Exhaust manifolds, MC1/MC2/KH/UR-Q, How about an exhaust flex connection??

[Martin Pajak]

I have not heard anyone mention exhaust flexible connections.
In the industrial applications an exhaust flex is a must.
It isolates the rest of the exhaust from not only thermal expansion and
movement but also from vibrations.
I installed one in place of the CAT and it works great, maybe that's why my
manifold has not cracked yet (I did not install a new motor mount).
Just $0.02 CDN = $0.00 USD

Cheers
Martin Pajak

http://www.quattro.ca

1983 Audi Ur-quattro (262,000 km) for sale : (
1985 Audi Ur-quattro (141,000 km) Euro spec. import ;o)
1986 Audi 4000 S Quattro (442,000 km) with 5 bolt pattern


> -----Original Message-----
> From: quattro-admin at audifans.com [mailto:quattro-admin at audifans.com]On
> Behalf Of QSHIPQ at aol.com
> Sent: December 17, 2001 8:03 PM
> To: quattro at audifans.com
> Subject: Exhaust manifolds, MC1/MC2/KH/UR-Q
>
>
> --
> [ Picked text/plain from multipart/alternative ]
> Way oversimplified IMO/E.  Most chipped cars will find signs of EM cracks
> even with fantastic motor mounts.  Cracking also occurs *within* the
> manifold, specifically at the collector on cars that have been
> run hot and/or
> lean.  Manifolds without support are more prone to heat/stress
> cracking than
> ones that aren't, regardless of engine mount condition.
> Unfortunately, the
> 5kt/200t are the ONLY audis I5's built that don't have support
> for the turbo
> and/or EM.  The early urq's did, the later S cars did, the 20v
> N/A cars do,
> the 10v N/A cars do.  If you look at Corky Bell's book on page
> 126, you can
> easily see the problems with a long log style manifold vs heat.  He lists
> expansion rates of .1in/ft for your typical cast iron log
> manifold.  He also
> suggests considering two piece manifold designs to address the
> problem.  Yes,
> a weak mount can exaserbate the amount of stress placed on the
> manifold, but
> it is hardly the only culprit and reason for cracking.
>
> I don't share the same batting average as you wrt motor mounts "causing"
> manifold cracks.  Audi followed solid engineering practice in going to the
> 2pc manifold design, but stopped short of a good support for the
> manifold/turb.  Then in a simplified and more retroactive
> engineering design,
> they went back to the single pc manifold on the urS car.  The urS
> cars use a
> single piece exhaust manifold that equalizes heat, centralizes the WG, and
> they put support to the turbo.  I've done plenty of motor mounts on S cars
> that carry the same part number as what you reference below.
> Haven't seen a
> cracked manifold  on an urS car yet.  Why not, if what you say is gospel.
>
> Phil you are way off base here, in practice, theory and application.
>
> My .02
>
> Scott J
>
>
> Phil Payne writes:
> >Not yet seen a cracked manifold over a good engine mount.  So
> far the score
> is >100% - fit a good engine mount, make sure it'sprotected (Type 85 -
> heatshield, Type >44 - air duct) and your manifold won't crack.Solve the
> right problem - don't mess >with exotic fixes for the symptoms without
> dealing with the cause.
>
>