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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2024 Workiva-->
<!--r:3eeab596-48cc-4b3e-aa2b-fce62e69f5f2,g:e074fa9c-6b90-4be0-914b-59dd728d795b-->
<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/CONDENSEDCONSOLIDATEDBALANCESHEETS" xlink:type="simple" xlink:href="psix-20240630.xsd#CONDENSEDCONSOLIDATEDBALANCESHEETS"/>
  <link:calculationLink xlink:role="http://powersint.com/role/CONDENSEDCONSOLIDATEDBALANCESHEETS" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_8bdd7403-e1cd-4383-a269-93cbbed9c51e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetsCurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_642396bd-1ee9-4373-8c46-686af263f0e9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_AssetsCurrent_8bdd7403-e1cd-4383-a269-93cbbed9c51e" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_642396bd-1ee9-4373-8c46-686af263f0e9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_3250e263-822e-4c94-83b6-f7feee1ec284" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_8bdd7403-e1cd-4383-a269-93cbbed9c51e" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_3250e263-822e-4c94-83b6-f7feee1ec284" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesReceivable_66fc7a0c-b423-46f7-a572-86bb0e3f39e9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeTaxesReceivable"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_8bdd7403-e1cd-4383-a269-93cbbed9c51e" xlink:to="loc_us-gaap_IncomeTaxesReceivable_66fc7a0c-b423-46f7-a572-86bb0e3f39e9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryNet_4d0ccd52-1410-4399-ba75-a54403655d58" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InventoryNet"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_8bdd7403-e1cd-4383-a269-93cbbed9c51e" xlink:to="loc_us-gaap_InventoryNet_4d0ccd52-1410-4399-ba75-a54403655d58" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashCurrent_a4ef6a23-71a8-45fa-9d0f-620fcd5d03cd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedCashCurrent"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_8bdd7403-e1cd-4383-a269-93cbbed9c51e" xlink:to="loc_us-gaap_RestrictedCashCurrent_a4ef6a23-71a8-45fa-9d0f-620fcd5d03cd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_443d88a0-88a2-4cda-a5f9-d786aa5e2aa5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_8bdd7403-e1cd-4383-a269-93cbbed9c51e" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_443d88a0-88a2-4cda-a5f9-d786aa5e2aa5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_35d29823-ad39-40df-8882-27f1ac7aab0f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_4364f213-feee-475a-8d88-affe3cc920d6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_35d29823-ad39-40df-8882-27f1ac7aab0f" xlink:to="loc_us-gaap_Liabilities_4364f213-feee-475a-8d88-affe3cc920d6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_e51b61ef-08f4-4ad0-92f2-d4a777cc5ea4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_35d29823-ad39-40df-8882-27f1ac7aab0f" xlink:to="loc_us-gaap_StockholdersEquity_e51b61ef-08f4-4ad0-92f2-d4a777cc5ea4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingencies_b123632f-bd16-4552-93d9-c373a4a58936" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommitmentsAndContingencies"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_35d29823-ad39-40df-8882-27f1ac7aab0f" xlink:to="loc_us-gaap_CommitmentsAndContingencies_b123632f-bd16-4552-93d9-c373a4a58936" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_ecbf33dd-3bf4-4127-83a2-c48dbdca7db6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_f34230e0-4f2f-4542-af33-3ed607085372" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_LiabilitiesCurrent_ecbf33dd-3bf4-4127-83a2-c48dbdca7db6" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_f34230e0-4f2f-4542-af33-3ed607085372" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherShortTermBorrowings_d489db23-f0e8-4938-bcc6-7bd21db0fff7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherShortTermBorrowings"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_ecbf33dd-3bf4-4127-83a2-c48dbdca7db6" xlink:to="loc_us-gaap_OtherShortTermBorrowings_d489db23-f0e8-4938-bcc6-7bd21db0fff7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAccruedLiabilitiesCurrent_6ddfbc24-28fe-4161-a763-0c144c66ee5d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherAccruedLiabilitiesCurrent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_ecbf33dd-3bf4-4127-83a2-c48dbdca7db6" xlink:to="loc_us-gaap_OtherAccruedLiabilitiesCurrent_6ddfbc24-28fe-4161-a763-0c144c66ee5d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_ec95d7df-0a07-4f20-853b-18c935f14910" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_ecbf33dd-3bf4-4127-83a2-c48dbdca7db6" xlink:to="loc_us-gaap_LongTermDebtCurrent_ec95d7df-0a07-4f20-853b-18c935f14910" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LinesOfCreditCurrent_ac4c7dc9-d404-47a0-931c-6df996aaa40a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LinesOfCreditCurrent"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_ecbf33dd-3bf4-4127-83a2-c48dbdca7db6" xlink:to="loc_us-gaap_LinesOfCreditCurrent_ac4c7dc9-d404-47a0-931c-6df996aaa40a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent_0aaa1079-e606-44f0-b70c-d0f9e3238a91" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccountsPayableCurrent"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_ecbf33dd-3bf4-4127-83a2-c48dbdca7db6" xlink:to="loc_us-gaap_AccountsPayableCurrent_0aaa1079-e606-44f0-b70c-d0f9e3238a91" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityCurrent_f2639a8d-c7e1-4aa9-8532-7ed137b3f008" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinanceLeaseLiabilityCurrent"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_ecbf33dd-3bf4-4127-83a2-c48dbdca7db6" xlink:to="loc_us-gaap_FinanceLeaseLiabilityCurrent_f2639a8d-c7e1-4aa9-8532-7ed137b3f008" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_bb210b7f-07e7-4192-8d28-f2d5cd444d5c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Assets"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_b18c60eb-94cc-4301-9e9b-61bd08df75e2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_bb210b7f-07e7-4192-8d28-f2d5cd444d5c" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_b18c60eb-94cc-4301-9e9b-61bd08df75e2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_7bd4be36-686c-4711-b368-bddbb25f337e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_bb210b7f-07e7-4192-8d28-f2d5cd444d5c" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_7bd4be36-686c-4711-b368-bddbb25f337e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