This is topic Compression Ratio Question????? in forum Tech Talk at Northern California Ford Owners  .


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Posted by 88bird (Member # 1424) on :
 
With aluminum heads, whats the highest ratio I should run on the street??? 331, w/ afr's and custom ground cam...
 

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Posted by AaronC (Member # 86) on :
 
Your typical 331 with SRP -5cc valve relief piston and 58cc AFR head will give around 10.5 compression which is good. A 347 with the same piston and 56cc AFR will give 11.0. 10.5-11.0 is pretty common on street/strip strokers these days running 91pump gas. Camara90 ran 11.1 on 91 without any problems

[ December 09, 2003, 05:31 PM: Message edited by: AaronC ]
 

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Posted by Bounty Hunter (Member # 1422) on :
 
if you want to stick with pump gas I would go with a 10:1 motor
 

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Posted by Blue Oval (Member # 2548) on :
 
Ive run 10.5 and its a PERFECT street compression.
it runs on pump gas NO PROBLEM
Id go 10.5.

[ December 09, 2003, 05:03 PM: Message edited by: Blue Oval ]
 

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Posted by Yellow94GT (Member # 431) on :
 
My 11:1 motor runs fine on 91 octane
 

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Posted by mustanggt5091 (Member # 444) on :
 
so does my 11:1
 

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Posted by ON N2O (Member # 2067) on :
 
by 12:1 91 octane 383chevy engine ran great on pump gas, i even shifted her at 9800rpm
 

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Posted by BlueOvalRacing (Member # 1531) on :
 
ttt
 

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Posted by st5150 (Member # 51) on :
 
another vote for 10.X:1
 

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Posted by z ya (Member # 1327) on :
 
If you plan to run 10.5 to 1 and above you better have a fairly stout cam in there or your dynamic comp ratio will be too high and it will ping. If you have a fairly stout cam in it ...it will help bleed of cylinder pressure so that pump 91 can be used.
 

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