Re: engine decision's... I have made up my mind.

[Shawn C Meze <skerocdriver@juno.com>]

On Mon, 6 Aug 2001 15:10:40 -0400 "Scott F. Williams"
<sfwilliams@home.com> writes:
>Let's kill the myth that backpressure helps an engine. NO ENGINE 
>BENEFITS
>FROM RESTRICTION IN THE EXHAUST SYSTEM! 


Sadly, I couldn't disagree more. 
While the ultimate goal for any performance engine program should be to
eliminate as much backpressure (restriction) as possible, its been proven
by more teams of variously different racing organizations that some back
pressure does help produce more power. 
Hell, even in the funny car I drove years ago we made restrictive bends
in the zoomie headers to help with this.

Like anything else, finding out exactly how much is restriction is
ultimate for your application, is the hardest part. 

As an example, my last dyno day showed me that the Eurosport headers I
put on the 82 Roc did in fact loose power over the dual outlet manifold.
I felt it "seat of the pants" that it was not as good as before but the
numbers from the dyno I saw as a result really disappointed me. Large
diameter tube runners are best suited for high compression motors. (like
the 11.4-1 CR that's in my 84.)

If I can find a Pacesetter header (small diameter runners) ill use that
on the FSP car at a later date. For now, the dual outlet manifold works
best on my 9.2-1CR motor. In fact, im gonna swap the header in the 82 for
the dual outlet manifold that's in the 84 real soon.

Another fine example was at the Pro Solo event at Atwater. On my last run
after I launched from the start, the exhaust system pulled apart behind
the header at the slip joint. It was REALLY loud, sounded really bitchen
but I could feel that the torque it had wasn't there anymore. My time
showed it as well. No pull off the corners. When my exhaust is on and
tight, its fairly decent power wise. Any leak at all and its a dog. Some
restriction is a good thing, always. 


Shawn Méze
86' Jetta GLi 8V       84' Scirocco 8V           88' Corvette -SS 30-
82' Scirocco GTi -FSP 54-     79' "Project FSP Scirocco"
The Fastest, Quickest, Cleanest and best looking Scirocco in all of San
Diego!
http://www.Geocities.com/MotorCity/Speedway/1308/index.htm

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