Compression ratio vs Porting

We just did some dyno testing on air flow increases versus horsepower increases. If you increase the compression ratio one point from 9.5 to 10.5 you will get approximately 3-4% increase. So a 300 HP engine would increase from 9-12 HP.

Theoretically if you increase the cylinder head flow on a race engine you could gain 2-2.25HP/CFM. But we found on the dyno, on a engine in the 400 HP range, if you change nothing but the cylinder head flow you will gain 1.25 HP/CFM. So, a 10 cfm increase would give you 12.5 horsepower increase. A novice, just cleaning up a port, could possibly get 10-20 cfm gain if you follow these instructions.

http://www.forabodiesonly.com/mopar/showthread.php?t=167865

Horsepower wise, roughly 10 cfm would equal 1 point of compression. If you could gain 20 cfm in your cam lift range you would get twice as much horsepower gain as you would with 1 point of compression.