Originally Posted by alexus87
While the S54 was indeed an updated version of the S52 and was not based on the M54, the S52 you guys had in the US and the European S50 were both based on the M50 and were not bespoke engines. As such the S54 is just an updated version of an engine that was itself a performance version of a regular AG one.
Sorry! But NO ... you must define the word "based on" correctly !!!
All M3 engine until now which were based on AG engines only share the basic engine block layout with their AG counterparts ... really all other parts were bespoken part only developed for the S50s and the S54 (the special US M engines are an other story!).
if BMW today speaks in the case of the F8x about an "heavily" modified N55 as basis and you also know that only cost reduction were the reason to choose this engine alternative ... it seem clear that "this engine" must be the cheapest possible way to reach the needed ~450hp ... so "heavily modified" meens in my opinion:
- stronger engine block/crankcase by puting struts on the outside
- better/greater Turbos-system by using the TriTurbo of the N57S
- adding the newest VANOS availiable
- intelligent software
... plus some minor parts ... I think that would be all and I donīt define this as "heavily modified", its only an AG N55 with some better (newer) parts. If the M-GmbH would modify the N55 more heavily the cost would rise sharply and thats against all whats the BMW AG sought to achieve the BMW AG with its engine decision.