AZDoug

This is my first post, and I am asking here, because I have seen more intelligent answers here than anyplace else, so:

I am needing to figure our what size induction piping/tubing I need to funnel about 700 CFM (WOT) into a 1000 CFM throttle body.

The T-body has 9.62 sq-in of throttle plates.

3.5" tube has an ID of about 8.3 sq-in of cross section, 4" tube has about 11 sq-in of cross section.

I need to run about 36" length of induction piping from the air cleaner box to the throttle plate plenum, with either one 90 degree bend, or two 45 degree bends. (This is a custom speed density system system w/ four barrel style T-body, not a LS1 type MAF)

is 3.5" OD tube enough, or should I go 4"?

Anybody have any leads on T-body "hats" that will flow 700 CFM at 7000 RPM on a normally aspirated engine without significant restriction, sorta like the ones Pro Charger makes for their forced induction systems?

Nothing is stock on this application, which is why I am looking for answers. Application is a real cool 1961 Corvette, in which I need to use the original Mechanical FI air inlet (4.5") next to the radiator as my air feed to the air cleaner box.

Already have the exhuast worked out, but not much info is available on engineering non-stock induction flow requirements.

Thanks,
Doug

300bhp/ton

Not sure if this helps or not, but according to David Vizard 1 sqaure inch of tubing should flow ~115cfm, he is talking in respect to exhausts, but the theory should be the same.

Zeus

if I'm not mistaken, the CFM rating of a piece of tubing is proportional to the pressure it's measured at (or in this case vaccuum). You can make a soda straw flow 700CFM if you put enough force on the gas. I think you need to figure out what pressure you want it to flow at first. I'm assuming it would be the pressure you reach at full boost.

Anyways, there's a chart floating around this forum that has flow capacities of straight tubing at I believe 28" of water. That might be a start.