The BMW S38 is a straight-6 DOHC piston engine which replaced the M88 and was produced from 1986-1996. It is based on the M88/3 engine.[1] This engine is similar to the M30, but has a 24-valve cylinder head, duplex timing chain, dual overhead cam layout and shim and bucket style valvetrain.[citation needed] In addition to the top end revisions, the S38 also had six individual throttle bodies and intake trumpets fed by a cast aluminum intake plenum. For the S38B36 displacement was enlarged from 3453 to 3535 cc,[3] achieved by increasing the stroke from 84mm to 86mm[1] by using a longer forged steel crankshaft.[citation needed] Different camshafts were also used and the compression ratio was increased to 10:1.[citation needed] A variable-length inlet manifold was used claimed to improve torque output,[1] equal length stainless steel exhaust headers remains.[4] The fuel injection system was Bosch Motronic.
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