Date: Sat, 8 Mar 2008 20:28:37 -0800
Reply-To: Alistair Bell <albell@SHAW.CA>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Alistair Bell <albell@SHAW.CA>
Subject: Re: I4 conversion exhaust
In-Reply-To: <353272.37479.qm@web35808.mail.mud.yahoo.com>
Content-type: text/plain; charset=US-ASCII; delsp=yes; format=flowed
let me chip in...
I have found the stock diesel muffler hanger system to be fine. No
cracking or such in 14 years. I have replaced the rubber isolation
mounts twice. no flex coupling in actual pipe.
I used the stock diesel exh manifold, pipe and muffler for quite a
few years, then switched to the Audi 89/90 4 into 2 manifold and an
aftermarket muffler. But still used the stock diesel muffler hangers.
Friend with similar conversion has had many cracked pipes with rubber
hangers supporting muffler. I believe having the exhaust system
coupled to the engine all the way is the best system.
some info is on my website.
Alistair
On 8-Mar-08, at 7:58 PM, sam mccarthy wrote:
Neil, with my I4 vanagon I had 2 different exhaust designs with
radically different results. The first set up I had built at a
exhaust shop using an old Dasher dual outlet manifold, which angles
toward the front of the van. I had the shop follow the example I had
seen on a German engine conversion site which ran the exhaust forward
through the aircooled heater tube hole, forward to a muffler hung
under the center of the van, into a 180 degree bend back toward the
rear and then out to the driver side ahead of the rear wheel. This
required a simple layer of sheet metal as a heat-shield to keep the
heat away from the floor, but worked very well and was almost too
quiet. No vibration problems whatsoever. My only concern was that
the cat was a bit too close to the transaxle. And, I liked having the
exhaust coming out of the side of the van, as it told those
discerning van-heads that this was no normal air-cooled van.
When that exhaust began to fail, I had the same shop build another
one. When I requested they build it further away from the transaxle,
they suggested going to the stock location, and thought they could do
it for similar costs. It was a mistake. Not only is this a much
more costly design to construct, but vibration problems are a too
often occurrence. It took three redesigns, and a lot more cash
before the vibrations and resulting cracking were solved. And, with
the short length of the stock design, it is often quite loud. I think
the secret really is using a flexible coupling between the downpipe
and the bend to the back of the van, and using rubber hangers to
suspend the system along the back of the van.
With my TDI install, I would rather go forward once again, but the
1990 body I'm using, there is no heater tube hole to route through.
I'll have to go rearward.
If you are looking for the right manifold to use, take a look at
Frank Grunthaners' post in the archives, or within Vanagon.com as he
has done extensive testing on the various possibilities and found
that the Audi 80/90 dual outlet manifolds are the best. The Dasher
manifold I used worked well, but doesn't flow all that well.
Good luck, I hope this helps,
Sam M
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