Mailing List flyrotary@lancaironline.net Message #29938
From: Todd Archer <archerw@ubtanet.com>
Subject: RE: [FlyRotary] Re: Mazda mufflers
Date: Sat, 4 Feb 2006 10:24:51 -0700
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>

I’ve wondered about the suitability of the Racing Beat presilencers.  I don’t think it’s SS wool but wider strips of SS they use to fill it.  That’s the first thing the exhaust sees after the header and I know they hold up.  This is everyday car driving, too.  Lynn, do these things hold up at all in race duty cycles?

 

The case is ¼” mild steel, I believe, so there would be a weight penalty off the shelf.  Maybe these innards and a SS can. 

 

Todd Archer

 

 

 

 

 

The problem with fillers, or packing if you like is twofold. The usual glass like material used in piston engine mufflers, just melts. If you catch it quickly, you may get to see the glass balls before they are machined away and vanish.

 

If you try a ceramic blanket material like I did, you discover that the hammering of the exhaust pulses mechanically decomposes that material, or any material into fuzz and blows it out.

 

The race car muffler has small tubes with thousands of small perforations. A 4" perforated tube down through the center, with 5 additional smaller perf tubes inside of that tube. Still under 100 dB at 50 feet after 7 years of service. It looks like the Burns mufflers but is very much larger and is about 27 pounds. The Burns mufflers look like the way to go to me. They offer stainless swarf packings which might hold up for quite a while.

 

Years ago, there were mufflers (very big and heavy) used in Mazda race cars that had Lava Rock fillings. There was a bung with a screw in plug so you could refill the lava rock after each race. The Mazda just turns it into dust with the hammering.

 

Lynn E. Hanover 

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