Overlap Triangle

You wouldn’t put fully ported B1 heads on a 408 inch big block with 9:1 compression and a peak power rpm of 6k would you? I know I wouldn’t do that.

Nor would I build a 632 big block with 915 castings (or any other garbage head like that) with 15:1 compression and peak power at 8500.

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No i wouldn't and the reason is the air velocity would be to low for the 408 and too high for the 632. I liken it to sucking on a straw where my mouth is the piston, the straw is the port and my finger covering the end of the straw is the valve. How far i move my finger from the straw, how fast i move it and how long i hold it away affects velocity. I will dig out my book and take a look, i guess i missed that section somehow.