_781ca322-580c-4d38-9e2d-10cf5cd572c1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Goodwill"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_bb210b7f-07e7-4192-8d28-f2d5cd444d5c" xlink:to="loc_us-gaap_Goodwill_781ca322-580c-4d38-9e2d-10cf5cd572c1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_28ff390d-6a03-41ae-b48b-06ebd493514b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherAssetsNoncurrent"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_bb210b7f-07e7-4192-8d28-f2d5cd444d5c" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_28ff390d-6a03-41ae-b48b-06ebd493514b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_cd654231-22ed-40b4-8ac7-22b350d220de" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_bb210b7f-07e7-4192-8d28-f2d5cd444d5c" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_cd654231-22ed-40b4-8ac7-22b350d220de" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_2b8bb780-ec09-4214-9405-ba5482b81901" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetsCurrent"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_bb210b7f-07e7-4192-8d28-f2d5cd444d5c" xlink:to="loc_us-gaap_AssetsCurrent_2b8bb780-ec09-4214-9405-ba5482b81901" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_4afada5c-92f0-4858-841e-5196f8ba5421" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockValue_2e4de0a4-afc8-4bdb-8268-c5660210a264" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_4afada5c-92f0-4858-841e-5196f8ba5421" xlink:to="loc_us-gaap_PreferredStockValue_2e4de0a4-afc8-4bdb-8268-c5660210a264" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_cb81dc7d-3202-4575-a557-8789ea256d7e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_4afada5c-92f0-4858-841e-5196f8ba5421" xlink:to="loc_us-gaap_CommonStockValue_cb81dc7d-3202-4575-a557-8789ea256d7e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapital_13397275-492b-4105-8258-5f8afb325a18" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_4afada5c-92f0-4858-841e-5196f8ba5421" xlink:to="loc_us-gaap_AdditionalPaidInCapital_13397275-492b-4105-8258-5f8afb325a18" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_b337927c-b10c-419c-923b-b649ee1c0dd2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_4afada5c-92f0-4858-841e-5196f8ba5421" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_b337927c-b10c-419c-923b-b649ee1c0dd2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonValue_35d53e31-ccf5-4851-910d-6226a0397879" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TreasuryStockCommonValue"/>
    <link:calculationArc order="5" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_4afada5c-92f0-4858-841e-5196f8ba5421" xlink:to="loc_us-gaap_TreasuryStockCommonValue_35d53e31-ccf5-4851-910d-6226a0397879" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_9ad7ae82-7a97-4267-93ba-16d7ed41b152" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Liabilities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_c1aa2fa0-216d-4d24-b9ba-2abd04764012" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_9ad7ae82-7a97-4267-93ba-16d7ed41b152" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_c1aa2fa0-216d-4d24-b9ba-2abd04764012" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_a22c1bc0-8344-4b08-a016-f75223ed6f55" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_9ad7ae82-7a97-4267-93ba-16d7ed41b152" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_a22c1bc0-8344-4b08-a016-f75223ed6f55" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_d60091d2-83c7-4e73-b2cc-3429bb8a8b2a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherLiabilitiesNoncurrent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_9ad7ae82-7a97-4267-93ba-16d7ed41b152" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_d60091d2-83c7-4e73-b2cc-3429bb8a8b2a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_f4cb5627-8069-4d47-8a37-53998fc26cdd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_9ad7ae82-7a97-4267-93ba-16d7ed41b152" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_f4cb5627-8069-4d47-8a37-53998fc26cdd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityNoncurrent_5a788d12-a593-4fbf-8624-21fff4cb497b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinanceLeaseLiabilityNoncurrent"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_9ad7ae82-7a97-4267-93ba-16d7ed41b152" xlink:to="loc_us-gaap_FinanceLeaseLiabilityNoncurrent_5a788d12-a593-4fbf-8624-21fff4cb497b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityNoncurrent_7f268ae6-9d09-4847-99d5-4504e9a85fcc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractWithCustomerLiabilityNoncurrent"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_9ad7ae82-7a97-4267-93ba-16d7ed41b152" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityNoncurrent_7f268ae6-9d09-4847-99d5-4504e9a85fcc" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_5420b509-d93a-41d8-9832-38473db87657" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_9ad7ae82-7a97-4267-93ba-16d7ed41b152" xlink:to="loc_us-gaap_LiabilitiesCurrent_5420b509-d93a-41d8-9832-38473db87657" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFINCOMEUNAUDITED" xlink:type="simple" xlink:href="psix-20240630.xsd#CONDENSEDCONSOLIDATEDSTATEMENTSOFINCOMEUNAUDITED"/>
  <link:calculationLink xlink:role="http://powersint.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFINCOMEUNAUDITED" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpenses_1d033739-fcf2-49db-826e-37dac0b6a548" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingExpenses"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_bec4c707-687d-4831-9da8-9a7fd491020e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_1d033739-fcf2-49db-826e-37dac0b6a548" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_bec4c707-687d-4831-9da8-9a7fd491020e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingAndMarketingExpense_f80e534f-db65-48b8-96cd-230224c9d73e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_1d033739-fcf2-49db-826e-37dac0b6a548" xlink:to="loc_us-gaap_SellingAndMarketingExpense_f80e534f-db65-48b8-96cd-230224c9d73e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_c4402f68-f3ad-4004-9d1a-43475fe11f8a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_1d033739-fcf2-49db-826e-37dac0b6a548" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_c4402f68-f3ad-4004-9d1a-43475fe11f8a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_def4fde0-9350-42c2-a535-242aa5b608e2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_880c3336-e4a4-442f-bc2c-f5c23dae6814" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_def4fde0-9