With stainless steel you have the further problem of stress corrosion at
these temps weakening the material.  I have a "type A" configuration on my
20B, but using inconel.  Do you suppose it is still a problem?

Al Gietzen

Al,
I don't know for sure what would happen with Inconel, but I would keep a very
close eye on it once you start running the engine.  Also, I would be very
interested in hearing how it works out.

I am basing my comments on the experience a friend of mine had when working
at Ford years ago.  They were testing a "thermal reactor" for emissions
reduction (prior to catalytic converters) on the exhaust system, which had to
be very close to the manifold to keep the temperatures up.  The configuration
was very similiar to the "type a" description of muffler.  They had fatigue
cracking caused by the thermal expansion on heating/cooling cycles. According
to him, they never really solved it before the project was cancelled in favor
of catalytic converters.  I am not sure what kind of expansion/flex joint can
be put in this configuration.

Paul wrote:

Tracy was pushing his luck with .035 SS.
You could put a slip joint in the muffler if it proves to be a problem
with type A mufflers.

Paul,
How do you accomplish a slip joint in a type A muffler? Where does it go? the
header tubes are typically welded to the side of the muffler, and it is the
axial expansion of the muffler that is trying to drive the header tubes apart
that causes the fatigue strain.

Bill Schertz

You make the muffler in two pieces. The aft or forward part is slightly
larger and slips over the other part. This is very common in aircraft
turbo exhaust systems.
 
Paul Lamar
 
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