1984 M88/3. With a 10.5:1 compression ratio and a single-row timing chain, it is identical to the one found in Euro-spec E28 M5 sedans. Power is rated at 286 hp (DIN) at 6,500 rpm with 251 lb./ft. of torque at 4,500 rpm. The M88 can be identified by the inscription on its cam cover: the propeller Roundel plus the words “BMW” or “M Power”.

The 1986 S38 is the “clean” version of the engine, introduced for North America but later offered in other markets as well. It utilizes a duplex (double-row) timing chain and lower 9.8:1 compression designed to work with catalytic converters. This reduced the horsepower to 256 hp (SAE) or 260 hp (DIN) at 6,500 rpm and torque to 243 lb./ft. at 4,500 rpm. The S38 has the inscription “BMW M Power” on its cam cover but no Roundel.