exhaust flange-pipe interface failures

  We feel that this exhaust was not cracked for long
 before total failure.  As someone else posted earlier, it is easy to
 be a Monday morning quarterback!  Many more answers to the questions
 which are generating much conjecture will be available on our website
 soon.  Thank you all again for your patience. Keith Holm Powersport
 Aviation
 Keith,

Here is another way to keep stress off of the flanges. A slip joint just
outboard of the header flange. The tabs should have heavy springs pulling

the

two halves together. For aircraft use, an additional hole in each tab

inboard

of the springs will allow for a 4130 strap to connect the inboard holes.
Holes in the ends of each strap align with these holes in the tabs. AC

bolts

with jet nuts go through the straps and tabs and are just torqued to just
short of tight. The pipes can move around during operation.

This is used on race cars around the world. Another method is to have the
tabs long enough to pass each other, and a hole through both tabs lines

them

up, and a single bolt does the same thing. My muffler weighs 10 pounds. I
wouldn't dare hang it on the engine. Failure of a tube would be immediate.

did that already. I also hammered a SuperFlow muffler to pieces. I also
melted the end off of a steel bodied steelpack muffler. I also melted a

piece

of tunnel sheet aluminum and overheated a Halon fire bottle. It went off
during the race and scared the bejesus out of the driver. I also melted

the

outside of a tube bend and boiled the fuel out of the carb, even with a
shield in between. The header tubes squirm around during operation. They
don't move far but have a great amount of force. The tubes have to be free

to

move. The muffler weight and even the header weight cannot be hung on the
engine. They are running bright orange at 50 degrees lean of peak EGT.

Even

stainless looses some strength at 1,700 degrees.


Lynn

Lynn;

What alloy do you guys use?  SS (like 321) will fail much more easily at
1700 than inconel; especially if under any stress loads.  It gets
inter-granular stress corrosion and loses it strength.

Al


 
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