BMW S38

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. 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. 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.

The S38B35 was based on the M88/3, but with changes including a dual-row timing chain, camshaft, compression ratio lowered to 9.8:1 and fitted with a catalytic converter.

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For the S38B36 displacement was enlarged from 3453 to 3535 cc, achieved by increasing the stroke from 84mm to 86mm by using a longer forged steel crankshaft. Different camshafts were also used and the compression ratio was increased to 10:1. A variable-length inlet manifold was used claimed to improve torque output, equal length stainless steel exhaust headers remains. The fuel injection system was Bosch Motronic.

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In 1992, BMW further enlarged the S38 engine to 3795 cc, with power climbing to 250 kW (340 hp) and torque increasing to 400 N·m (300 lb·ft). Coil-on-plug ignition replaced the traditional distributor which was used on previous S38 engines and the Bosch Motronic 3.3 fuel injection system was used. Other upgrades include:

This engine was used in the E34 M5 until finished production in 1996.

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