermanentDifferencesAmount_fc504e1f-eea5-438f-a739-bc36bb7e9edb" xlink:href="psix-20211231.xsd#psix_EffectiveIncomeTaxRateReconciliationOtherPermanentDifferencesAmount"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_1308cbec-fec8-41a6-8be9-ac741f14d9cf" xlink:to="loc_psix_EffectiveIncomeTaxRateReconciliationOtherPermanentDifferencesAmount_fc504e1f-eea5-438f-a739-bc36bb7e9edb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationTaxCreditsResearch_efad1b7d-4143-499a-95a2-14df7cc2a775" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxReconciliationTaxCreditsResearch"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_1308cbec-fec8-41a6-8be9-ac741f14d9cf" xlink:to="loc_us-gaap_IncomeTaxReconciliationTaxCreditsResearch_efad1b7d-4143-499a-95a2-14df7cc2a775" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_psix_EffectiveIncomeTaxRateReconciliationTaxCreditNetOfStatuteExpirationsAmount_16de2052-871b-4ec2-aad1-4b3efd469f2e" xlink:href="psix-20211231.xsd#psix_EffectiveIncomeTaxRateReconciliationTaxCreditNetOfStatuteExpirationsAmount"/>
    <link:calculationArc order="5" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_1308cbec-fec8-41a6-8be9-ac741f14d9cf" xlink:to="loc_psix_EffectiveIncomeTaxRateReconciliationTaxCreditNetOfStatuteExpirationsAmount_16de2052-871b-4ec2-aad1-4b3efd469f2e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_psix_EffectiveIncomeTaxRateReconciliationTaxReserveReassessmentAmount_d997d1e3-ff0d-4ed2-8e65-b6cb5dc501e3" xlink:href="psix-20211231.xsd#psix_EffectiveIncomeTaxRateReconciliationTaxReserveReassessmentAmount"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_1308cbec-fec8-41a6-8be9-ac741f14d9cf" xlink:to="loc_psix_EffectiveIncomeTaxRateReconciliationTaxReserveReassessmentAmount_d997d1e3-ff0d-4ed2-8e65-b6cb5dc501e3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance_3d81e8c7-4e9a-4fa4-a694-65176943aa88" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_1308cbec-fec8-41a6-8be9-ac741f14d9cf" xlink:to="loc_us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance_3d81e8c7-4e9a-4fa4-a694-65176943aa88" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationOtherAdjustments_0943ded2-0ec9-4d5a-b199-210e56603df3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxReconciliationOtherAdjustments"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_1308cbec-fec8-41a6-8be9-ac741f14d9cf" xlink:to="loc_us-gaap_IncomeTaxReconciliationOtherAdjustments_0943ded2-0ec9-4d5a-b199-210e56603df3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount_2982c877-b9dd-4d14-842f-b4255932273d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_1308cbec-fec8-41a6-8be9-ac741f14d9cf" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount_2982c877-b9dd-4d14-842f-b4255932273d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationOtherReconcilingItems_30ac17a1-d7af-4fd1-9d97-41d95c98f80d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxReconciliationOtherReconcilingItems"/>
    <link:calculationArc order="10" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_1308cbec-fec8-41a6-8be9-ac741f14d9cf" xlink:to="loc_us-gaap_IncomeTaxReconciliationOtherReconcilingItems_30ac17a1-d7af-4fd1-9d97-41d95c98f80d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_psix_EffectiveIncomeTaxRateReconciliationCARESActAmount_8132321f-02b3-4954-8f03-44254e67ee53" xlink:href="psix-20211231.xsd#psix_EffectiveIncomeTaxRateReconciliationCARESActAmount"/>
    <link:calculationArc order="11" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_1308cbec-fec8-41a6-8be9-ac741f14d9cf" xlink:to="loc_psix_EffectiveIncomeTaxRateReconciliationCARESActAmount_8132321f-02b3-4954-8f03-44254e67ee53" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/IncomeTaxesScheduleofSignificantComponentsoftheDeferredIncomeTaxAssetsandLiabilitiesDetails" xlink:type="simple" xlink:href="psix-20211231.xsd#IncomeTaxesScheduleofSignificantComponentsoftheDeferredIncomeTaxAssetsandLiabilitiesDetails"/>