350-42c2-a535-242aa5b608e2" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_880c3336-e4a4-442f-bc2c-f5c23dae6814" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_a8e941ad-8852-4c2e-90dc-77b0ff151088" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_def4fde0-9350-42c2-a535-242aa5b608e2" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_a8e941ad-8852-4c2e-90dc-77b0ff151088" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_55596eda-ceed-4456-a371-253e12d3cc2f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_f4d62c12-2301-4266-8b72-14ca4df6a04c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_55596eda-ceed-4456-a371-253e12d3cc2f" xlink:to="loc_us-gaap_OperatingIncomeLoss_f4d62c12-2301-4266-8b72-14ca4df6a04c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseNonoperating_4f770181-2528-4714-aba0-86d9e40dec84" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestExpenseNonoperating"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_55596eda-ceed-4456-a371-253e12d3cc2f" xlink:to="loc_us-gaap_InterestExpenseNonoperating_4f770181-2528-4714-aba0-86d9e40dec84" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossProfit_f2ce9669-9085-400b-b633-979f7ec5b5a1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GrossProfit"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_d638c966-7904-4cfd-bda2-ead4788897c2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_f2ce9669-9085-400b-b633-979f7ec5b5a1" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_d638c966-7904-4cfd-bda2-ead4788897c2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_8c98ce7a-7cf7-46fe-bc0e-78c0d481985b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_f2ce9669-9085-400b-b633-979f7ec5b5a1" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_8c98ce7a-7cf7-46fe-bc0e-78c0d481985b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_8bfe34d4-bf30-4630-91b8-8b3f88768ca8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossProfit_83e155c4-f004-4e92-b002-a7d3e7748aa9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_8bfe34d4-bf30-4630-91b8-8b3f88768ca8" xlink:to="loc_us-gaap_GrossProfit_83e155c4-f004-4e92-b002-a7d3e7748aa9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpenses_9befd1e0-881e-4dd9-9046-9c2add5a820d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_8bfe34d4-bf30-4630-91b8-8b3f88768ca8" xlink:to="loc_us-gaap_OperatingExpenses_9befd1e0-881e-4dd9-9046-9c2add5a820d" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFCASHFLOWSUNAUDITED" xlink:type="simple" xlink:href="psix-20240630.xsd#CONDENSEDCONSOLIDATEDSTATEMENTSOFCASHFLOWSUNAUDITED"/>
  <link:calculationLink xlink:role="http://powersint.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFCASHFLOWSUNAUDITED" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_51395396-0212-45e2-b77e-6aa3a6474300" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_50292552-d6c2-4dce-8867-a84b9681dc35" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_51395396-0212-45e2-b77e-6aa3a6474300" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_50292552-d6c2-4dce-8867-a84b9681dc35" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_7fe7bab6-492a-4e01-bd14-7f0ad3e7d6aa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_51395396-0212-45e2-b77e-6aa3a6474300" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_7fe7bab6-492a-4e01-bd14-7f0ad3e7d6aa" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_20a07fc3-1cd1-47cf-9753-8970412963eb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_51395396-0212-45e2-b77e-6aa3a6474300" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_20a07fc3-1cd1-47cf-9753-8970412963eb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_dc168826-f895-4765-ba15-18bbf7bf4e94" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_4f3bfd85-d1f2-4b6c-9f32-f604081d0cf4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_dc168826-f895-4765-ba15-18bbf7bf4e94" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_4f3bfd85-d1f2-4b6c-9f32-f604081d0cf4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashCurrent_2c91a0e4-a511-4795-9184-cb219ac126cf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_dc168826-f895-4765-ba15-18bbf7bf4e94" xlink:to="loc_us-gaap_RestrictedCashCurrent_2c91a0e4-a511-4795-9184-cb219ac126cf" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_6ec7f286-0d80-48fb-beca-7c41a4d2a1c2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLongTermDebtAndCapitalSecurities_9a376d0a-a272-418e-bbe7-1a95e0d441e5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RepaymentsOfLongTermDebtAndCapitalSecurities"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_6ec7f286-0d80-48fb-beca-7c41a4d2a1c2" xlink:to="loc_us-gaap_RepaymentsOfLongTermDebtAndCapitalSecurities_9a376d0a-a272-418e-bbe7-1a95e0d441e5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDebtIssuanceCosts_0298bda0-e744-48c5-9c49-9b75fd15a7a5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsOfDebtIssuanceCosts"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_6ec7f286-0d80-48fb-beca-7c41a4d2a1c2" xlink:to="loc_us-gaap_PaymentsOfDebtIssuanceCosts_0298bda0-e744-48c5-9c49-9b75fd15a7a5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfShortTermDebt_0807850f-b651-47a5-935d-0bf4f3808136" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RepaymentsOfShortTermDebt"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_6ec7f286-0d80-48fb-beca-7c41a4d2a1c2" xlink:to="loc_us-gaap_RepaymentsOfShortTermDebt_0807850f-b651-47a5-935d-0bf4f3808136" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_b14e68be-10f4-4a51-a540-b19b33d8e4ba" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_6ec7f286-0d80-48fb-beca-7c41a4d2a1c2" xlink:to="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_b14e68be-10f4-4a51-a540-b19b33d8e4ba" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b62d62c9-4469-4107-974f-60ccb0b63fe8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfFinancingCosts_ce2ed09d-02f6-4efa-852f-fa7cbf7858ca" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AmortizationOfFinancingCosts"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b62d62c9-4469-4107-974f-60ccb0b63fe8" xlink:to="loc_us-gaap_AmortizationOfFinancingCosts_ce2ed09d-02f6-4efa-852f-fa7cbf7858ca" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherOperatingActivitiesCashFlowStatement_190c3a79-09c9-4edd-81c4-f8ebae5b950e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherOperatingActivitiesCashFlowStatement"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b62d62c9-4469-4107-974f-60ccb0b63fe8" xlink:to="loc_us-gaap_OtherOperatingActivitiesCashFlowStatement_190c3