compression ratio advantages/disadvantages with turbo...

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Jun 29, 2005 | 10:48 AM

will62085

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compression ratio advantages/disadvantages with turbo...

so, we all know the obvious advatages and disadvantages to having too high or too low compression with a FI setup...but what are the limits? for me personally i would like to know how low should it be for max power? i was goin with 8.4:1 but now im thinking lower...

Jun 29, 2005 | 10:54 AM

777

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I wouldn't think you would want to go to much past 8.5:1. I'd say typical is going to be around 9:1.

Jun 29, 2005 | 10:56 AM

nitrorocket

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Duttweiler told me that on a 347" motor, any lower then 8:1 would not be good. That is what I chose.

Jun 29, 2005 | 11:23 AM

Wet 1

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Why go so low? It's hard to keep the heads down on an LSx engine above 16 psi anyway and you can get there with 9:1... why go lower if you can't add more boost???

Jun 29, 2005 | 11:46 AM

Zombie

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Quote:

Originally Posted by Wet 1

Why go so low? It's hard to keep the heads down on an LSx engine above 16 psi anyway and you can get there with 9:1... why go lower if you can't add more boost???

How much boost you run has absolutely nothing to do with lifting the heads, unless you figure out a way to run over 1000 psi of boost.

Last edited by Zombie; Jun 29, 2005 at 12:00 PM.

Jun 29, 2005 | 11:51 AM

Wet 1

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So you are suggesting that LSx owners could run 7.5:1 and 30+ psi with no detonation and not lift the heads???

Jun 29, 2005 | 11:53 AM

99SS-T

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Aye Parish is pushin 22 psi i think and he has no issues. The reason heads lift is detonation. Causes like 10x the stress that regular stroke causes. 9.1 does seem to be pretty good. If you want to avoid having to use meth you could make the CR lower liek 8.5 but ya are gonna have to move quite a bit more air to make the same power. Not that that is a big problem but it takes away from the max you can make with that same turbo. I personally am gonan go 9.1 when i go forged as it seems to be a good middle ground. Another thing of 8.5 is when you are puttin around or going somewhere that ya dont need 900 hp you it is gonna feel like a dog unless it is a big stroker. Well GL man

John