  <link:calculationLink xlink:role="http://powersint.com/role/IncomeTaxesScheduleofSignificantComponentsoftheDeferredIncomeTaxAssetsandLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilities_31daaf0f-6959-4e04-9bb1-7a809683d1a6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxLiabilities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilities_01efac51-6b17-4214-a3c7-d83600326734" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredIncomeTaxLiabilities"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxLiabilities_31daaf0f-6959-4e04-9bb1-7a809683d1a6" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilities_01efac51-6b17-4214-a3c7-d83600326734" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsNet_ad08998a-e00c-49b8-b817-7324e2eb8e2f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsNet"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxLiabilities_31daaf0f-6959-4e04-9bb1-7a809683d1a6" xlink:to="loc_us-gaap_DeferredTaxAssetsNet_ad08998a-e00c-49b8-b817-7324e2eb8e2f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilities_424b156f-e784-4ce1-9386-809adda9a02e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredIncomeTaxLiabilities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesLeasingArrangements_bb6d9963-993c-46df-bf11-d7eb2ca50dda" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxLiabilitiesLeasingArrangements"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredIncomeTaxLiabilities_424b156f-e784-4ce1-9386-809adda9a02e" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesLeasingArrangements_bb6d9963-993c-46df-bf11-d7eb2ca50dda" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment_62948491-2b2d-44dd-a494-e8fc1858775b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredIncomeTaxLiabilities_424b156f-e784-4ce1-9386-809adda9a02e" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment_62948491-2b2d-44dd-a494-e8fc1858775b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsNet_a38232de-bdf8-4cde-a818-98e191cc1024" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsGross_75147d0c-e910-4904-af18-54feb453bc09" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsGross"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsNet_a38232de-bdf8-4cde-a818-98e191cc1024" xlink:to="loc_us-gaap_DeferredTaxAssetsGross_75147d0c-e910-4904-af18-54feb453bc09" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsValuationAllowance_60f4538d-92ed-4f98-9274-25901a028a18" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowance"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsNet_a38232de-bdf8-4cde-a818-98e191cc1024" xlink:to="loc_us-gaap_DeferredTaxAssetsValuationAllowance_60f4538d-92ed-4f98-9274-25901a028a18" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsGross_587ae161-b2f1-4079-8cfb-a1f5efb61dca" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsGross"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_88fd55eb-1cfe-458e-abbd-af134cd20f2d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwards"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_587ae161-b2f1-4079-8cfb-a1f5efb61dca" xlink:to="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_88fd55eb-1cfe-458e-abbd-af134cd20f2d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsResearch_4b77a7b9-cf80-4f0f-8f95-b6238d134338" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsResearch"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_587ae161-b2f1-4079-8cfb-a1f5efb61dca" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsResearch_4b77a7b9-cf80-4f0f-8f95-b6238d134338" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_psix_DeferredTaxAssetsTaxCreditCarryforwardsOtherState_546f8b73-c10d-4141-b1ad-732ade440166" xlink:href="psix-20211231.xsd#psix_DeferredTaxAssetsTaxCreditCarryforwardsOtherState"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_587ae161-b2f1-4079-8cfb-a1f5efb61dca" xlink:to="loc_psix_DeferredTaxAssetsTaxCreditCarryforwardsOtherState_546f8b73-c10d-4141-b1ad-732ade440166" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsInventory_c5734829-410b-49b9-95e7-3306e5a54795" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsInventory"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_587ae161-b2f1-4079-8cfb-a1f5efb61dca" xlink:to="loc_us-gaap_DeferredTaxAssetsInventory_c5734829-410b-49b9-95e7-3306e5a54795" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts_5f054a65-d9a9-453c-b25f-498c9eaa09ef" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_587ae161-b2f1-4079-8cfb-a1f5efb61dca" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts_5f054a65-d9a9-453c-b25f-498c9eaa09ef" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsWarrantyReserves_8d2a7d24-a828-4aab-89a5-54d9b7d38e0c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsWarrantyReserves"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_587ae161-b2f1-4079-8cfb-a1f5efb61dca" