M50 / M52 / S50(US)

The BMW M50 is a straight-6 DOHC piston engine which replaced the BMW M20 and was produced from 1990 to 1996. Compared with its M20 predecessor, the M50 features twin camshafts and 4 valves per cylinder. The M50 uses an iron block with an alloy head.[1] In September 1992, the M50 was upgraded to the M50TU ("technical update"), which added variable valve timing (called VANOS by BMW).[2] The E36 M3 was powered by the S50 engine series, which is based on the M50.