> >     Yep, that's who's design I copied - I even bought my 6" inconel tube
> >     from
> >     him because he had some left over from his muffler.  The welder used
> > the
> >     inconel welding rod that I bought. So I know it was the right stuff.
> >
> >     The exhaust flange joint is welded both on the outside joint and on
> > the
> >     inside joint. There is no possibility of weld failure there - the
> pipe
> >     itself would have to tear/crack.
> >
> >     Like I said - Inconel doesn't live long when there is flexing. So,
> > maybe
> >     Atkins has his muffler supported and mine wasn't - although I've
> >     seen his a
> >     few times and didn't note any supports close to the can.  It does
> >     look like
> >     he has a tab for support down the line a ways - that may damp out
> > enough
> >     vibration to keep the flexing under control. For sure something was
> >     different!
> >
> >     Joe Hull
> >     Cozy Mk-IV N31CZ (65 hrs - Rotary 13B NA)
> >     Redmond (Seattle), Washington
> >
> >     -----------------------------------------------------
> >
> >     The exhaust always breaks just next to the weld for some strange
> >     reason so the flange actually supports the tube.
> >
> >     Here is some more info from Marks Wrathal site on welding
> >     tube to exhaust flanges. Many many racers do it all the time.
> >
> >     http://www.wankel.org/
> >
> >     " Weld only the engine side of the flanges. Four spot wells on the
> >     header side seems to be the way to go. Belt sand the flange faces
> >     then lap them on a piece of glass and a piece of oiled wet or
> >     dry paper."
> >
> >     "Archie backed up this crucial point as follows:"
> >
> >     "In hard core racing, the same problems (as occured on N214KW)
> >     arose a number of years ago, mostly in funny cars, but dragsters
> >     also. The common denominator, other than various grades of
> stainless,
> >     was outside welds. Now you may see some tack welds on the outside,
> >     but the actual welding is done on the backside.(inside) Also in
> >     current use is a tube within a tube. I noticed the weld bead was
> >     quite wide, increasing the hazard, and may have contributed to the
> >     failure."
> >
> >     Archie builds 7000 HP AA drag engines for a living and has several
> >     forums at OSH.
> >
> >     This last trick is expensive but Everett Hatch came up with the
> >     idea. A ball flex joint is used right next to the block.
> >
> >     Paul Lamar ...No rotor no motor.
> >
> >
> > Paul and Joe,
> > The more I learn about Everett Hatch the more impressed I am. The ball
> > joint he uses would almost double as an anti-reversion cone. Besides
> > relieving the pipe to block stresses note that the pipes just down
> > stream also have inside slip fits. Very nice work.
> > Bill Jepson
> >
>
> Were the welds heat normalized afterwards??
>
> Gary Buster
>
>

I don't know if mine were heat normalized. Does that help the surrounding
metal? Because again, it wasn't the welds that broke - just the inconel all
around the joints.

Does heat normalization reach the expected exhaust gas tempatures? If
not, wouldn't the tempatures reached by the exhaust gases make it a
mute point.