What if you find that even with the fully open wastegate hole, the TIT
and MAP is still too high at WOT?
If you have an old cracked turbo housing, you could try that on the
dyno with the flap removed.
Then a least you know if you are in the ball park.
A further option is to try and fit a smaller diameter turbine to the
existing stock shaft and housing.
What is Francois using in his turbo?
Erik
Well than if all else fails a hole in the turbine housing next to the
waste
gate will work as a last resort.
Francois uses the stock Mazda 1991 2nd gen turbo.
A larger turbine is what you need if you want less boost.
It also dissipates more heat because it is larger.
Paul Lamar
-----------------------
It is true that we use the stock turbo and will start testing it at
altitude (>7,500', max so far) after Oshkosh. Having said this, we are
90 % certain that we'll have to change it for the reasons already
mentioned in this thread. The compressor in particular is made to give
boost at low RPM and
ground level, the potential for overspeeding it at altitude and 6000 RPM
is great. The gap between the impeller and the compressor housing is
too small IMHO for an aircraft application. It results in overheating
the [charge] air, especially at mid-power settings: what do you think of 300°F
air discharge temperature at 28'' MAP but only 220°F at 39'' MAP? Seems
counter-intuitive, doesn't it? ... anyway, a good thing we have an
efficient intercooler...
Best regards,
Francois Badoux
That is interesting data Francois. The late stock Mazda sequential turbos
had abraidable compressor housings to improve the efficiency of the compressors.
I am sure glad you are monitoring all these parameters. Most of the guys
on here are reluctant or don't have the electronic knowledge to properly
instrument their setups. They are willing to fly it until it breaks however :)
Tom Parkes are you still flying without a intercooler? Are you monitoring
your intake manifold air temp?
Paul Lamar
The Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site. http://home.earthlink.net/~rotaryeng/
Copyright 1998-2004 All world wide rights reserved.