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Date: Sat, 11 Dec 2004 21:28:43 -0600
From: Charlie England <ceengland@bellsouth.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: exhaust design question( race car bark)
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jbker@juno.com wrote:

>OK , Charlie and Lee H, Do the race cars not use the stock exhaust manifold because they are much "bite-ery" than Tracy's engine? When he departed here the other day several people commented on how much better it sounded than his old 13B without splitters.
>
>Bernie
>
I'd bet the racers use headers, followed by whatever it takes to get 
them *just* below the noise limits set by the sanctioning body. It's 
doubtful that the mufflers they use alter the spectrum of the sound 
much, just the level.

I never got to hear Tracy's at full throttle on takeoff, just the runup 
on the ramp while I was standing near the left wingtip. It's definitely 
better than the 13B, but still had that edgy sound once he advanced the 
throttle.

Once you hear Paul's SQ2000, you'll see (hear) what I mean. The best 
description I can think of is that it's like the difference between a 
small 2stroke & a big V-8. The sound is, well, round. (Read some 
audiophile magazines if you want to see real struggles to describe sound 
in print. :-) ) I'm not saying that it was quiet, but it was pleasing 
instead of irritating. I guess a good analogy would be my attitude about 
the sound of a T-6 radial engine (love it) vs. the sound of  T-6 prop 
tips going supersonic (hate it).

Charlie