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Date: Sat, 26 Aug 2006 09:29:47 -0500
From: Charlie England <ceengland@bellsouth.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Exhaust heat (radiant energy)
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Lehanover@aol.com wrote:

> So here is an engine on the dyno at full song. Notice anything 
> interesting about the exhaust system? The engine is tuned for best 
> power, and that means just a hair rich of peak EGT.
>  
> It has a short life expectancy. Both the engine and the exhaust system.
>  
> These exhaust systems are .049" and .035" Inconel sheet stock rolled 
> and welded by hand. I have two of them. They are works of art.
>  
> Notice that the turbo must be supported. Even the Inconel has much 
> reduced strength in this situation.
>  
> At 900 HP and 28% efficiency how many BTUs are we looking at leaving 
> as waste heat?
>  
> So if you were to ceramic coat inside and out, and then heat wrap the 
> tubes the heat left in the exhaust gasses would be astounding. These 
> headers are exposed to the airstream in the race car. Not so in the 
> airplane. Even the tip of the exhaust pipe should be turned slightly 
> away from the airframe. The EGT measured at the port will diminish 
> only slightly at the tip of the pipe, if you insulate the pipe. You 
> cannot hold your hand even a foot from these pipes for even a few seconds.
>  
> Lynn E. Hanover


I love those cool (?) pics of engines running full bore.

Any thoughts on why the 1st 6-8" of the headers *aren't* glowing? Is the 
head sapping off that much heat from the headers? And if so, would some 
form of ceramic insulator between engine & header help keep exhaust heat 
out of the engine block?

Charlie