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From: "Rumburg, William" <william.rumburg@cdicorp.com>
To: "'lancair.list@olsusa.com'" <lancair.list@olsusa.com>
Subject: RE: exhaust backpressure
Date: Fri, 11 Aug 2000 18:02:07 -0400
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          <<  Lancair Builders' Mail List  >>
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>>
> I am wondering if the oval you are talking about could be the cut angle of
> the end of the exhaust pipe. 
> Scott
Hard to believe that could improve performance.  You have effectively
reduced the area through which the exhaust gases can exit.  That would
likely increase backpressure.
Matt
	Scott / Matt -
	I hadn't worked out the math, but yes, intuitively, I can see that
the pipe area is slightly reduced. However, if  memory serves me correctly,
the exhaust backpressure was reduced in spite of the area reduction. I
believe that is was just a phenomonea resulting from the shape of the
exhaust gas as it exited the tube. I won't post any more on this, unless I
can again find the information. Just thought someone might be knowledgeable
of this one way or the other.
	Bill Rumburg
	N403WR  (Sonic bOOm)
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