a79-09c9-4edd-81c4-f8ebae5b950e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentLiabilities_5ef01426-d56f-4623-99e6-cf7c9e9b3ce8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInOtherNoncurrentLiabilities"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b62d62c9-4469-4107-974f-60ccb0b63fe8" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentLiabilities_5ef01426-d56f-4623-99e6-cf7c9e9b3ce8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxesAndTaxCredits_c536e09e-cd26-45dc-adbd-cc97147b868e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredIncomeTaxesAndTaxCredits"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b62d62c9-4469-4107-974f-60ccb0b63fe8" xlink:to="loc_us-gaap_DeferredIncomeTaxesAndTaxCredits_c536e09e-cd26-45dc-adbd-cc97147b868e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_psix_IncreaseDecreaseInAllowanceForObsolescence_4e6d59d4-1b07-4de7-9486-bc586badf1c1" xlink:href="psix-20240630.xsd#psix_IncreaseDecreaseInAllowanceForObsolescence"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b62d62c9-4469-4107-974f-60ccb0b63fe8" xlink:to="loc_psix_IncreaseDecreaseInAllowanceForObsolescence_4e6d59d4-1b07-4de7-9486-bc586badf1c1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccruedLiabilities_471e8108-851a-4971-84c8-d323e391c53f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInAccruedLiabilities"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b62d62c9-4469-4107-974f-60ccb0b63fe8" xlink:to="loc_us-gaap_IncreaseDecreaseInAccruedLiabilities_471e8108-851a-4971-84c8-d323e391c53f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_3b5d645d-da5b-4ca8-bddf-ce8ebd8969b9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets"/>
    <link:calculationArc order="7" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b62d62c9-4469-4107-974f-60ccb0b63fe8" xlink:to="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_3b5d645d-da5b-4ca8-bddf-ce8ebd8969b9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_be3099c2-75f9-45ce-a659-3369b3423fd9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Depreciation"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b62d62c9-4469-4107-974f-60ccb0b63fe8" xlink:to="loc_us-gaap_Depreciation_be3099c2-75f9-45ce-a659-3369b3423fd9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_9650d3a5-5173-4af7-8aca-dca9e9ed4f44" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLoss"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b62d62c9-4469-4107-974f-60ccb0b63fe8" xlink:to="loc_us-gaap_NetIncomeLoss_9650d3a5-5173-4af7-8aca-dca9e9ed4f44" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProvisionForDoubtfulAccounts_45453fd0-6612-4fe3-b7e2-84482f849ae1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProvisionForDoubtfulAccounts"/>
    <link:calculationArc order="10" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b62d62c9-4469-4107-974f-60ccb0b63fe8" xlink:to="loc_us-gaap_ProvisionForDoubtfulAccounts_45453fd0-6612-4fe3-b7e2-84482f849ae1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_fa40e2a4-48e7-4317-adb5-b8e919eb8991" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:calculationArc order="11" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b62d62c9-4469-4107-974f-60ccb0b63fe8" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_fa40e2a4-48e7-4317-adb5-b8e919eb8991" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_50c5a351-d171-4dec-8793-3a14b2a63261" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_b62d62c9-4469-4107-974f-60ccb0b63fe8" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_50c5a351-d171-4dec-8793-3a14b2a63261" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInIncomeTaxesPayableNetOfIncomeTaxesReceivable_56278f77-8728-4fa9-930b-9bb958c4b13c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInIncomeTaxesPayableNetOfIncomeTaxesReceivable"/>
    <link:calculationArc order="13" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b62d62c9-4469-4107-974f-60ccb0b63fe8" xlink:to="loc_us-gaap_IncreaseDecreaseInIncomeTaxesPayableNetOfIncomeTaxesReceivable_56278f77-8728-4fa9-930b-9bb958c4b13c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayableTrade_acf1beec-47b2-4707-9050-c4c4e1cfcbd1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInAccountsPayableTrade"/>
    <link:calculationArc order="14" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b62d62c9-4469-4107-974f-60ccb0b63fe8" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayableTrade_acf1beec-47b2-4707-9050-c4c4e1cfcbd1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInInventories_6ed89808-bd40-40a7-bf17-f0c4472cc4f0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInInventories"/>
    <link:calculationArc order="15" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b62d62c9-4469-4107-974f-60ccb0b63fe8" xlink:to="loc_us-gaap_IncreaseDecreaseInInventories_6ed89808-bd40-40a7-bf17-f0c4472cc4f0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_32516ead-47a9-43ed-b462-d8b3a32d4dd6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensation"/>
    <link:calculationArc order="16" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b62d62c9-4469-4107-974f-60ccb0b63fe8" xlink:to="loc_us-gaap_ShareBasedCompensation_32516ead-47a9-43ed-b462-d8b3a32d4dd6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_beb74505-2d11-4575-a74d-c433f46823f8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForCapitalImprovements_76ef88ff-b9b7-4512-a75b-b89521cc016e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsForCapitalImprovements"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_beb74505-2d11-4575-a74d-c433f46823f8" xlink:to="loc_us-gaap_PaymentsForCapitalImprovements_76ef88ff-b9b7-4512-a75b-b89521cc016e" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/SummaryofSignificantAccountingPoliciesandOtherInformationScheduleofInventoryCurrentDetails" xlink:type="simple" xlink:href="psix-20240630.