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Old 10-11-2019, 05:34 AM   #6
Patrick L.
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Join Date: May 2010
Location: Upstate NY and western Florida
Posts: 5,204
Default Re: Max Compression Ratio

Originally Posted by Pete View Post
The PRACTICAL limit is usually determined by the octane of the gas you run.
The design limit of the parts and the cooling system are way beyond what they can be stressed by raising the compression alone. I have run 10 to 1 in street model B flathead engines. 14 to 1 flathead model B on alcohol.

It was common for overhead valve conversion model B race engines in the old days to run 15 to 1 on alcohol. That was with babbit bearings.

WOW, learn something every day.
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