math help for TB recremendation
 

i know how to figure out the CFM a motor needs but where do i get CFM ratings for TB's?

motor in question is a 408 with AFR 185's,custom cam,Spider intake(vicjr with elbow for TB and injector bungs welded in) ..those heads wont breathe much above 6200 with 408cu so figure that to be the max RPM..i am guessing in the neighborhood of a 75mm or 80mm..thanks in advanced..

BTW the dyno pull to achive the power that i build "my" combo after was used with a 750cfm demon

Thats one awesome set-up. If it were me I would go with a 80mm TB due to the large displacement of the engine.

Later,

I found this searching for the same answer.http://snow.prohosting.com/~johngift/intakefab.html .The formula is near the bottom of the page have to convert mm. to inches.hope this helps.

the bottom of this page lists some flow data for mass air sensors and throttle bodies.
http://www.kellnet.com/chambers/intake_flow.htm

going by this data, and assuming that the diameter is in linear proportion to the flow rate, then here's what a couple other TB's would most likely flow
80mm: ~960CFM
85mm: ~1070CFM

is that of any help?