Data from drag strip

[Marteney, Steven J.]

Don't forget about resonant tuning.  It works on the "out" side as well as
on the "in" side.  There COULD exist an exhaust system that would outflow no
exhaust system at all, under certain conditions.  And, even it may be only
.05sec below that.  All in what you're going for.  Only takes .001 (or is it
.01?) to set a new record.  

There is at least one "bible" on the subject.  I have the book at home and
can get you the title if you want.  (Not to mention ye olde college physics
book.)
Steve

-----Original Message-----
From: Roger Heflin [mailto:rahmrh at cableone.net]
Sent: Monday, May 28, 2001 11:00 PM
To: gmecm at diy-efi.org
Subject: Re: Data from drag strip


Bruce wrote:
> 
> There are 11 sec GNs using a single 3".
> Just a matter of what you wanna spend,  I think some folks get overly
> carried away.  Muffler type has as much to so with it as anything.
> Bruce
> 
> > Is there an ideal threshold for WOT exhaust backpressure which defines
the
> > point at which attempting to reduce EBP further would yield very few
gains
> > in a hot street car with a matching cam grind?  Has anyone ever seen a
> > rule of thumb correlation between EBP and lost HP?
> > Walt.
> 

I am running a Borla exhaust, hooker long tube headers (93 Z28 409 LT1).
The borla is a 3" single, and the long tubes are 1.75 each into 3"
collectors.

The car has run a best of 12.21 through the full exhaust and a best of 
12.11 through cutouts (dual 3" cutouts).   So my exhaust is not holding
me back terribly much.   

Given the small difference between exahaust and no exhaust, I really cannot
do much better with any exhaust system, since no exhaust only gets about .1.
I was suprised based on what the aftermarket exhaust people say about 
exhaust size.   My car should be running just over 400hp.

				Roger
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