> >>> 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 :)
--
Paul Lamar ...No rotor no motor.
I think I understood you perfectly.. My point is that if opening a
valve to the turbo allows significant gas to flow through the turbo,
then there is excess restriction through the non-turbo leg of the
system. It would seem that if the non-turbo leg was very free flowing,
only a few psi would exist in the system. Opening a tap to the turbo
would only make a few psi available to drive the turbine for power recovery.
Matt-
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