BMW S14

The BMW S14 is a DOHC four-cylinder petrol engine which was used in the E30 M3, E30 320iS, and E36 318i Super Touring. It is based on the BMW M10 block and what is essentially a shortened BMW S38 cylinder head. The direct successor to the S14 was the S42 based on the M42 engine. The S42 was a racing engine installed in the E36 320i for the German Super Tourenwagen Cup. There is no direct successor to the S14 for production BMWs, since the following generation of M3 is powered by the BMW S50 six-cylinder engine.

Two separate throttle bodies are used, each incorporating two throttle butterfly plates.

S14B20
This version was only sold in Portugal and Italy. It has a displacement reduced to 1990 cc by shortening the stroke to 72.6 mm.

Applications:
 * 1987-1990 E30 320iS (Italy and Portugal only)

S14B23
The E30 M3 was initially released with the 147 kW S14B23 engine. Versions equipped with a catalytic converter produced 143 kW and 230 Nm. In April 1989, the Ravaglia and Cecotto limited edition M3s were released with a 158 kW S14B23 that would in September, 1989 become the standard motor for the E30 M3.

Applications:
 * 1986-1991 E30 M3

S14B23 EVO2
This update of the S14B23 produced 162 kW, or 158 kW if equipped with a catalytic converter.

Applications:
 * 1988-1990 E30 M3

S14B25 EVO3
In 1989, the displacement was enlarged to 2467 cc and this engine produced 175 kW.

Applications:
 * 1989-1990 E30 M3