MAR34807@aol.com wrote:

 A question asked elicited this response; what do you all think?

Anybody know who can fabricate an inconel manifold reasonably?

You'd be insane to do that.  A mild steel manifold would still last ten
years or so, and cost about 1/100th of the price of inconel.  (That's
NOT an exaggeration).

Inconel is an exotic material good for gas turbine blades and maybe
stirling engine hot ends, as well as turbocharger turbines.  You'll
notice that the turbine housing is cast iron though--it's all you need.
If your cast manifold cracked it's because of bad design, not bad
material.

So the answer is no, no-one can fabricate an Inconel manifold
"reasonably".  The stuff isn't meant for this purpose---stick with
regular mild steel and you won't need to worry about it.  You'll notice
that the exhaust system decays first at the tailpipe--the coldest point,
where the water vapour gets a chance to condense and seep into the
gaps/cracks.  The manifold gets so hot this doesn't happen.

Off the record, I believe Inconel 713C costs almost as much by weight as
gold if you buy it in small quantites.

Chuck Harbert is going to disagree with you MAR. Here is a picture of
his relatively low cost Inconel exhaust manifold.

I think you are under-estimating what 1800 degrees F can do to mild
steel.

You might get away with it if it is thick enough. This is not a car
however.
If you are extrapolating from car use ** DON'T! The average temps are 
much higher.

Paul Lamar
 
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