>
>> 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.
Seems like adding a bigger compressor works, but it effectively
increases backpressure. On the engines where the larger compressor is
adapted, have people found that the same MP can be generated at a
reduced throttle setting (larger intake restriction) as compared with
the smaller turbo? A thermodynamic sacrifice?
I would guess that removing the stock exhaust on an RX-7 has a
detrimental effect on turbo life - allows the turbo to spin faster?
As has been discussed here before, the exhaust stream at high power
settings on the rotary has LOTs of energy in it. Plenty to
turbo-normalize to a very high altitude. That's why the turbo-compound
is a must-do.
If you just want to turbo-normalize, the stock turbocharger size might
be fine, but a big bypass is in order.
Matt-
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