Re: Race Header Benefits?

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

Data is critical and the dyno does not lie. Luckily I have access to an
excellent in-ground dyno that was purchased from an auto emissions testing
facility which went belly-up (warms my heart).

My application is pretty unique and may not completely apply to your 84 1.8.
My car is a 1.6L 1980 Scirocco, prepared for SCCA ITC racing. The rules
limit engine modifications, but the exhaust manifold & system are
unrestricted (except exit point and db levels).

The Auto-Tech Tri-Y is one of the three systems that I tested (and ran on
the car for a year and a half). I like the Tri-Y, it is cheap, it is light
and it DOES give more hp. A good "tuned" 4-into-1 header is going to cost
$500 and the best one that I have seen is manufactured by BSI. If you have
the $$$ and your car will be running in the higher rpm range, get the
4-into-1.

The key to gaining more hp with your header / exhaust system is to change
more than just the exhaust system. Get the engine breathing better. Get a
cam that "matches" your desired exhaust system & intake system. I run a
"real" G-Grind (it passes the Scruiteneer's dial test), everything is match
ported, the injection system is modified & adjustable (dialed it in based on
extended exhaust gas temps @ 6000 rpm) and the distributor is fully
mechanical & recurved (UK spec 1.6L GTi unit).

Get the engine breathing, on the intake side and the exhaust side.

----- Original Message -----
From: William J Erikson <williamjosiah@juno.com>
To: <scirocco-l@scirocco.org>
Sent: Sunday, July 18, 1999 9:19 PM
Subject: Re: Race Header Benefits?


> Now THERE is some hard data! Good to see!
> It also makes me feel good, because I have an AutoTech Tri-Y header
> sitting in my garage.
> I didn't expect the increase in low end.
> Just curious, do you happen to have an estimate, from this experience,
> how much difference there is between a completely stock setup on an '84
> GTI (single outlet manifold, cat, 1 7/8" exhaust, normal muffler) and a
> Tri-Y with good 2" mandrel-bend exhaust, like TT's?
> Thanks much,
> Josiah
>
>
>
> On Sun, 18 Jul 1999 19:57:22 -0500 "H Jones" <hjones1@airmail.net>
> writes:
> >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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