Paul did Mistral ever get back to you about the turbo research they were
doing?
Could a turbo package be in the pipeline for individual sale?
What's the lightest firewall forward rotary package so far not
including Hatch's light weight engine.
Clifton.
I spoke to Mistral recently but did not ask.
I have the impression the turbo is on the back burner.
I think they are focused on getting the heavy fuel
NA rotary engine certified in Europe. In that case their
plate is quite full.
My guess is 300 pounds would be difficult to reduce
using cast iron intermediate and end housings.
Paul Lamar ...No rotor no motor.
Mistral is presently working on the turbo package. Turbocharged engines
could be delivered as early as next July, provided the turbo be
remote-mounted (as opposed to close-coupled "a la Mazda").
Next week, a most interesting experiment is scheduled. We have
acquired a
set of special paints that change colours in 40-50°F increments at
turbine
operating temperatures. We'll paint a couple of blades with the
appropriate
paints and run the engine at max power. After turbo disassembly, we'll
know
precisely what temperatures the blades are seeing and where the
possible hot
spots are. We'll then repeat the experiment at a couple of different
power
settings.
Should this experiment show that a close-coupled turbo can survive, than
this arrangement will be available end of year.
BTW, I'm interested to know what arrangement people prefer: turbo mounted
underneath the engine, in the "classic" way? Or close-coupled?
We do not know yet if we'll make the turbo assembly available separately.
Francois Badoux
Be careful mounting it under the engine. The oil drain back
from a turbo is a critical issue. Mazda and others have
had a lot of trouble with that. The turbo needs to be mounted
high enough so the oil (foam) can drain back into the oil
pan above the oil level. The 87-89 turbo had a drain back
problem. Mazda solved it in 90-91 with a larger shielded
drain back pipe.
Paul Lamar
Yes, Paul, you are correct. Actually, if you lower the stock Mazda
even as
little as 1/2'', the oil return doesn't work properly anymore and the
engine
starts smoking real bad. It is very sensitive indeed.
We are adding a third stage to our oil pump which will be dedicated to
scavenging the oil coming out of the turbo bearing and bringing it
back to
the sump.
Francois
That sounds like a very nice feature.
How is European certification coming?
Paul Lamar ...No rotor no motor.
Francois,
I think that if the turbine can be made to survive, the close coupled
arrangement is preferred because it makes the package more compact. I
think having it packaged tightly will ultimately lead to fewer
installation variations. We need to work toward limiting the variety of
installation decisions because as Paul has said many times "...the devil
is in the details..." and with every installation being unique, we have
trouble anticipating every problem.
I have decided to put the radiator between the engine and firewall
(canard, pusher configuration) to reserve the space under the engine for
the exhaust ejector and, if it needs to go there, the turbocharger.
Aubrey
I think the way to make the turbine survive is slow it down.
There are two equally important factors in turbine
life. RPM and heat. Dave Leonard slowed his down by
using a larger compressor. It showed all signs of living
before Dave had to go off to Iraq.
All three or four of the Mazda turbines that have failed so
far have been sized for automotive use. Turbines for automotive use
are designed for excess HP over and above that required
for steady state boost requirements. The reason this is
true is turbo charger RPM acceleration is everything in
a car. You want the turbo charger to accelerate as fast
as possible thereby getting the boost up as fast as possible.
That implies a overly high HP turbine. It also translates to an
over speeding turbine at steady boost numbers. Load down the
turbine with a larger compressor or a turbo compound gear box
and the turbine lives longer. Counter intuitive but true.
This also means that you need to monitor the turbine RPM as
well as the TIT.
Paul Lamar
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