by Dave Koehler


I'm building a 400 sbc for street/strip use. I'd like to run 11-1 compression. 91 octane pump fuel won't cut it here, so I'd like to spike it with 110 leaded race gas. How well does octane improve as leaded race fuel is added? I've heard small amounts help considerably and it is a case of diminishing returns as the percentage continues to increase. What do you think?

John McCarthy


I have never had a reason to mix pump gas so the answer is that I do not know. I do think that if you have a true 11:1 compression
that you should purchase the right fuel the first time. It would seem to me that mixing pump gas based on hearsay might cost more than purchasing the right fuel or using the 110 to begin with.

I recommend giving Torco or VP a call and see what they recommend.

Have a safe race,

Dave Koehler

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