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opinions wanted compression ratio


Dave1647545494

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aluminum cylinder head with a good quench area N/A 351w efi stock timing middle of the road street cam (under .600 lift under 300 deg of duration)

 

11.5:1 going to be too much for 94 octane

 

 

I ran that compression( or higher :) ) on my iron head buicks, but with much bigger cams. never caused me any trouble so it seems doable,but fords are not buicks and I'm not sure

 

 

thanks

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Is this advertised compression dave?

 

is the block decked at all?

 

 

advertised compression with my head volume 60cc

 

the block is currently an untouched low mile low compression truck block

 

ps I will not have my car at work for a couple days ( left the window down and the damn seat got all soaked)

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too much

 

10.5 is really ideal for a 93 octane street motor, in my experience (alum heads)

9.5 for iron heads

 

if you're perfectly tuned, and EFI helps...11.0 is doable

 

11.5 seems like you'd be asking for detonation

or having to mess with timing so much that you'd be out of the power range it was built for

 

i have no direct experience with Fords though...

 

a good quenching chamber and the cam designed for the high compression can really help, ask crower for one that bleeds off the pressure a little maybe

 

but i typically build motors that have a little room for my error....i'd be afraid of that being a monster to tune

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it will depend on the cam. Ive had 12.5 to 1 sbf's running 93-94 octane all day.

 

thers always octane booster aswell.

 

and like iroc said, it depends alot on how far the piston lands in the hole.

 

Ive seen some as bad as .019 down the hole. making a 11.5 to 1 piston closer 10.9 to 1.

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