The ideal automatic controller would be a microprocessor that took
 all these factors into consideration to: A. first protect the engine
 from detonation B. the turbine from over speed while C. still maximizing
 the HP as the airplane climbed.

 Paul Lamar

Paul,

Great discussion, but I think you missed a couple important points.  Since
you and I are going to try out the stock turbo this loss in absolute pressure
is going to work in our favor.  We both acknowledge that the stock turbo is
undersized for the job and is going to be the limiting factor in making
power, with potential overspeed problems at altitude.  This spring and
diaphragm set up means that the 5 psi of boost pressure at sea level will be
maintained as you go up. While this means that the absolute manifold pressure
will drop as you climb, it is still always 5 psi higher than it would have
been N.A.  This is in contrast to an aircraft turbo that "normalizes" as you
go up, making the turbo work very very much harder.  IMHO, the stock turbo
would never be able to withstand this large increase in duty cycle at
altitude.  BTW, even though the absolute manifold pressure is dropping the
turbo is spinning faster just to make 5psi when at altitude.  IMHO,
diminished performance at altitude is the only hope for the stock turbo.

I don't see Greg Richter's set up as replacing the waste gate with a pop off
valve.  He replaced the waste gate with an exquisitely matched turbo for a
specific application.  If we ask him, I bet he will say that the pop off
valve rarely opens.  The turbo is matched perfectly (some might say
oversized) so that its peak full output only occurs at WOT.  I believe that
he regulates his absolute pressure just by using the throttle.  The pop off
valve is only for transient overpressures and a POV is recommended (by most)
with any turbo setup.

You are very right that the best way would be a computer.  But I'm not going
to hold my breath.  I'm already holding my breath for our prop project and
engine monitor and RV-6 engine mount :-).  Cudos to those of you working on
those projects, BTW.

Dave Leonard

Well you may have some good points there Dave. We will just have to wait 
until we have one flying and get the TIT and intake manifold pressure
and temp data. I am still waiting for TIT data from Greg but I did
not see a sensor on his exhaust manifold at OSH.

I thought a model airplane servo might make a good waste gate controller
with a computer.

Paul Lamar
 
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