* What wall thickness was the 321 stainless exhaust tubing  Keith?

Paul Lamar

Keith Holm wrote:

16 gauge, or .065".
Keith Holm
Powersport Aviation

Wow! .065 thick 321 and it still broke in only four hours. Hard to believe.
Must have been a defective weld or he cantilevered the entire ridged

exhaust

system off the flange with no braces and it vibrated at a sympathetic
resonant frequency. Either that or that PowerSport PP 13B is one powerful
motor :)

Tracy got 650 hours out of this .035 thick SS muffler.

* Paul,
There were likely many factors contributing to the exhaust failure.  As I
wrote, the system was unsupported, and likely was in resonance.  There was
also no room to allow for the differential expansion of each header tube.
The weld did not appear to be defective, but there are problems associated
with welding thin wall tube directly to a heavier flange.  Pictures of this
will be up soon.  The system probably had closer to 20 hours on it
considering the extensive ground testing that Kerry performed.  You are
right of course that the Powersport RE-215 is one powerful engine, but not
in any destructive way!!
Keith Holm
Powersport Aviation

Paul Lamar

Keith,

  Are you saying that the failure was at the point where the head pipes
were welded to the exhaust flanges (at the engine)? If this was reported
before sorry for the repetition - I must have missed it. I'm putting
together a header right now using .065" 321 and had planned on slip
couplings where the primaries enter the collector. Sounds like maybe slips
should be considered at the engine end of the primaries as well.

  Thanks very much for the info on this failure Keith.

Mike Wills

 
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