> > 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 occurred 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.
Joe Hull
Cozy Mk-IV N31CZ (65 hrs - Rotary 13B NA)
Redmond (Seattle), Washington
I don't know if it's applicable here, but I have heard that stainless is
welded, the back side of the weld needs to be in an O2 purged
environment. I wonder if/how that's done when the inside of the pipe is
being welded to a flange..
Matt-
That is true for tube butt joints such as headers. You need a
separate supply of nitrogen gas behind the weld. Not so for a
flange welded on the end of a tube as the slag, if any, can be
mechanically removed.
Paul Lamar ...No rotor no motor.
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