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_2e60b720-a51d-4c63-bbf2-afdd37296e01" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InventoryNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryGross_0459ca31-6999-480e-8c71-6a04db596a5d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_2e60b720-a51d-4c63-bbf2-afdd37296e01" xlink:to="loc_us-gaap_InventoryGross_0459ca31-6999-480e-8c71-6a04db596a5d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryValuationReserves_66e370ca-1384-4f4c-a55c-bd05456f51e4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_2e60b720-a51d-4c63-bbf2-afdd37296e01" xlink:to="loc_us-gaap_InventoryValuationReserves_66e370ca-1384-4f4c-a55c-bd05456f51e4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryGross_4abc69b2-9490-4c78-be89-8ec66e22fa30" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InventoryGross"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryRawMaterials_5be3ca19-f627-48d2-aa98-37015ad90abf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_4abc69b2-9490-4c78-be89-8ec66e22fa30" xlink:to="loc_us-gaap_InventoryRawMaterials_5be3ca19-f627-48d2-aa98-37015ad90abf" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryWorkInProcess_232f04d4-55d2-48f7-bb34-caed1e82bc75" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_4abc69b2-9490-4c78-be89-8ec66e22fa30" xlink:to="loc_us-gaap_InventoryWorkInProcess_232f04d4-55d2-48f7-bb34-caed1e82bc75" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryFinishedGoods_dfde8063-32bc-47bd-bd74-214c9a7142a1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_4abc69b2-9490-4c78-be89-8ec66e22fa30" xlink:to="loc_us-gaap_InventoryFinishedGoods_dfde8063-32bc-47bd-bd74-214c9a7142a1" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/SummaryofSignificantAccountingPoliciesandOtherInformationScheduleofOtherAccruedLiabilitiesDetails" xlink:type="simple" xlink:href="psix-20240630.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_242f9e1c-998f-4f25-a2c9-6c3e53eca68d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccruedLiabilitiesAndOtherLiabilities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPayableCurrent_2b5c5bd0-26e2-46eb-bc26-53471b2a0f52" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestPayableCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilities_242f9e1c-998f-4f25-a2c9-6c3e53eca68d" xlink:to="loc_us-gaap_InterestPayableCurrent_2b5c5bd0-26e2-46eb-bc26-53471b2a0f52" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationReserve_f35ccb91-79d0-427d-a2d0-4307ebee6c11" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_242f9e1c-998f-4f25-a2c9-6c3e53eca68d" xlink:to="loc_us-gaap_LitigationReserve_f35ccb91-79d0-427d-a2d0-4307ebee6c11" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StandardProductWarrantyAccrualCurrent_d7e37566-d46f-4d31-9fbe-a60bc2b37c29" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StandardProductWarrantyAccrualCurrent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilities_242f9e1c-998f-4f25-a2c9-6c3e53eca68d" xlink:to="loc_us-gaap_StandardProductWarrantyAccrualCurrent_d7e37566-d46f-4d31-9fbe-a60bc2b37c29" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherSundryLiabilitiesCurrent_6ad89211-effe-4b46-b015-daacc941f5fd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherSundryLiabilitiesCurrent"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilities_242f9e1c-998f-4f25-a2c9-6c3e53eca68d" xlink:to="loc_us-gaap_OtherSundryLiabilitiesCurrent_6ad89211-effe-4b46-b015-daacc941f5fd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_70211330-e974-430d-8e90-5c9751b7b1cb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilities_242f9e1c-998f-4f25-a2c9-6c3e53eca68d" xlink:to="loc_us-gaap_ContractWithCustomerLiability_70211330-e974-430d-8e90-5c9751b7b1cb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedEmployeeBenefitsCurrentAndNoncurrent_92eafd4b-555c-49dd-9145-b6cd29185cb8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccruedEmployeeBenefitsCurrentAndNoncurrent"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilities_242f9e1c-998f-4f25-a2c9-6c3e53eca68d" xlink:to="loc_us-gaap_AccruedEmployeeBenefitsCurrentAndNoncurrent_92eafd4b-555c-49dd-9145-b6cd29185cb8" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/SummaryofSignificantAccountingPoliciesandOtherInformationScheduleofProductWarrantyLiabilityDetails" xlink:type="simple" xlink:href="psix-20240630.xsd#SummaryofSignificantAccountingPoliciesandOtherInformationScheduleofProductWarrantyLiabilityDetails"/>
  <link:calculationLink xlink:role="http://powersint.com/role/SummaryofSignificantAccountingPoliciesandOtherInformationScheduleofProductWarrantyLiabilityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StandardProductWarrantyAccrual_afcadba9-53f3-454e-9b3d-6ed7212680ea" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StandardProductWarrantyAccrual"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StandardProductWarrantyAccrualNoncurrent_be1d8bd2-8ccc-4c6e-addd-ac1b5b9d85c9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_afcadba9-53f3-454e-9b3d-6ed7212680ea" xlink:to="loc_us-gaap_StandardProductWarrantyAccrualNoncurrent_be1d8bd2-8ccc-4c6e-addd-ac1b5b9d85c9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StandardProductWarrantyAccrualCurrent_624c3885-8865-44dd-a4fb-6b129e5ce446" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_afcadba9-53f3-454e-9b3d-6ed7212680ea" xlink:to="loc_us-gaap_StandardProductWarrantyAccrualCurrent_624c3885-8865-44dd-a4fb-6b129e5ce446" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/RevenueScheduleofContractBalancesDetails" xlink:type="simple" xlink:href="psix-20240630.xsd#RevenueScheduleofContractBalancesDetails"/>
  <link:calculationLink xlink:role="http://powersint.com/role/RevenueScheduleofContractBalancesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_psix_ContractWithCustomerAssetLiability_275f21e8-8f74-4e4a-8b22-1d560f5b7168" xlink:href="psix-20240630.xsd#psix_ContractWithCustomerAssetLiability"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerAssetNetCurrent_c36c4498-0ae3-48e1-aecc-9990ae7fa59d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractWithCustomerAssetNetCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_psix_ContractWithCustomerAssetLiability_275f21e8-8f74-4e4a-8b22-1d560f5b7168" xlink:to="loc_us-gaap_ContractWithCustomerAssetNetCurrent_c36c4498-0ae3-48e1-aecc-9990ae7fa59d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityCurrent_4cab93cb-8aaf-461a-ac07-df48e32a0542" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_275f21e8-8f74-4e4a-8b22-1d560f5b7168" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityCurrent_4cab93cb-8aaf-461a-ac07-df48e32a0542" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityNoncurrent_8dcd1b60-53ca-49a2-96de-fa93f0c825a3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_275f21e8-8f74-4e4a-8b22-1d560f5b7168" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityNoncurrent_8dcd1b60-53ca-49a2-96de-fa93f0c825a3" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/PropertyPlantandEquipmentDetails" xlink:type="simple" xlink:href="psix-20240630.xsd#PropertyPlantandEquipmentDetails"/>
