E36 M3 S50 vs S52 vs Euro S50B32 — which is the real M3 engine?

I have an E36 M3 with the Euro S50B32. It is an absolutely incredible engine. The individual throttle bodies give it a response that no single-throttle-body engine can match. The sound at 7000rpm with an aftermarket exhaust is addictive.

The S50B32 makes great power for its displacement — 321hp from 3.2L naturally aspirated in 1996 was remarkable. With a proper tune, headers, and intake, you can see 340-350hp at the wheels.

The downside is parts cost. S50 specific parts like the ITB assembly, VANOS unit, and camshafts are expensive and getting harder to find. Budget accordingly.

Important note on the S50B30 and S50B32 — both have VANOS systems that need attention. The single VANOS on the S50B30 is simpler but still fails. The double VANOS on the S50B32 is more complex and the seals degrade over time, causing rough idle and power loss.

Beisan Systems makes excellent VANOS rebuild kits for both engines. Budget about 200 EUR for the kit and a few hours of work. It is a must-do maintenance item on any S50 engine.