George,

Thanks for your interest in my post/questions.  I was told the standard
TSIO-550E turbos (A/R=0.5) were "sized" assuming the bleed air sonic nozzles
are in place.  Without them, the tubro surges and runs the risk of a
momentary overboost and/or compressor stall (personally unverified).

My understanding is that the job of the pressure controller and waste gate
is to prevent that.  However, perhaps the dynamic response is inadequate
and/or turbine rotational inertia too great and... overboost.

Seems that several folks have swapped the std turbos for some with a
"looser"/larger turbine throat (A/R = 1.0 or 2.0), which would decrease the
turbo responsiveness, and have thus been successful in plugging the bleed
air nozzles (which are otherwise an efficiency loss if left open in an
un-pressurized aircraft).

I'm trying to gather info to separate OWT from actual experiences.  If it
seems to work, I'll do the same on my un-pressurized Lancair ES (TSIO-550),
currently under construction.

Any/all insights are welcome (especially from you!)

Rick Titsworth
rtitsworth@mindsoring.com
313-506-5604



-----Original Message-----
From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of
Marvin Kaye
Sent: Monday, April 17, 2006 10:41 PM
To: Lancair Mailing List
Subject: [LML] Re: TSIO-550 Turbo setup for non-pressurizedLlancairs -
Pictures

Posted for "George Braly" <gwbraly@gami.com>:

  
  Richard,
   
  Why do you think that the  plugged sonic nozzles are "ill-advised"  ?
  
   George Braly
  
  

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