Ok try this
take your 225 and figure every revolution pulls in three cylinders worth of air right? So that would be 225/2 =112.5 cubic inches at 100% volumetric efficiency.But that poor stock slanty would be lucky to pull in 70%;so 112.5 x .7= about 80 cubic inches per revolution.
So lets rev it till it floats the valves, say 4200rpm. So now it is gonna pull in 80x4200= 336,000 cubic inches per minute. Ok so converting that to cubic feet is; 336,000/(12x12x12)=194 cfm
But let's say you put a big cam into it and ported the snot out of those miserable heads,And bumped the compression up, and headers etc, and you finally got the volumetric efficiency up to 85%.
Now you are up to 236 cfm@4200, or 281@5000,or 337@6000
Then bear in mind that the efficiency peak is usually at or near the torque peak,not at max rpm. So a slanty-cam that shifts at 6000, might power peak at 5200, and so torque-peak at 4000.
Now you are down to 225 cfm;imagine that!
I am very impressed that you can make a 500 perform.
Yeah, I know;lot's of guys have made it work. And I'm impressed by every single one of those/you guys.
