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-   -   Maximum Safe CR for HP 500 on 89 pump (https://www.offshoreonly.com/forums/general-q/226349-maximum-safe-cr-hp-500-89-pump.html)

BadDog 03-14-2010 10:02 PM

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.

Griff 03-14-2010 10:57 PM

I would say about 9.0 on 89 and stay under 9.5 for 93.

endeavour32 03-14-2010 11:08 PM

what about with aluminum heads?


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