>>> You will not necessarily get more boost with a larger compressor.
     >>> What it does is load the turbine down so it does not spin
     >>> as fast. The high speed spin is the main reason they fail.
     >>> Temperature has a lot to do with it as well but in our
     >>> case it is mostly spin IMHO.
     >>>
     >>> By all means cutting the turbine blades
     >>> sounds like a workable plan. Let us know how it goes.
     >>> Would be nice if you added a turbine tachometer
     >>> so we could get a better handle on the problem.
     >>>
     >>> Paul Lamar ...No rotor no motor.
     >>
     >>
     >> Paul,
     >>
     >> I have a fuel injected, single turbo 13b sitting in my hanger
    (`86-`89
     >> model with intercooler). I have heard from several sources that
    the stock
     >> turbo is not the best to use in aircraft application because of
    blade
     >> disintegration, over speeding, etc.
     >>
     >> What turbo should I use? Exact name and part number, please, so
    I can go
     >> to the turbo shop and ask for it by name. I do not know yet into
    what
     >> plane the motor will go into, but a 2.17:1 reduction will be used.
     >> Probably Tracy`s with his ignition and engine controller.
     >>
     >> Thank you and regards,
     >>
     >> Erik Snyman
     >> Messina
     >> South Africa.
     >>
     >> I don't know. We have not had enough guys run other than stock
     >> turbo's to really know what lives. We do know the stock turbo
     >> will live if a larger compressor is fitted. Tom Parkes has run
     >> an old aircraft turbo on a 3 rotor for awhile and that seems to
     >> work. Unfortunately it is out of production as I recall.
     >>
     >> Tracy's EFI will still have to be individually tuned for your
     >> specific airplane and engine. Also I would suggest an intake
     >> manifold air temperature alarm or sensor that detected intake
     >> manifold temperatures  over 140 F. It would be ideal if
     >> it richened the mixture or retarded the ignition slightly
     >> in that case to avoid detonation.
     >>
     >> Paul Lamar ...No rotor no motor.
     >
     > Paul,
     > I still feel (especially in stock turbo use), the bypass idea is
    the best
     > way to reduce heat and overspinning of the turbo. My new Suzuki
    motorcycle
     > has a butterfly valve to vary back pressure ( at different RPM's) for
     > exhaust tuning - the same principle can be used for the bypass to the
     > turbo.
     > Claiming original idea and patent rights.
     > George (down under)
     >
     > The stock 2nd gen  turbo already has a waste gate bypass valve.
     > Nobody (other than a car racer wall grind jpgs), to my
     > knowledge, has effectively ported it to increase
     > its effectiveness so far. In theory it should work.
     > As I recall Dave Leonard removed the flapper entirely
     > but that did not seem to work well enough. Apparently the
     > hole must be greatly enlarged. The flapper is also
     > restricted from opening 90 degrees by the back cover without
     > modification. Some of those mods are shown here
     >
     > Are you advocating adding a restrictor after the turbine?
     > If so that in effect is what happens with the stock exhaust
     > system in the 2nd gen RX7s. As soon as you remove the stock
     > exhaust system the boost jumps up several psi.
     >
     > Paul Lamar ...No rotor no motor.

    Paul,
    I'm suggesting a restrictor before the turbo and having the turbo in
    the
    bypass. In actual fact the turbo will not see any exhaust until it's
    wanted/
    needed and even then it is restricted.
    In a car turbo the turbo see all of the heat and power of the
    exhaust and
    the wategate allows some to bypass - as you suggest not sufficient.

    The idea is to isolate the turbo from heat and power (overspinning)
    and only
    allow the minimum requirement for the job at hand. OF course
    overspinning
    still might be a problem if a lot of turbo is required at very high
    altitudes, but my feelings are that this is not the requirement of most
    turbo applications i.e. turbo normalizing!
    George (down under)



This is probably an issue of semantics, but restrictions should
generally be avoided.  They waste energy.  Airplanes don't have energy
to waste.

Size the path around the turbo to provide enough bypass to keep the flow
through the turbine below a limit value.  Said differently, the only
restriction in the side with the turbo should be the turbo.


Regards,

Matt-

Matt,
The restriction ( Butterfly) is to the Turbo - it doesn't consume any energy
rather redirects to exhaust or Turbo to the percent required!
George ( down under)

You will just have to learn 3D George :)