Dave,

 

My "muffler" is a copy of this design. Except its made of Inconel. Unfortunately it doesnt really serve its intended purpose of muffling as you know. Could be my implementation as the center tube diameter could be too large. I expect it will still be holding up just fine when I replace it because it doesnt muffle. I'm thinking of trying the DNA muffler next pending Mark's final results.

 

One more data point. My buddy has a Cobra kit car with Ford 302 V8. His side pipes also use the spiral flow design. The external pipe is 4" diameter, the internal is less than 1". So presumably a large percentage of the flow goes through the spiral. But his car is still pretty loud.

 

Mike Wills

 

RV-4 N144MW

----- Original Message -----

From: David Leonard

To: Rotary motors in aircraft

Sent: Thursday, July 09, 2009 7:38 PM

Subject: [FlyRotary] Flowmaster Hushpower Report

For the last couple hundred hours I have been using a Flowmaster Hushpower II muffler.  Also used by Tracy and some others I think.  It is done.  The outside held up wery well, but I reciently removed it and discovered that the insides have entirely disientigrated.  Whatever they used as packing has turned to a heavy clay-like substance ratteling around in the bottom.  She steel mesh is in pieces.  I had been thinking that the plane was not as quiet as it seemed 2 years ago..  go figure.

 

So I was thinking about one of the DNA Mufflers someone mentioned.  They seemed nice because there is no packing, just steel dividers.  Unfortunately, it is a little to big around to fit in my current set up.   Instead, I ordered this muffler that also has steel innards but no packing:

http://www.moroso.com/catalog/categorydisplay.asp?catcode=35054

 

It is nice because it is going to be smaller and lighter than the flowmaster (or the DNA), as well as less expensive - even the SS version that I ordered.

 

Will report back in 2 years on its performance  :-)

--
David Leonard

Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net
http://RotaryRoster.net