  <link:calculationLink xlink:role="http://powersint.com/role/PropertyPlantandEquipmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_f9bd546d-260c-4afc-a271-550f5a666fb9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_3a90f981-7b11-4b5e-b7cc-265914ac2669" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_f9bd546d-260c-4afc-a271-550f5a666fb9" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_3a90f981-7b11-4b5e-b7cc-265914ac2669" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_00997d74-6931-4ef3-9192-0bc06df98eaf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_f9bd546d-260c-4afc-a271-550f5a666fb9" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_00997d74-6931-4ef3-9192-0bc06df98eaf" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/GoodwillandOtherIntangiblesScheduleofFiniteLivedIntangibleAssetsDetails" xlink:type="simple" xlink:href="psix-20240630.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_72f0650a-e2e9-4adc-b91d-1c1196496026" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_42ef9edb-2265-4b82-a232-e436b6163dc0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_72f0650a-e2e9-4adc-b91d-1c1196496026" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_42ef9edb-2265-4b82-a232-e436b6163dc0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_a9c25896-a8d2-40cc-8458-b7b5aa9ae5bb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_72f0650a-e2e9-4adc-b91d-1c1196496026" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_a9c25896-a8d2-40cc-8458-b7b5aa9ae5bb" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/DebtScheduleofDebtDetails" xlink:type="simple" xlink:href="psix-20240630.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_7fab6458-03d7-4210-ba10-b1f79fc3cc5d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligations"/>
    <link:loc xlink:type="locator" xlink:label="loc_psix_FinanceLeaseLiabilityAndOtherLongTermDebt_b77418d9-ccdf-40b6-99f2-06bb7d22520d" xlink:href="psix-20240630.xsd#psix_FinanceLeaseLiabilityAndOtherLongTermDebt"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_7fab6458-03d7-4210-ba10-b1f79fc3cc5d" xlink:to="loc_psix_FinanceLeaseLiabilityAndOtherLongTermDebt_b77418d9-ccdf-40b6-99f2-06bb7d22520d" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/DebtScheduleofDebtDetails_1" xlink:type="simple" xlink:href="psix-20240630.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_33ef133d-cb00-4aee-8743-9174c941a19f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligations"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent_22b60a1a-0deb-4dcc-a702-ef3c2475fca3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_33ef133d-cb00-4aee-8743-9174c941a19f" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent_22b60a1a-0deb-4dcc-a702-ef3c2475fca3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_psix_LongTermDebtExcludingNotesPayable_5970f020-eb90-4cd7-a1df-a353103563b8" xlink:href="psix-20240630.xsd#psix_LongTermDebtExcludingNotesPayable"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_33ef133d-cb00-4aee-8743-9174c941a19f" xlink:to="loc_psix_LongTermDebtExcludingNotesPayable_5970f020-eb90-4cd7-a1df-a353103563b8" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/OtherNoncurrentLiabilitiesScheduleofLongTermDebtInstrumentsDetails" xlink:type="simple" xlink:href="psix-20240630.xsd#OtherNoncurrentLiabilitiesScheduleofLongTermDebtInstrumentsDetails"/>
  <link:calculationLink xlink:role="http://powersint.com/role/OtherNoncurrentLiabilitiesScheduleofLongTermDebtInstrumentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_9849d895-b841-443b-8319-8e0b218f8703" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebt"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_9d04fed6-b1f5-412b-a0c9-5d76db714c7e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_9849d895-b841-443b-8319-8e0b218f8703" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_9d04fed6-b1f5-412b-a0c9-5d76db714c7e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscount_ec2f5a86-bc33-45a3-8319-8436b238e0be" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentUnamortizedDiscount"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_9849d895-b841-443b-8319-8e0b218f8703" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscount_ec2f5a86-bc33-45a3-8319-8436b238e0be" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/OtherNoncurrentLiabilitiesScheduleofMaturitiesofLongTermDebtDetails" xlink:type="simple" xlink:href="psix-20240630.xsd#OtherNoncurrentLiabilitiesScheduleofMaturitiesofLongTermDebtDetails"/>
  <link:calculationLink xlink:role="http://powersint.com/role/OtherNoncurrentLiabilitiesScheduleofMaturitiesofLongTermDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfDebtDiscountPremium_f2ccb3ea-7e6d-40e5-b75a-f9bb318b7ab9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AmortizationOfDebtDiscountPremium"/>
    <link:loc xlink:type="locator" xlink:label="loc_psix_AmortizationOfDebtDiscountPremiumRemainderOfFiscalYear_f8740c57-b09f-40ec-962b-c50e0b6760e2" xlink:href="psix-20240630.xsd#psix_AmortizationOfDebtDiscountPremiumRemainderOfFiscalYear"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AmortizationOfDebtDiscountPremium_f2ccb3ea-7e6d-40e5-b75a-f9bb318b7ab9" xlink:to="loc_psix_AmortizationOfDebtDiscountPremiumRemainderOfFiscalYear_f8740c57-b09f-40ec-962b-c50e0b6760e2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_psix_AmortizationOfDebtDiscountPremiumYearThree_0394791f-999a-49fe-9dfc-69c8bf0d1002" xlink:href="psix-20240630.xsd#psix_AmortizationOfDebtDiscountPremiumYearThree"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AmortizationOfDebtDiscountPremium_f2ccb3ea-7e6d-40e5-b75a-f9bb318b7ab9" xlink:to="loc_psix_AmortizationOfDebtDiscountPremiumYearThree_0394791f-999a-49fe-9dfc-69c8bf0d1002" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_psix_AmortizationOfDebtDiscountPremiumYearFour_729496c8-0e69-4da8-80a9-29c5d30db948" xlink:href="psix-20240630.xsd#psix_AmortizationOfDebtDiscountPremiumYearFour"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AmortizationOfDebtDiscountPremium_f2ccb3ea-7e6d-40e5-b75a-f9bb318b7ab9" xlink:to="loc_psix_AmortizationOfDebtDiscountPremiumYearFour_729496c8-0e69-4da8-80a9-29c5d30db948" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_psix_AmortizationOfDebtDiscountPremiumYearTwo_7e22a8b2-705b-42ae-b40f-aaddf6be24ac" xlink:href="psix-20240630.xsd#psix_AmortizationOfDebtDiscountPremiumYearTwo"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AmortizationOfDebtDiscountPremium_f2ccb3ea-7e6d-40e5-b75a-f9bb318b7ab9" xlink:to="loc_psix_AmortizationOfDebtDiscountPremiumYearTwo_7e22a8b2-705b-42ae-b40f-aaddf6be24ac" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_psix_AmortizationOfDebtDiscountPremiumYearOne_8f992ef1-727c-46ad-a904-ca9ac6ef010e