Hey Don, I'm back for more info LOL.
Alright I want to know if there is any kind of mathematical formula for determining optium intake runner size in terms of both VOLUME and CROSS SECTIONAL area with a given CID and RPM window.
Let's look at two different engine Combo's:
First a 422" Small Block Chrysler with a 4.10" bore, 4.0" Stroke, 6.300" Rod. Max RPM will be 7200-7400
The Other Motor would be a 342" Small Block Chrysler, 3.94" bore, 3.51" Stroke, 6.125" Rod. Max RPM 7800
And let's assume both are going to be 13:1 on Gasoline, and both will have very similar Solid Roller cams, ~274 @ .050" .675" lift on a 108 LSA.
Now, Am I wrong here in thinking that the 422" motor will NEED a lot more runner volume and possibly a little more cross section to work effectively compared to the smaller motor? ie. The 342" motor actually exists, I have seen it with a set of 215 CC intake runner, 2.95" Cross Section W5 heads.....It REALLY works well. Made ~625 HP on the Dyno.
Now IMO bolting those same heads on the 422" short block, will not gain me as much as possible, because I'm thinking they may be too small.
I've been looking at what Chapman Racing Heads has been putting on some of the older Mopar Sprint car motors. at 410", 8000 RPM on ALKY they are using a 269 CC intake runner in a W7 head and making ~795 HP. On the same flowbench, those 269 Runner CNC'd 2.18" heads really are'nt blowing away the 2.08" 215 CC runner W5 in terms of airflow. They are ~15 cfm better at .500" and ~18-20 better at peak of .700". Not a huge gain considering the 54 CC larger runner, larger valve and taller short turn. But I know there is more to making power than damn flow #'s. That's why I want to know if that Large Runner CC was done on purpose.
I'm thinking for the 422" motor I will raise the runner and widen it. Epoxy the floor, increase the Cross Section to ~3.0" and Runner volume to ~ 245 CC's.