Paul,
I believe this turbo, the Garrett GT-2860R with the 76 trim and optional
0.86 A/R housing might be just what we are looking for in our aviation
uses. I`m considering it as the turbine for the turbocompound test
engine use but perhaps it might be a good choice for Dave`s plane as
well.
The bigger A/R will slow the wheel down but provide more torque at higher
rpms.
The high content Ni body and Inconel turbine wheel will handle the heat
better than the standard IHI turbochargers from Mazda which are, lets
face it, 20 year old technology. The Garrett in addition has ball
bearings, is compact, has a built in waste gate and has both water and
oil cooled jackets. Whats not to love? Beside the price we will have
to drill the threads out of the holes. I don`t know if the lack of a
split turbine mouth will an issue I imagine it depends on the exhaust
manifold design.
No info on weight unfortunately.
http://www.turbobygarrett.com/turbobygarrett/catelog/Turbochargers/GT28/GT2860R_707160_5.htm
Doug in Japan
I'll study it Doug. And get back to everybody on it. .86 A/R is not all that big.
Could be bigger. I have seen them with over one. If it is a automotive turbo
there is excess HP built in to accelerate. We are going to need an unusual
combination. Might be OK for turbo compound as the engine will slow the turbine.
-----------------------------------------------------------------------------
A quick thought.
Lets separate turbo compounding from turbo charger for the moment.
For turbo charger the diverted valve manifold and turbo tach is the way to go as
you can use any turbo charger. You set a turbo RPM redline and the diverter
takes care of holding that. Manual or automatic. Boost is whatever you get
at that turbo RPM. If you are feeling rich you can up the turbo RPM red line
and risk a turbine failure.
Apparently what we have gathered so far is there is so much kinetic energy in the
rotary exhaust it tends to ignore more or less built in waste gates.
Got to run. Be back later today.
--
Paul Lamar ...No rotor no motor.
Paul,
Yes, in the GT 3482R series they come without a waste gate, and two
options for the exhaust pipe mounting. Unfortunately they don`t mention
a Inconel turbine as an option. This model is recommended for engine
displacements from 2000 to 6000 cc. One option has an turbine A/R of
1.06. Turbine wheels are all 68.0mm dia. and 84 trim. I definitely
agree with you that we need larger wastegates so that when flying we can
isolate the turbine completely. Whether that mean enlarging the waste
gate hole on the built-in models, making a complete prior by-pass system
as you have shown or a combination of the two.
BTW, I made a Rhino drawing of the spin muffler turbo mount system,
saved it as JPEG file and now I can`t find it in the computer. Hmmmm?
Doug in Japan
Not a waste gate. A motor controlled diverter valve.
Once you have that device you can experiment with turbo's until
we find one that gives the most boost and still lives.
Turbine 101.
Peak turbine torque occurs at zero-RPM.
Zero torque occurs at max no-load-RPM.
Max HP occurs at .5 X max no-load-RPM.
All RPM's are the turbine RPM. Not the engine RPM.
Boost will be proportional to turbine HP.
1) Given a constant R or turbine diameter and a given
exhaust gas flow volume.
Larger A:
Lower exhaust gas velocity.
Lower peak torque.
Lower max no-load-RPM.
Lower max turbine HP.
Lower back pressure on engine.
2) Given a constant A and variable turbine diameter and a given
exhaust gas flow volume.
Larger R:
Same exhaust gas velocity.
Higher peak torque due to longer moment arm.
Lower max no-load-RPM due to longer moment arm and
circumferential velocity being the same.
The same max turbine HP ????. Higher torque lower RPM.
(Better for our purposes?)
Same back pressure on engine.
The key to figuring out what is going on is turbine diameter
>>>> AND <<<< A/R. These are the critical parameters as far as
turbine HP is concerned.
Next question? HP consumed (required) and boost as a function of
compressor diameter and A/R.
Paul Lamar ...No rotor no motor.
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