Volume IX, Issue 6, Page 98

FUELforTHOUGHT

by Dave Koehler
06/08/07

I'm using 98% ethonal in my face car and so far like it.The compression ratio is 11 to 1. I'm wondering if a higher ratio would improve motor performance?

Don
Oregon

Don,

Good for you. While I am sure you have heard of astronomical compression ratio numbers, I like a max of 13.5 compression (real, not guessed at) on a normally aspirated engine. What's the extra compression worth?  5-20 horses depending on your base combination. If you are primarily bracket racing I would leave it alone as the higher the compression and the higher the HP the touchier the tune up gets regardless of the fuel used. If you make the change be aware that piston to valve clearance and dome to head clearance will need to be checked as well as a possible re-balance of the crank.

Have a safe race,

Dave Koehler
www.koehlerinjection.com

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