R c wrote:

I understand that the turbo?s used for aircraft applications should

have a

inconel wheel.  Does anyone know which turbo make and model is

commonly

being used for turbo 13b and 20b aircraft applications.  Any idea on

the

pricing of these units?

Last time a checked an Air Research TO4 with Inconel wheel from
Turbonetics was $750. See the ACRE NL web site for the Turbonetics
URL. I think Chuck has one on his three rotor as I recall. Right
Chuck?

Paul Lamar

How long until a turbo needs rebuilding & what exactly needs replacing
?

Rich

Good question. I have no answers yet. I imagine it depends on what
temperature you run it at. I would opt for water cooled bearings
as they seem to help.

Paul Lamar

charles.harbert wrote:

To Rc:

You may want to get the std books for Turbocharging (Hugh McInness(HP

Books &

Corky Bell's) to learn exactly what you'll need to do this correctly.

Talk to

Ola at Turbonetics as he knows aircraft applications. I do have a T04, but

it's

beem modified by Turbonetics.

The turbo should last indefinitely provided you don't do the usual mistakes:

1. Overheat the wheel (Mazda's can do this easily because of the basic

design)

1700 degF TIT (turbine inlet temp)is max or you'll start eroding the Inconel
wheel. Temp is a function of air fuel ratio and boost. You also need to

direct

airflow around the turbo, plus use heat shields to insulate it from the

aircraft

and engine parts i.e. intake manifold, wiring, etc.

2. Inadequate oil flow - With this kind of heat in the turbo you need to

get a

good flow into the unit, and (most important), you must get it out the drain
without restriction (I use a scavenge pump).

3. Clean Air- Turbos spin up to 100+K rpms, so you don't want anything

of any

size going into the compressor.

4. Overreving-If you fly at higher altitudes, you must not exceed the

limit for

compressor ratio, or the unit could self destruct.

Hope this helps.

Perhaps the biggest and most common mistake was omitted.
5) Cool down: The turbo and manifold MUST be cooled down prior to shutdown.
 Failure to do so will roast the oil that is stagnant in the bearings
leading to deposits and premature bearing failure.

Jeff Spitzer

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