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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
Effective Compression on Boost

We see a lot of people experimenting with different static compression ratios and boost levels.

It is interesting to see what the effective compression ratio(ECR) is with different combination. Bellow is the something I saw in another post that displays this nicely.

By playing with a mix of base compression ratio, boost, cam timing, AFR and intake temperatures we try to do the dance around pre-detonation.

It is interesting that a stock 930 running .8 bar boost on a static CR of 7/1 is an ECR of about 10.7/1 against a 993 CR of 11/3.

Looks like it would be fun to build a 6/1 CR motor and run 1.4 bar of boost for a ECR of about 11/1. It also looks like a motor running.8 bar boost on 8/1 CR might be on the edge and in need of race fuel to run safely.

Can anyone help me better understand how some are running boost in the 20 lbs/inc and even 30's?

Old 04-07-2009, 02:05 PM
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