Hot Rod Forum : Hotrodders Bulletin Board - View Single Post - compression ratio vs. pounds per square inch.
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Old 03-16-2013, 05:00 AM
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When considering CR to boost pressure, the limit for 93 octane pump gas is 12:1 effective CR. Anything over 12:1 effective CR will risk catastrophic detonation.

Static CR.................8:1
Boost pressure ....... 8 PSI
Effective CR.............12:1

Experience has shown that an engine will make more power from low CR - high boost than from a high CR - low boost. Engines will differ in their tolerance to detonation so this rule is not hard and fast but it is a good place to start. It is easier to change boost than it is to change compression ratio.
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