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Date: Sat, 30 Apr 2005 22:06:39 -0500
From: Charlie England <ceengland@bellsouth.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Inserts
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Tracy Crook wrote:

> I did say that I found no significant difference BUT, that was based 
> on two different engines with two different intake configurations.  
> The splitters were in a 6 port engine (normal) and the turbo ports 
> were in a 4 port.  This was also with an  -A drive (2.176 : 1)   where 
> the rpm was held lower.  I agree with Ed that the turbo ports may make 
> a bigger difference at higher rpm. 
>  
> In summary, there were too many variables involved to make any hard 
> declarations about the effect of exhaust ports alone.   But the effect 
> on noise was obvious  - The turbos are MUCH louder.   If I had it to 
> do over, I would have put splitters in my 20B.  I really like quiet 
> flying  (quiet being a relative word).
>  
> Tracy  (doing dreaded fiberglass stuff on the RV-8)


Not directly applicable here except in the sense that we should make no 
untested assumptions, but here goes:

Kent Paser of 'Speed with Economy' fame played with 'reversion cones' on 
his Lyc. They are cones smaller in diameter than the exhaust ports & 
mounted directly in the ports. Obviously this should interfere with 
exhaust flow but he found that they can improve breathing in a Lyc.

The NA splitters look suspiciously like flattened cones....

To invert Bob's tag line: when things change, things change.

Charlie
(just stirring the pot a little)