" xlink:href="psix-20240630.xsd#psix_AmortizationOfDebtDiscountPremiumYearOne"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AmortizationOfDebtDiscountPremium_f2ccb3ea-7e6d-40e5-b75a-f9bb318b7ab9" xlink:to="loc_psix_AmortizationOfDebtDiscountPremiumYearOne_8f992ef1-727c-46ad-a904-ca9ac6ef010e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_0b1305ee-ee0f-482e-8a6a-105bef196f2a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebt"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths_51800cf6-9e29-4139-ba97-d124a476040e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_LongTermDebt_0b1305ee-ee0f-482e-8a6a-105bef196f2a" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths_51800cf6-9e29-4139-ba97-d124a476040e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour_4d9eebad-16c9-479d-8406-221f34ed9807" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_0b1305ee-ee0f-482e-8a6a-105bef196f2a" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour_4d9eebad-16c9-479d-8406-221f34ed9807" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo_ee7abdc0-a644-4cf6-8d9f-754ed052e11a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_0b1305ee-ee0f-482e-8a6a-105bef196f2a" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo_ee7abdc0-a644-4cf6-8d9f-754ed052e11a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalRemainderOfFiscalYear_b8c23ba6-4677-4d92-bbca-03209b8fdb70" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalRemainderOfFiscalYear"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_0b1305ee-ee0f-482e-8a6a-105bef196f2a" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalRemainderOfFiscalYear_b8c23ba6-4677-4d92-bbca-03209b8fdb70" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree_971d1072-fa8c-42bb-bd0b-6e9a402c0a22" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_0b1305ee-ee0f-482e-8a6a-105bef196f2a" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree_971d1072-fa8c-42bb-bd0b-6e9a402c0a22" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/LeasesComponentsofLeaseExpenseDetails" xlink:type="simple" xlink:href="psix-20240630.xsd#LeasesComponentsofLeaseExpenseDetails"/>
  <link:calculationLink xlink:role="http://powersint.com/role/LeasesComponentsofLeaseExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_psix_LeaseCostExcludingSubleaseIncome_7e00db00-9eaa-432c-b6f5-8334ac7d4410" xlink:href="psix-20240630.xsd#psix_LeaseCostExcludingSubleaseIncome"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseInterestExpense_d6962d13-d06f-42bd-bb87-40b029c51dca" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinanceLeaseInterestExpense"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_psix_LeaseCostExcludingSubleaseIncome_7e00db00-9eaa-432c-b6f5-8334ac7d4410" xlink:to="loc_us-gaap_FinanceLeaseInterestExpense_d6962d13-d06f-42bd-bb87-40b029c51dca" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermLeaseCost_c55d3d50-04b3-42df-8b19-2d0902f2f324" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShortTermLeaseCost"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_psix_LeaseCostExcludingSubleaseIncome_7e00db00-9eaa-432c-b6f5-8334ac7d4410" xlink:to="loc_us-gaap_ShortTermLeaseCost_c55d3d50-04b3-42df-8b19-2d0902f2f324" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubleaseIncome_dfb1a434-cfca-44c0-8f3b-2d2f6e6f60fa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubleaseIncome"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_psix_LeaseCostExcludingSubleaseIncome_7e00db00-9eaa-432c-b6f5-8334ac7d4410" xlink:to="loc_us-gaap_SubleaseIncome_dfb1a434-cfca-44c0-8f3b-2d2f6e6f60fa" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableLeaseCost_310c0c1a-0edf-4109-be28-26031aeaa5f8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableLeaseCost"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_psix_LeaseCostExcludingSubleaseIncome_7e00db00-9eaa-432c-b6f5-8334ac7d4410" xlink:to="loc_us-gaap_VariableLeaseCost_310c0c1a-0edf-4109-be28-26031aeaa5f8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseCost_f05f72b1-2e15-4346-bf2d-53ef3fc32260" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLeaseCost"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_psix_LeaseCostExcludingSubleaseIncome_7e00db00-9eaa-432c-b6f5-8334ac7d4410" xlink:to="loc_us-gaap_OperatingLeaseCost_f05f72b1-2e15-4346-bf2d-53ef3fc32260" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAssetAmortization_d18a71c7-be95-4905-88ed-55351805fa6f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinanceLeaseRightOfUseAssetAmortization"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_psix_LeaseCostExcludingSubleaseIncome_7e00db00-9eaa-432c-b6f5-8334ac7d4410" xlink:to="loc_us-gaap_FinanceLeaseRightOfUseAssetAmortization_d18a71c7-be95-4905-88ed-55351805fa6f" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/LeasesSupplementalBalanceSheetInformationDetails" xlink:type="simple" xlink:href="psix-20240630.xsd#LeasesSupplementalBalanceSheetInformationDetails"/>
  <link:calculationLink xlink:role="http://powersint.com/role/LeasesSupplementalBalanceSheetInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_ccaac074-e388-4e97-8804-ed8d58001e63" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLeaseLiability"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_2c97769a-e20f-4bf9-869c-49b733f586c8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_ccaac074-e388-4e97-8804-ed8d58001e63" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_2c97769a-e20f-4bf9-869c-49b733f586c8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_de2803a0-f1f6-4a5a-b840-bb816330dcaa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_ccaac074-e388-4e97-8804-ed8d58001e63" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_de2803a0-f1f6-4a5a-b840-bb816330dcaa" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiability_1a3c6561-2b70-4e73-a75e-e2c133321641" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinanceLeaseLiability"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityCurrent_cfb4453f-a25b-4405-8bc9-5381b51cf39b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_1a3c6561-2b70-4e73-a75e-e2c133321641" xlink:to="loc_us-gaap_FinanceLeaseLiabilityCurrent_cfb4453f-a25b-4405-8bc9-5381b51cf39b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityNoncurrent_0387f673-19b4-425d-ad4e-2649892b0ef5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_1a3c6561-2b70-4e73-a75e-e2c133321641" xlink:to="loc_us-gaap_FinanceLeaseLiabilityNoncurrent_0387f673-19b4-425d-ad4e-2649892b0ef5" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/LeasesMaturityAnalysisofLeaseLiabilitiesDetails" xlink:type="simple" xlink:href="psix-20240630.