Originally Posted by B3422W5
Originally Posted by 451Guy
I realize that this is a bit of a loaded question but from your experience how much power will a motor lose from reducing the compression given that you have a suitable cam in both engines, given every thing else in the engine is the same.

Compression from 13.5 to one to 10.5 or 11.00 to one Race gas to premium pump gas..

Thanks


I have read in many different places that a point in compression is 2-3%. Once you get to a high compression, its a case of diminishing returns.
You said you were going to swap to a cam more suitable to the new compression.
My guess 30-40 horsepower just from compression.
iagree I've seen testing done on a SB Mopar bracket motor that lost 30 HP by reducing the compression ratio from 12.5 to 10.6 or so so they could run pump swill with no other changes(timing or jetting)that made a 560 HP motor make 530 HP shruggy
They should have optimized the timing, jetting and spark plug heat range with the lower compression ratio on the engine dyno instead of doing it later at the track twocents Those changes made it run faster than it had before, that racer is now a big advocate of low compression race motors confused shruggy

Last edited by Cab_Burge; 10/21/20 06:39 PM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)