If I go from 10:1 to 12.5:1 how much hp would I gain? Right now the motor dynoed 588. The heads should support 660hp. What do you guys think? Thanks Rick
It's hard to tell how much you will gain, but your whole power curve will move up, not just the peak!
Hey Rick, How are you? Stewy tells me you two squared off in a match race in Malta this summer!! Sounds like you guys had a great race. The first question would be how are you achieving the higher compression? Pistons, decking block, milling heads, etc. it will make a difference. If you deck the block, mill the cylinder heads or change pistons without knowing how the cylinder heads were set-up, you could gain the extra compression ratio while at the same time be killing the airflow in your cylinder heads. Give me a call sometime Rich and I would be happy to share some more of what I stumbled onto during my IHRA crate motor build-up! 208-691-6394. Jody
The motor has TA stage1 SE heads done by AMP. The block showed some wear between the cylinders so the block was decked some, the pistons are now about .005 above the block. I off set that with Cometic gaskets. Compression is 10.3 or so now. To get the extra compression I would go with flat top pistons. It is an AMP 470 motor. I will be pulling the motor out to check things over this winter. I might add the pistons then. I am running methonal with a Flying toilet so the more compression the better. Jody, Stew and I never got a chance to square off. He runs just a little quicker than me, always been that way even back in the 80's. If I add some more ponies I can claim "Montana's Fastest Buick" HAHAHAHA Thanks Rick
I agree. Car Craft did a test on a Mopar 440. From 8 to all the way to 11 to 1. About 4% per point of compression. The 440 lost 60HP at 8 to 1.
Sorry, I was in a hurry that day. I should have said "adaquate airflow capablity". Bumping the compression on a race motor that is cylinder head limited, will improve the torque, but you won't see it so much in the HP. JW
The heads have an estimated hp potential of 659. I would say all the parts are "matching components". Thanks Rick
Rick, I would expect a little more gain from compression when burning alky. I'm a little surprised that it ran that well with just 10:1 compression. I've read that it needs minimum 11:1 to be viable, but you seem to have proven that wrong:beers2:
If my memory serves me correctly, as the compression ratio increases, the gains from increases diminish. For example increasing from 8:1 to 9:1 has considerably more power increase than increasing from 11:1 to 12:1. Engine builders correct me if I am wrong on this.
Considering good heads are being used..... If the 8:1 engine has a deck height of, say .050 and the 10:1 has a zero deck, or close, the HP gain will be considerable. From that point on (with zero deck) will be a little less, but beneficial in keeping up with the use of bigger cams.
