Message-ID: <01d801c379ad$c3b3a7e0$6401a8c0@office>
From: "Ernesto Sanchez" <res0391z@gte.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-2576865@logan.com>
Subject: Turbo selection
Date: Fri, 12 Sep 2003 21:16:10 -0700
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Snip:
>  That being said, has anyone
> come up with the real spec for the appropriate turbo, ie, T-what? turbine
> trim? compressor trim?  Lots of questions......
>
>        <marv>

 Please take everything I say with a grain of salt.  I'm not an expert by
any means but here's Paul Yaw (who builds and dyno's 13b turbo motors)
describing a rotary aircraft 13b turbo motor he built:

"The turbo (From Turbonetics) is a Garrett TO4E, 50 trim compressor, P trim
exhaust, with a modified 1.3 AR ratio housing. The turbine wheel is made of
inconel. The center section is water cooled. The turbo feeds the engine
through a small intercooler made by Spearco.
Boost is 6.4 psi at 6500 rpm. (43" Hg. manifold pressure.) Boost is
controlled by a Turbonetics "Deltagate"

End of quote.  Here is his web site:

http://personal.riverusers.com/~yawpower/ac13bt.html

Correct me if I'm wrong:  As we climb the air gets thinner so to get the
same psi we have to make more boost (pressure ratio goes up).   The Garrett
TO4E, 50 trim compressor (see compressor map) appears to more efficient
(less heat and less likely to knock or ping) as you climb and less likely to
over speed (explode).  The exhaust A/R Paul Yaw is using 1.3 (very big) and
he is an expert.  I think the 13b is different in that there is more
un-burned fuel in the exhaust and it's still burning (expanding) so you use
a larger A/R.  Also, I was told on this list that certified aircraft use
A/R's larger than 1.  Again with a larger A/R you are less likely to over
speed at altitude.  I'm not sure but I think I read an article in Contact
where Greg Rickter (sp) said his intake manifold (Turbo 13b Cozy) heat is
high and he is dumping allot of air.  His turbo may be on the small side but
again I'm not an expert.
Ernesto Sanchez