Hey Paul,

   Does the dyno data that you've seen for the 13B include EGT (pyrometer)
   information?  That data seems like it would be part of the common suite
   for dynos.  How about for the P-Port that you were running last year
   (finally on carbs)?


   Regards,

   Matt-

   We have the data around somewhere.
   OK here is some but the EFI mixture is far from set up right.
   The BSFC is all over the map. We never did get Tracy's
   EFI working well on the dyno.
   --
   Paul Lamar ...No rotor no motor.


Thanks Paul,

That's pretty toasty.  Think it would go to 1800F with the fuel turned
up even more, or is ~1727F the peak?  Seems like it tracks pretty well
with RPM (which is not a surprise).  8000RPM could be hotter.

I am still wondering about turbo life, and what John Slade reported
about his EGT's and what Mike Busch says about operating turbocharged
big bore Continentals.  Namely this quote from the following article:

"Another high-altitude problem is that you may exceed the turbocharger's
turbine inlet temperature (TIT) limit before reaching peak EGT. Cessna
did not install TIT gages in most of its turbocharged airplanes, but
many have after market gages (like GEMs or JPI 700s) with a TIT readout.
Published TIT red line is usually 1650°F but for optimum turbocharger and
exhaust system life, it's a good idea to limit TIT to 1600°F or less. If
your TIT is higher than that, you can either reduce cruise power or run
richer; I'd recommend the former."

http://www.avweb.com/news/airman/184350-1.html

Brainstorming ways to improve turbo durability..  In 1982, our
turbocharged Volvo (gasoline) - 245GLT was delivered with a turbocharger
that lacked "water cooling".  That turbo system would run less than 50k
miles before the seals leaked oil so badly that the catalytic converter
was plugged and the engine would choke out.  After replacing the turbo
the 2nd time, my dad did some research and found that Volvo had changed
the turbo system in 1984(?) to include "water cooling".  We got a
retrofit system to add "water cooling", and it seems that the turbos now
last more than 100k miles, though in hot weather city driving the car
consumes some water.  At shut down on a hot day the car sits and gurgles
for a few minutes.  It's possible we need to replace the pressure tank
cap (maybe leaking and boiling are caused by lower than optimum system
pressure).

Standard aircraft engines don't have an easy way to include water
cooling on the turbo, but with a rotary, maybe it would be easier to
include...  Does anyone know what part of the turbo is water cooled on
some automotive applications?  I am fairly certain the Volvo uses an off
the shelf Garret turbocharger.

I understand that the likely near term problem with the existing
turbocharged rotary aircraft has been over speeding.  Getting the right
size wheels/housings (and/or turbo compounding) will fix that, but
keeping the components cooler should also help, though doing so hurts
thermodynamic efficiency.  A trade off should be possible.

I also haven't given up on the idea of pre-turbine water injection for
limited time high power operations.  This could greatly lower the
temperature of the turbo.  At the same time it could hugely increase the
exhaust volume, which could mean improved turbo compound output.

Finally, I think I remember you saying that the Mazda will run happily
at more than 100 deg LOP EGT (maybe 200 deg?).  How about under boost?
Are detonation margins driven solely by inlet temperatures - so LOP with
boost is okay as long as the intake is cool.  Peak power EGT (75 deg
ROP) under boost might be the hardest to handle...

So, turbo life can be improved by selecting correctly sized components,
limiting operations at peak EGT to short periods of time (possibly while
running water injection), plus possibly through water cooling of parts
of the turbo.  Sound right?


Regards,

Matt-

The stock Mazda turbo charger are water cooled.

I think some of that excess rich mixture is burning in the exhaust
manifold. The side exhaust port engines recycle much of it and the
temperature drops a couple of hundred F. Turbo life of course
is a function of both temperature and turbine RPM.

I am thinking a thermopile made of a sandwiches of rings
of dissimulators metal separated by a ceramic insulators
will take some of the heat out of the exhaust with out wasting
the energy contained therein.

The jury is still out on how lean we can run it under boost.
Dave Leonard probably knows more about that than anyone
right at the moment.