Originally Posted by Caballerokid
How would someone go about selecting an intake runner size rather than someone just saying I should be ok with such and such? How would I know what to pick, say a 165cc, 170cc, 180cc, 195cc, 200cc, 210cc, 215cc, 220cc, 235cc etc... The 235cc will flow the most air because it's bigger. Why would 180cc be ok for my setup? Help me understand why. Thanks
The volume itself is actually meaningless. What you're concerned with is the minimum and average cross-sectional area. A typical sbc intake runner length is about 5.6" so given the volume you can easily figure the average area.
As a general rule the more rpm you turn the larger of cross-sectional area you'll need. Also increased displacement requires more area. For a street engine you want to go with an adequate volume and no more. Bigger is not better, smaller is not better- just right is better. If you do have to go slightly larger or smaller go a hair larger.