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Re: Air Scoop Formula

To: "Thomas E. Bryant" <saltracer@awwwsome.com>
Subject: Re: Air Scoop Formula
From: DOUG ODOM <popms@thegrid.net>
Date: Sat, 12 Feb 2000 10:23:43 -0800
Tom, I'm confused (more so than usual). Are we talking inches of water
or pounds?
                        The other doug in rainy arroyo grande, ca

Thomas E. Bryant wrote:
> 
> Thanks for your formula it is a bit more scientific than mine. I guess
> I'm just a "seat of the pants" type guy. Tom Burkland did say that the
> scoop should bring you to sea level efficiency if it is working
> properly. He claims 8 lbs. of pressure measured in the scoop on their
> former Comp Coupe at 300 MPH. Others have said the static pressure is 1
> 1/2 to 2 lbs at 250 MPH.
> 
> Tom
> 
> "Lawrence E. & Cathy R. Mayfield" wrote:
> >
> > Hey Tom, good job on the formula! I had went about it a little differently
> > though but with the same, I hope, results!
> >
> > I developed the following:
> >
> > Inlet Area (in sq) = (Disp * RPM *VE) / (MPH * 2112)
> >
> > Where: Disp is engine displacement
> >        RPM is RPM at which you want to run
> >        VE is volumetric efficiency of engine (1 if you don't know)
> >        MPH is the at which you want to run in MPH
> >        2112 is a combination of conversion factors)
> >
> > So, an example... my car, 306 CID, 200 MPH, 6250 RPM, .8 VE
> >
> > Inlet area = (306 * 6250 * 0.8) / (200 * 2112) = 3.622 in sq.
> >
> > This provides for an exact balance of the engine needs. I would use a
> > volumetric efficiency of 110% to account for some ram air effects, however.
> > This is an interesting equation because the slower you go the larger the
> > scoop. I think this means that when testing on the dyno that you need a
> > large plenum and inlet. Tom, does your equation do this also?
> > Unfortunately, adding a scoop or the inlet adds some drag to the car, but
> > if confined within the frontal area envelope, shouldn't add much, if any.
> >
> > Neat stuff, this!
> >
> > mayf
> >
> >

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