What is the highest compression ratio for 91 oct.
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From: Wichita, Ks.
What is the highest compression ratio for 91 oct. A general question. No knocking and other related problems, what would be the limits of 91 octane in terms of compression ratio, 11:1? 11.5:1 or 12:1?
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From: Ft. Lauderdale, FL, USA
Originally Posted by ss dave
A general question. No knocking and other related problems, what would be the limits of 91 octane in terms of compression ratio, 11:1? 11.5:1 or 12:1?
.
Originally Posted by ss dave
A general question. No knocking and other related problems, what would be the limits of 91 octane in terms of compression ratio, 11:1? 11.5:1 or 12:1?
11:1, but I'm sure you're going to get people contesting me on that.
It depends much less on static compression and more on Dynamic compression. You need to get your cam specs and plug them as well as your combustion chamber cc's piston valve reliefs(if applicable) etc into a DCR calculator and find out where you are at. I have heard anywhere from 8.5-8.7 is the max for 91 octane. I am shooting for something like 8.6 for my build.
Greatly depeneds on alititude. In Denver, 5200ish feet, I ran 12.5:1 on 91 without a single problem. Once the car went lower in altitude, higher octane gas was a must.
Keith
Keith
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