Originally Posted by Holander
Actually at least S50, S52 and S54 engines are pretty different than M50-based M52 and M54. S-series didnīt share same block, crank, pistons, head, intake manifold etc. You can check it in Realoem.com.
There might be a different part number, doesn't mean it's a totally different design though... They where based on the std. engines.
I guess you can do the exact same thing on Realoem.com with the next gen M3 engine. Plenty of different part numbers that separates it from the engine it is based on.