Quote:
Originally Posted by AL427SBF
Agree if you use those VE and RPM numbers, if you come down to .85 VE and 6000 RPM you get a different picture. All of this warrants an explanation from my engine builder, I need to undersatnd his size selection criteria.
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Holley's own formula, basically the same as the one you posted is simple:
cubic inches X max. rpms, divided by 3456, multiplied by the VE......
assuming 90% VE and 6200 rpm max, your engine would be pumping 689.43 cfm's of air thu it..the general concencus is to have a carb capable of 50 cfm flow more than your max...so you would need a carb capable of flowing 739.43 cfm's or a 750 carb.......the 650 will work, and you'll have tons of low end torque and great off-idle response and if that's what you want, then you'll get it, but you'll be giving up in the upper rpm range......
a well built engine should be in the 95%+ VE range......
The 331 stroker I built in my garage had a VE of 96.04% at 6000 rpms on the dyno,at 3500 rpms, it was 90.98% and steadily climbed thru the rpm range to a max of 96% and I'm no great engine builder by any stretch.....
David