[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]

Re: S4 20v vs S2 10v

--------------------------- Begin X.400 Bodypart 1 --------------------------
  ========== On Mon, 6 Feb 1995 - quattro-owner wrote: ==========

--------------------------- Begin X.400 Bodypart 2 --------------------------
> Re:  The center coils:  my guess is this is a vital component when
running > hiboost with hi compression, not so key when using the low comp

my understanding is that the 9.3 compression on the S4 is for
off-boost response.. once the turbo spools up, CR is really quite a
meaningless number, because 2 bars of boost is 2 bars of boost,
regardless of what the geometric dimensions of the engine are.  i.e. 2
bars in a 9.3 compression engine is equally likely to detonate as 2
bars in a 7.8 engine, all other things being equal.. no?

NO! Think of it as boost pressure x mechanical compression ratio =
effective compression ratio

excess compression/cylinder pressure = detonation = $$$

However, the high(er) mechanical compression ratio is to improve off-boost

- -glen


----------------------------- End X.400 Bodyparts ----------------------------