Al Gietzen wrote:

I have an inconel tangential manifold/muffler on my 20 - photo

attached

(made by

Mark (can't remember last name), a la David Atkins).  The inconel

tubes

extend

through the heavy Racing Beat Flange, but are welded on the

outside -

not on the

inside.  Although having the tubes go through the flange may have

made

the

welding easier, I'd guess that once you get that weld bead around

there

the

resulting strength is no better then butting it up and wleding it.

Seems it

should be welded on the inside end so the flange can support the

loads

on the

tube. There obviously will be significant thermal stress set up and

the

unit

expands and the engine doesn't. Atkins has the same approach on his

13B

and it

seems to be fine.  The distance between the ports is much less on

his.

Am I

worried about mine?  Yep.  Short redoing a very expensive piece,

I'll do

frequent inspections.

Ick.  Those short headers from the exhaust flange to the muffler are

going

to

crack at the muffler and/or the header.  Abel Ybarra (sp?) I think had

some

Inconel bellows on his exhaust system.  If you can find *2* (not 3!)

such

bellows,

have the #1 and #3 rotor's headers cut out and replaced with the

bellows.

The #2

rotor's header would continue to rigidly mount the muffler, and the

bellows would

allow things to move.  The muffler would need a non-rigid weight

support

to help

prevent cantilever cracking.

I need to get Rhino so I can draw what I mean.

Russell Kent

Not necessarily Russell. If all three outlets are tied
together with a Racing Beat type exhaust flange it might almost
track the expansion of the muffler.

Paul Lamar

Russel:  Don't need a picture; I know what you mean.  If it were to

crack

most likely at the heavy flange.  The thinner wall Inconel of the

muffler

will allow some give.  I would feel much more comfortable if the weld

had

been done on the backside of the RB flange.

Paul:  You have a good point.  The flange is insulated from the engine

by

the stock exhaust flange gaskets, so it will likely get quite hot and
compensate for some (how much?) of the muffler expansion.  The attach

bolts

will allow some give between there and the block.

Al

Jim Kidd wrote:

Has anyone considered using titanium for the exhaust system? Its not that
difficult to weld if you apply the right shielding techniques, and the
materials are reasonably available although more costly.
Jim Kidd

Burns Stainless does not recommend it for rotaries or turbo charger
systems. They claim 321 and Inconel are better. Burns has a new,
more informative catalog out. I recommend getting one.

Paul Lamar
 
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