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Maximum Safe CR for HP 500 on 89 pump

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Maximum Safe CR for HP 500 on 89 pump

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Old 03-14-2010, 10:02 PM
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Default Maximum Safe CR for HP 500 on 89 pump

When rebuilding a HP500 would there be anything to be gained by bumping compression ratio up a bit from 8.75 to 9.25? What would be the max safe CR for stock HP500 on 89 octane and what if any timing adjustments might need to be done? It seems that there is some extra power to be had even with stock heads if one is willing to run 89 octane.

To further this thought what about max safe CR for same engine but using 93 octane?

HP 500 with Holley Carb and Blue Single Plane intake.

Last edited by BadDog; 03-14-2010 at 10:30 PM.
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Old 03-14-2010, 10:57 PM
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I would say about 9.0 on 89 and stay under 9.5 for 93.
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Old 03-14-2010, 11:08 PM
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what about with aluminum heads?
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