Date: Tue, 19 May 1998 12:59:51 -0400
Reply-To: Erik O <koesel@UAKRON.EDU>
Sender: Vanagon Mailing List <Vanagon@vanagon.com>
From: Erik O <koesel@UAKRON.EDU>
Subject: Inline Exhaust Theory: part II
Content-Type: text/plain; charset=us-ascii
Just to sum up my decision on using the "dreaded stock manifold". During
my search for the ultimate exhaust system for my van, I heard a lot of
suggestions from people I would consider to be experts on VW's and
general automotive theory. Most all of these people agree that engines
need some amount of back pressure and back pressure and low end torque
go hand in hand. If you assume the internal volume of the Golf manifold
is X, then alot of these "trick" headers could be assumed to have a
volume of 2X. At least double. While this may work out well for a small
passenger car, my big Westfalia might be better off with the Golf
manifold. VW engineers weren't off by that much in the design of the
"dreaded manifold". Plus considering how thick the sidewalls of the
manifold are, I can always bore it out a couple mils to decrease back
pressure a bit. The experts also agree that a good pipe flow is helpful
for performance, which I've accomplished and I'll explain later.
Finally, one last note on backpressure, flow, exhaust manifolds, and
trick headers. All of the experts agreed that the number one way to get
more power from an engine is DISPLACEMENT. Trick headers, MSD ignition,
K&N filters all might help a little if the stock parts they're replacing
are inadequate, but for true performance gains, displacement is the key.
So unless I'm going to bore out my engine, I'm not missing out on too
much with my exhaust.
Alright, now I have this donut outlet manifold to finish up with the
rest of the exhaust system. The Golf manifold I'm using isn't like most
I have seen. The outlet does not come out in the center like most I've
seen. It comes out straight, but closer to the left. The hole faces
perpendicular to the driveline, just closer to the port on the left, if
not right in line with the left center port. This clears the mount
easily. I picked up the round half from a downpipe at a boneyard. This
is the piece that accepts the other half of the spring clamps. The rest
of the pipe I'm using is 2" ID and for all the bends I'm using header
pipe made by Hooker Headers and purchased locally at Summit Racing in
Akron, Oh. These are beautifully made mandrel bent pipes. I purchased
two of these, 180 deg mandrel bent with 3" radius and 6" and 15" legs.
The first one I cut for the downpipe at around 120 degrees in the bend
to fit in the 2" hole I drilled in the downpipe bracket from the
junkyard. This was then welded together by a pro welder, definitely not
me. This left me with the pipe close to the driverside rear wheel (not
too close) perpendicular to the driveline. From here I cut the other
header pipe in half at 90 deg in the bend to leave me with two 90 deg
elbows. Connecting these with a little cutting and "temporary" u-bolts
and I have a 2" pipe facing the passenger side of the van behind the
engine. This is the "stock" position. Then a 30" length of 2" straight
pipe and a "turbo" high flow muffler finishes the job. Also, good
exhaust hangers all around to support everything. (All that was hard to
describe, you might have to wait for the pics. Sorry.)
Everything's together and tight. All supported by exhaust hangers bolted
through existing holes in the frame. Time to fire up. VROOOM! WOW IS
THIS THING LOUD!. Actually, it wasn't that bad, just a little too much
for my tastes. Drove it around for awhile, great power and performance.
Just a little too LOUD!. Back to Summit Racing for an additional
muffler. Didn't want to screw up the flow too much and as a joke I
bought a glass pack to install in place of the 30" straight pipe along
the rear. Much better after that.
That's all for now. When I get the pics down I'll have a better
description on my site. I just hope that I find this all to be worth it.
I could have just used a stock diesel manifold. I know a guy that's put
80k on his van running the stock manifold. He drives to most of the east
coast shows and tows an enclosed 4x8 trailer, doing 70 all the way.
Still has tons of power and gets good mileage all the way. Which was
actually one of the other reasons I used the golf manifold. It flows
much better than stock, and stock still works good. Later.
_______________________
Erik O Akron, Oh
82 GTI Westfalia
http://ebyte.com/gl
http://ebyte.com/wow
| 