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsWarrantyReserves_8d2a7d24-a828-4aab-89a5-54d9b7d38e0c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation_73d0e47e-0289-40c1-877f-bccf58472cdc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_587ae161-b2f1-4079-8cfb-a1f5efb61dca" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation_73d0e47e-0289-40c1-877f-bccf58472cdc" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsOther_32ffd320-ebe3-4ece-ba35-095495cf7ddb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsOther"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_587ae161-b2f1-4079-8cfb-a1f5efb61dca" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsOther_32ffd320-ebe3-4ece-ba35-095495cf7ddb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost_90ca0bee-c6cb-488d-bf11-423692f19c34" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_587ae161-b2f1-4079-8cfb-a1f5efb61dca" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost_90ca0bee-c6cb-488d-bf11-423692f19c34" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsInProcessResearchAndDevelopment_bfe54793-c7b1-4e4d-b3b6-befb03559dd5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsInProcessResearchAndDevelopment"/>
    <link:calculationArc order="10" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_587ae161-b2f1-4079-8cfb-a1f5efb61dca" xlink:to="loc_us-gaap_DeferredTaxAssetsInProcessResearchAndDevelopment_bfe54793-c7b1-4e4d-b3b6-befb03559dd5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetInterestCarryforward_847dfbc6-74fa-4f10-a9b1-ebdd9764ee7c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetInterestCarryforward"/>
    <link:calculationArc order="11" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_587ae161-b2f1-4079-8cfb-a1f5efb61dca" xlink:to="loc_us-gaap_DeferredTaxAssetInterestCarryforward_847dfbc6-74fa-4f10-a9b1-ebdd9764ee7c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets_e60e632a-92d7-473f-9f5d-2dede3e1c7d7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets"/>
    <link:calculationArc order="12" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_587ae161-b2f1-4079-8cfb-a1f5efb61dca" xlink:to="loc_us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets_e60e632a-92d7-473f-9f5d-2dede3e1c7d7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsDeferredIncome_d484c0b9-0f2a-4715-907c-b43cc7667326" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsDeferredIncome"/>
    <link:calculationArc order="13" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_587ae161-b2f1-4079-8cfb-a1f5efb61dca" xlink:to="loc_us-gaap_DeferredTaxAssetsDeferredIncome_d484c0b9-0f2a-4715-907c-b43cc7667326" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_psix_DeferredTaxAssetsOperatingLeaseLiability_fa29a190-0ee5-4c8a-9a79-a8cd05c8a976" xlink:href="psix-20211231.xsd#psix_DeferredTaxAssetsOperatingLeaseLiability"/>
    <link:calculationArc order="14" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_587ae161-b2f1-4079-8cfb-a1f5efb61dca" xlink:to="loc_psix_DeferredTaxAssetsOperatingLeaseLiability_fa29a190-0ee5-4c8a-9a79-a8cd05c8a976" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOther_627466fb-d19b-4046-a895-5477b8381de3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsOther"/>
    <link:calculationArc order="15" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_587ae161-b2f1-4079-8cfb-a1f5efb61dca" xlink:to="loc_us-gaap_DeferredTaxAssetsOther_627466fb-d19b-4046-a895-5477b8381de3" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/EarningsLossPerShareDetails" xlink:type="simple" xlink:href="psix-20211231.xsd#EarningsLossPerShareDetails"/>
  <link:calculationLink xlink:role="http://powersint.com/role/EarningsLossPerShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_fbb6cfc0-7c3d-46a9-a5b0-533e7dd4d12b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_af130387-902a-489f-a28e-0d74d9c0e0db" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_fbb6cfc0-7c3d-46a9-a5b0-533e7dd4d12b" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_af130387-902a-489f-a28e-0d74d9c0e0db" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment_028f408e-e199-45b0-a0a6-f1996a89e33a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_fbb6cfc0-7c3d-46a9-a5b0-533e7dd4d12b" xlink:to="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment_028f408e-e199-45b0-a0a6-f1996a89e33a" xlink:type="arc"/>
  </link:calculationLink>
</link:linkbase>
