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View Full Version : Compression ratio...


WVSNS&
09-15-2006, 04:10 PM
On my 01. The head gaskets were replaced under warranty at 43k. Just turned 56k. Was considering going fi. If the old compression was 9,85 to 1 what is the new ratio with twenty five thousandths? Does this matter when adding the blower?

john

97BlackSnake
09-17-2006, 11:30 PM
What is twenty five thousandths? The head is closer to the block?

WVSNS&
09-18-2006, 08:00 AM
The machine shop shaved a little bit off the heads to make sure the surface was flat or flatter before the new head gaskets went on. The combustion chambers I understand are slightly smaller. Or the head where the valves are is closer to the fire. I am just curious.


john

BillHyco
09-19-2006, 12:10 AM
sounds like a typical resurface or planing which is the norm when rebuilding an engine or replacing a head gasket. Perfect, flat surface ensures proper gasket seal to prevent leaks of any type. If the head is only resufaced, that micro amount of metal removed unfortanetely isn't going to do much for your compression if that is what you are asking. If it did happen to raise it any at all, your not going to notice any difference anywhere. Atleast not from my experiance. If I am wrong certainly someone will correct me I hope.

Bill

WVSNS&
09-19-2006, 08:25 AM
I haven't noticed any hp gains. Many are saying because the compression is so high anyway that a blower may not give tha gains as if I started w/a lower compression. I am not opposed to staying na but want to get some power and still have the ability to drive it daily.



john

blk04cobra1
09-19-2006, 09:09 AM
I haven't noticed any hp gains. Many are saying because the compression is so high anyway that a blower may not give tha gains as if I started w/a lower compression. I am not opposed to staying na but want to get some power and still have the ability to drive it daily.
john
I think it just depends on how much power you are looking for. Just bolting up a supercharger will still net you about 115+hp, no matter what...9.8:1 is still fairly low in the compression range, even though stock '03 cobra's came in at 8.5:1, but that was only b/c of the factory supercharger. On another note, you could always up the compression and through a big shot of nitrous on it :thumbsup: