Re: Race Header Benefits?

["H Jones" <hjones1@airmail.net>]

I have tested 3 different exhaust manifolds on my Scirocco and here are my
results....

1. "Tri-Y" - marked increase in low to mid-range power, very minor
improvement in hp above 5700 rpm

2. Stock VW Dual Down-Pipe Manifold - Similar results as the Tri-Y, with a 1
to 2 hp drop across the power-band (The Tri-Y did slightly better)

3. 4 into 1 Equal Length System - The best over-all performance, with much
better top-end (over 5700 rpm) results. Without a doubt, the best solution
for a hi-rev race application!

My choice was the 4 into 1 system! If the primary application was for street
driving, I would opt for the tri-y (more low end torque and MUCH cheaper).

All three manifold systems were tested with a 2" diameter exhaust, with no
cat and no muffler. All test were conducted on the same dynometer over a 2
day period.

The header / manifold is vital for making hp, but don't overlook the exhaust
system (down-stream of the manifold) design. I have run 4 different exhaust
system designs and the one that makes the most hp runs 30" perfectly
straight from the end of the header and then angles (hard) to the driver
side, exiting just aft of the driver and before the rear wheel.  This
exhaust system is LOW, extremely loud and does not come even close to being
street legal, but many of the lessons can be applied to a street-legal
exhaust system (the section just aft of the header junction should be
STRAIGHT for at least 30").

Harry

----- Original Message -----
From: T Berk <tberk@mindspring.com>
To: <scirocco-l@scirocco.org>
Sent: Sunday, July 18, 1999 6:44 PM
Subject: Race Header Benefits?


>
>
> Listers,
>
> My '81 came w/ a 4 into 1 header installed. I have since swapped in a
> GTI 1.8 liter engine. The only other mod at the moment is a K&N filter.
>
> I have at my disposal a dual exhaust and wondering what the header
> benefits me- high RPMs with more flow? Greater torque? Loss of low end?
>
> tia,
> TBerk
>
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>
>


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