Comp Ratio ?
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Posting Guru
Joined: Dec 2000
Posts: 1,686
Likes: 1
From: Racine WI
Comp Ratio ?
How will my compression ratio be determined in my 390 ? strictly by the piston I use ? or are there different cc heads that add to the eqaution ?
Higher comp ratio makes more power right ? But I want to run on pump gas so I'm weary of anything higher than 9.5:1
Opinions and comments appreciated
Higher comp ratio makes more power right ? But I want to run on pump gas so I'm weary of anything higher than 9.5:1
Opinions and comments appreciated
Post Fiend
Joined: Sep 2000
Posts: 8,238
Likes: 3
From: Oregon
Comp Ratio ?
Yes, the cc of the combusion chamber drastically effects compression...the smaller the chamber the higher the compression. I think you would be fine at 10:5:1 if you wanted to run premium pump gas, but you are definitly safe at 9:5:1.
Elder User
Joined: Aug 2001
Posts: 962
Likes: 2
From: Collierville, TN
Comp Ratio ?
Piston height and dish or dome will affect CR, as will gasket thickness and combustion chamber volume. Basically, anything that affects the amount of space left above the top of the piston at TDC will impact CR. That's why there may be a range of compression ratios listed for replacement pistons.
