-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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<SEC-DOCUMENT>0000908255-08-000048.txt : 20080502
<SEC-HEADER>0000908255-08-000048.hdr.sgml : 20080502
<ACCEPTANCE-DATETIME>20080502120437
ACCESSION NUMBER:		0000908255-08-000048
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20080502
FILED AS OF DATE:		20080502
DATE AS OF CHANGE:		20080502

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			BORGWARNER INC
		CENTRAL INDEX KEY:			0000908255
		STANDARD INDUSTRIAL CLASSIFICATION:	MOTOR VEHICLE PARTS & ACCESSORIES [3714]
		IRS NUMBER:				133404508
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		3850 HAMLIN RD.
		CITY:			AUBURN HILLS
		STATE:			MI
		ZIP:			48326
		BUSINESS PHONE:		2487549200

	MAIL ADDRESS:	
		STREET 1:		3850 HAMLIN RD.
		CITY:			AUBURN HILLS
		STATE:			MI
		ZIP:			48326

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	BORG WARNER AUTOMOTIVE INC
		DATE OF NAME CHANGE:	19930628

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			NOVAK ERNEST J JR
		CENTRAL INDEX KEY:			0001255472

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-12162
		FILM NUMBER:		08797555

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		(330)666-3751

	MAIL ADDRESS:	
		STREET 1:		3550 WEST MARKET STREET
		CITY:			AKRON
		STATE:			OH
		ZIP:			44333
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-05-02</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000908255</issuerCik>
        <issuerName>BORGWARNER INC</issuerName>
        <issuerTradingSymbol>bwa</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001255472</rptOwnerCik>
            <rptOwnerName>NOVAK ERNEST J JR</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>3550 WEST MARKET STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>AKRON</rptOwnerCity>
            <rptOwnerState>OH</rptOwnerState>
            <rptOwnerZipCode>44333</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>common stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-04-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1252</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>13356</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <ownerSignature>
        <signatureName>John J. Gasparovic as attorney-in-fact for Ernest J. Novak Jr.</signatureName>
        <signatureDate>2008-05-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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