Thread: Intake ruuners, cams, compression ratio

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My thinking is that with a large cc port you need to be able to flow a large amount of air. If you engine is not pumping enough air especially at low rpm and you are running heads and a cam that are too large for the displacement the motor will not make power. If the cam, intake runner and displacement are matched well, then the motor will be able to make power across most of the rpms. My question here is what effect does compression ratio have on cam and head choice? Why does a large intake runner require more compression? Is this because with a smaller volume cylinder pressure at spark is greatly increased causing the motor to spin up quickly and pump more air at low rpm? Does that make sense to anyone?

the more head cc intake runner the hire the rpm . more rpm the bigger the cam . dura @050and lift somtimes more over lap then you need cr to make it run. but small ports better port velocity better respones fuel air mix better at low rpm . big ports low rpm no cr = a pig. not tring to pi$$ you off but your 502 will make tq why are you so worried about hp? i am not saying you can not make 600 hp with 9to1 502 with hyd roller cam but a have built a lot of big blocks and i wound not try to build a big block with a small cr and a hyd small roller cam and big ports .and this work from a 396 to 632

i have decided to go with much smaller heads, 290 cc runners and 110 cc chambers. Im going to build the sallee chevrolet super street 502......i didnt understand before that the 325 runners were way too much for what i have. I thank you for sending me in the right direction

i think you will be very happy with the smaller ports this will work good