The BMW S38 is a straight-6 DOHC petrol engine which replaced the M88 and was produced from 1984–1995.

[1][2] The S38 was originally produced for North America as an equivalent to the M88 with slightly lower power output.

[3] Compared to the M88/3, the S38 has a lower compression ratio (9.8:1), simplified exhaust manifold, catalytic converter, dual-row timing chain and a shorter camshaft duration.

[8] Other changes included revised camshafts, compression ratio increasing to 10:1, a variable-length inlet manifold (to improve low-rev torque),[3] equal length stainless steel exhaust headers[9] a hotwire mass airflow sensor (MAF) and Bosch Motronic engine management.

Other changes included the compression ratio increasing to 10.5:1, a dual-mass flywheel, an exhaust manifold made of Inconel, larger intake and exhaust valves, lighter pistons, and the throttle bodies increasing by 4 mm (0.16 in) to 50 mm (2.0 in).