>>> Here's a link to a fairly long thread:
         >>>
         >>>

   http://canardaviationforum.dmt.net/showthread.php?t=2058&page=5&pp=15
   <http://canardaviationforum.dmt.net/showthread.php?t=2058&page=5&pp=15>
         >>>
         >>>
         >>>
         >>> I have no idea what is going on Matt. According to Francois
         >>> the unburned hydrocarbons are burning in the exhaust
         >>> manifold and or the turbo. Perhaps the RX8 engine might
         >>> be a better choice as it supposedly recycles unburned fuel
         >>> with a cooler exhaust. Francois is doing some turbine blade
         >>> temperature test by painting the turbine blades with special
         >>> paint.
         >>>
         >>> To really know what is going on the intake air temp should
         >>> be monitored and the engine leaned over a wide range
   measuring
         >>> the mixture ratio with a wide band mixture monitor to see
         >>> what effect this has on TIT. In other words get data on
         >>> TIT verses mixture ratio. Could be when leaned properly
         >>> with a a cool intake charge to discourage detonation or
         >>> even anti detonation fluid injected the data
         >>> will show the TIT coming down with a leaned mixture.
         >>>
         >>> On the other hand 1800 F may be no problem for an Inconel
         >>> turbine at modest RPMs. Does John have an Inconel turbine?
         >>> One needs to know the RPM of the turbine as that has a
   serious
         >>> affect on the life of a turbine blade due to centrifugal
   force.
         >>>
         >>> Paul Lamar ...No rotor no motor.
         >>
         >>
         >>
         >> Hi Matt, where's your EGT probe mounted?
         >>
         >> B
         >
         > Brian, according to John's post about this turbo, about which
        Matt was
         > questioning, John's EGT probe is mounted in the exhaust pipe 2
        inches
         > after
         > the turbine.
         >
         > Barry Gardner
         > Wheaton, IL



        1700*F at 2-3" past the turbine housing is far, far too hot.
   Just to
        give
        you guys
        an idea of what I do, I shoot for mid 1400's and nothing higher
   on very
        heavy
        loads that go into the several hundreds of horsepower range. My
   next
        question:

        What kind of manifold pressure are you running on take-off
   John? At that
        manifold pressure, what's the amount of advance you're cranking out
        of the
        computer for the leading plugs and then the trail-split timing
   advance?

        Also, do you guys monitor air/fuel ratios using a 5V wideband
   lambda
        sensor
        setup?

        B

   ___________________________________________________________________________
        Brian D. Cain -/- Dallas/Ft. Worth, TX -/-
   bdc@bdcmotorsports.com <mailto:bdc@bdcmotorsports.com>
        BDC Motorsports | Performance Rotary Engines, Specialized
   Porting, EFI
        System Installation & Tuning
        MSN bdc196@hotmail.com <mailto:bdc196@hotmail.com>, Yahoo!
   bdc196, AOL Symajhi, ICQ# 1733105
        http://www.bdcmotorsports.com -/- http://bdc.cyberosity.com


If this turns into a really tough problem...

Is there any chance that an _axial_ flow turbine could be designed such
that a portion of the wheel (like half to 2/3rd) is blown with hot
exhaust, but the remaining portion draws cool air?  It might be possible
to significantly reduce the average temperature that the wheel sees this
way.  One downside of this arrangement is that the wheel will see very
assymetrical loads - the side exposed to the exhaust would be forced one
direction, but the side pulling cool air would be forced the opposite
direction.  I suppose that if you feed cool air in on two sides of the
wheel, the forces could be balanced..

Or how about cool air injection?  It would have to be fairly high
pressure - a good trick, cool, high pressure air.  But it only has to be
relatively cool - to lower the temp of the wheel.

A plot of EGT vs ignition advance vs mixture would be interesting.  More
stuff to do on a dyno.


Regards,

Matt-

Well it turns out there is slight advantage to an axial
flow turbine from an eff. point of view in this size range.
However it is possible to build them with hollow blades and
cool them from the inside. The main problem is $$$$ bucks.
No advantage to a lower BSFC if you have to pay up front
big $$$$ bucks for the lower BSFC. A good example is the hybrid
car.

It is easier to cool the exhaust slightly by moving
the turbine down stream as done in the P47 and as Francois
is proposing. However I am still not convinced the heat
is an insurmountable problem. IMHO the main problem
so far has been the excessive RPM

Paul Lamar ...No rotor no motor.

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