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Re: S4 20v vs S2 10v
- To: quattro@swiss.ans.net (Non Receipt Notification Requested) (IPM Return Requested)
- Subject: Re: S4 20v vs S2 10v
- From: glen.powell@smc.com
- Date: 07 Feb 1995 08:30:24 -0500
- Autoforwarded: FALSE
- Importance: normal
- Message-Type: Multiple part
- P1-Content-Type: P2
- P1-Message-Id: US*ATTMAIL*SMCLAN;X400ATT Feb 07 08:30:24 1995
- P1-Recipient: quattro@swiss.ans.net
- Priority: normal
- Reply-To: quattro
- Sender: quattro-owner
- Ua-Content-Id: 243008070295
- X400-Trace: US*ATTMAIL*SMCLANarrival 07 Feb 1995 08:30:24 -0500action Relayed
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========== On Mon, 6 Feb 1995 - quattro-owner wrote: ==========
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> 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
motor.
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
performance.
- -glen
eliot
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