Originally Posted by Uli_HH
If you use the N55 block to develop the M3/M4 engine, its clear that the stroke was greater than the bore, an layout that make it almost impossible to combine high rpm and high pressure turbos, simply because the resulting forces are going too high ... only with an square cylinder layout it was possible to combine high pressure turbos with 8.000rpm.
Ohhhh, thats what you mean by square cylinder. I just call those short stroke, big bore engines aka 'racing engines'. lol I see, so what you're saying is only the stroke length can be increased but not the bore due to thickness limitations inbetween the cylinders. But what if the distance between the cylinder walls on the updated S55 are much thicker allowing for a bore out? I wouldn't assume it would be the same as the N55.