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

Don Dunbar wrote:

Hi all,
I will join this descussion on turbine control and add my 20 cents worth.
I have a very good friend who is the Motec EMS installer and programer at
his performance workshop, West Racing. The Motec unit can monitor turbine
speed and control it with the exhaust waste gate, it can also control
exhaust tempreture via fuel injection. This unit you can programe to give
what ever power you require for any altitude. It has a nice cockpit logger
which will eliminate some of the monitoring standard equipment.
Go to www.motec.com.au these inits are made in Australia and are used in
most race car here and in Europe, they are bullet proof as they say in
racing circles. I am using one of these in my insterlation and maybe a
cheaper version  as backup. As the main control processor unit is only
$1000.00 US I may just duplicate the system.
Regards Don

 
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