This is topic higest compression ratio for 91 oactane in forum Tech Talk at Northern California Ford Owners  .


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Posted by 79 cobra (Member # 10137) on :
 
What the highest you think I can get away with 91 oactane plan on buying new rods and pistons but want the higest compression with out denoting was thinking either 11.1 - 11.8

[ 2014-04-15, 06:14 AM: Message edited by: 79 cobra ]
 
Posted by 5.0 LsX (Member # 10017) on :
 
what motor? what heads? what cam?
 
Posted by Tom Renzo (Member # 13165) on :
 
Depends on the CAM!!!!
 
Posted by 4IDFOX (Member # 9921) on :
 
quote:
Originally posted by Tom Renzo:
Depends on the CAM!!!!
What Tom said.

Dynamic (cranking) compression is what matters. And that is controlled by the cam timing events. You could have a 12:1 motor that will run on 91 and a 10:1 motor that will not because of the cam timing events.

The motor in my road race car is a flat top piston 306 wit 58cc heads. That is about a 10:1 motor. But with the custom cam I run I have 196# of compression from a 10:1 motor.

[ 2014-04-15, 08:50 PM: Message edited by: 4IDFOX ]
 
Posted by 79 cobra (Member # 10137) on :
 
Gonna be a 5.4l with c heads and comp stage 3 nitous cams and heads are 52 cc
 
Posted by Tom Renzo (Member # 13165) on :
 
Need specks on cam.
 
Posted by Vndcatr (Member # 2343) on :
 
quote:
Originally posted by 79 cobra:
Gonna be a 5.4l with c heads and comp stage 3 nitous cams and heads are 52 cc
Quick question on your build setup.. I see you have the 52cc 03/04 heads, Which piston are you using?

[ 2014-04-16, 05:22 PM: Message edited by: Vndcatr ]
 
Posted by 79 cobra (Member # 10137) on :
 
Going with manley pistons and h beam rods
 
Posted by 79 cobra (Member # 10137) on :
 
Got a deal on a 98 cobra shortblock going to buy rods and pistons but still need to know if 11.1 will work going to be a c head motor with stock cams

Thanks ,
Brett
 
Posted by Tom Renzo (Member # 13165) on :
 
Depends on the cam!!
 
Posted by 79 cobra (Member # 10137) on :
 
Going to use the stock cams from my mach 1
 
Posted by Fostang (Member # 3752) on :
 
http://cochise.uia.net/pkelley2/DynamicCR.html

Educate yourself

Heres a decent calculator to assist you

http://www.projectpontiac.com/ppsite15/compression-ratio-calculator

[ 2014-04-28, 10:41 AM: Message edited by: Fostang ]
 




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