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_284743b4-3a38-4f00-86a9-2def7730b88f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount_d1fa412a-5f27-427d-8af3-294b07b6b3ab" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_284743b4-3a38-4f00-86a9-2def7730b88f" xlink:to="loc_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount_d1fa412a-5f27-427d-8af3-294b07b6b3ab" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiability_75d95e4d-e7c2-4e03-9ffa-8ace444386f9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_284743b4-3a38-4f00-86a9-2def7730b88f" xlink:to="loc_us-gaap_FinanceLeaseLiability_75d95e4d-e7c2-4e03-9ffa-8ace444386f9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_76166863-f461-4d56-a02a-ed3538b63910" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_06d9a403-b918-4ec4-85fe-b47d76d5c34c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_76166863-f461-4d56-a02a-ed3538b63910" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_06d9a403-b918-4ec4-85fe-b47d76d5c34c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_7133dad3-282a-43ba-bc00-ccc40cc08b1f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_76166863-f461-4d56-a02a-ed3538b63910" xlink:to="loc_us-gaap_OperatingLeaseLiability_7133dad3-282a-43ba-bc00-ccc40cc08b1f" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/LeasesMaturityAnalysisofLeaseLiabilitiesDetails_1" xlink:type="simple" xlink:href="psix-20240630.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_a5b7dc9b-8f3c-411e-bd8c-db4399bd8280" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsRemainderOfFiscalYear_c9d67ef5-481c-48cd-b4d1-f02a745ede66" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinanceLeaseLiabilityPaymentsRemainderOfFiscalYear"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_a5b7dc9b-8f3c-411e-bd8c-db4399bd8280" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsRemainderOfFiscalYear_c9d67ef5-481c-48cd-b4d1-f02a745ede66" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive_46f5308e-a91b-454c-a3a5-de4661ea13d4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_a5b7dc9b-8f3c-411e-bd8c-db4399bd8280" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive_46f5308e-a91b-454c-a3a5-de4661ea13d4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths_f31554ea-0afe-44ef-ba7a-42e3d3af0af2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_a5b7dc9b-8f3c-411e-bd8c-db4399bd8280" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths_f31554ea-0afe-44ef-ba7a-42e3d3af0af2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive_fb9f7183-8df5-44ab-9159-197f59e72fb8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_a5b7dc9b-8f3c-411e-bd8c-db4399bd8280" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive_fb9f7183-8df5-44ab-9159-197f59e72fb8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree_7cf1c37a-8e3c-41b1-a4e4-176aa1377a06" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_a5b7dc9b-8f3c-411e-bd8c-db4399bd8280" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree_7cf1c37a-8e3c-41b1-a4e4-176aa1377a06" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo_773dd225-8944-4262-ad31-675ba69850dc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_a5b7dc9b-8f3c-411e-bd8c-db4399bd8280" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo_773dd225-8944-4262-ad31-675ba69850dc" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour_543d2989-0c11-4745-ba4d-3a935ee6f703" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_a5b7dc9b-8f3c-411e-bd8c-db4399bd8280" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour_543d2989-0c11-4745-ba4d-3a935ee6f703" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_9e1b98c8-72ad-4d72-9e57-e664bef6a86c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_3f2fb108-d521-40bb-8954-470318a03305" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_9e1b98c8-72ad-4d72-9e57-e664bef6a86c" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_3f2fb108-d521-40bb-8954-470318a03305" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_8ba41bc3-bdda-4948-a2f6-1e972d585974" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_9e1b98c8-72ad-4d72-9e57-e664bef6a86c" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_8ba41bc3-bdda-4948-a2f6-1e972d585974" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear_c076878d-73d9-4c8d-8bb3-6199cf9c4b21" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_9e1b98c8-72ad-4d72-9e57-e664bef6a86c" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear_c076878d-73d9-4c8d-8bb3-6199cf9c4b21" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_0064f673-7d83-45c0-816e-012ec90c870d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_9e1b98c8-72ad-4d72-9e57-e664bef6a86c" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_0064f673-7d83-45c0-816e-012ec90c870d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_0b1cf8f7-12fd-4b8b-a7b4-f9a456318fcf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_9e1b98c8-72ad-4d72-9e57-e664bef6a86c" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_0b1cf8f7-12fd-4b8b-a7b4-f9a456318fcf" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_aa5d431e-1438-4305-bb15-bd8f66eea75a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_9e1b98c8-72ad-4d72-9e57-e664bef6a86c" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_aa5d431e-1438-4305-bb15-bd8f66eea75a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_9ecfaf2f-a22e-4df4-a4b4-648b74c4c327" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_9e1b98c8-72ad-4d72-9e57-e664bef6a86c" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_9ecfaf2f-a22e-4df4-a4b4-648b74c4c327" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://powersint.com/role/EarningsPerShareDetails" xlink:type="simple" xlink:href="psix-20240630.xsd#EarningsPerShareDetails"/>
  <link:calculationLink xlink:role="http://powersint.com/role/EarningsPerShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_76d46200-6d5e-4a50-8c4a-8b6b8e77c783" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_2db6f75f-1e07-4290-871c-a2f5e1cbd598" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_76d46200-6d5e-4a50-8c4a-8b6b8e77c783" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_2db6f75f-1e07-4290-871c-a2f5e1cbd598" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment_0a3828bf-2dbe-487f-af3e-6b654678e2d3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_76d46200-6d5e-4a50-8c4a-8b6b8e77c783" xlink:to="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment_0a3828bf-2dbe-487f-af3e-6b654678e2d3" xlink:type="arc"/>
  </link:calculationLink>
</link:linkbase>
