Monty Roberts wrote:

Why reinvent the wheel? The model jet people have long since decided

the

best thing to do is place a magnetic washer under the compressor nut

and

place a sensor on the outside of the inlet.

See:

http://nades.net/catalog/index.php?cPath=22_25

Also note the thermocouple. You will of course have to devise your own
guage. I would use one of the new USB based data aquisition products.

You

could interface with a lap top. Or maybe a PDA. Not sure if they have

USB

ports or not.

See:

http://www.azeotech.com/products.php

Monty

Thanks for the turbo charger tach tip Monty. How far away is the sensor

from

the magnet?
I was just getting ready to design a water cooling system for the 75 C
plastic
fiber optics. We only need this thing for R&D. Once we have a handle
on the RPM we don't need it anymore.

Paul Lamar

François Badoux wrote:

We have the turbo RPM sensor which Monty talks about on both the bench
engine for R&D purposes, as well as on the Arrow for altitude testing.

I

don't remember the cost of the sensor, but the very fact I don't

remember

means that it is not very expensive.  It is easy to install and works

just

fine.

Francois--

What kind of RPM numbers are you seeing Francois?

Paul Lamar

On the original Mazda turbo, we see 105,000 RPM at max power (6,200 shaft
RPM, 42") at Geneva's elevation of 1,400'.  130,000 RPM at max continuous
power (6,200 RPM, 39-40") at around 10,000'.  As we don't have the Mazda
unit's chart, we have arbitrarily set the limit at 130,000 RPM.

Anyway, we are moving to a T04E-60 compressor which fits our needs almost
perfectly (we are "riding the crest" at 76-80% efficiency, slightly on the
"safe" side, away from the surge line).

Francois

Thanks Francois that is pretty close to what we are guessing at.
I think Dave Leonard is going with the same compressor wheel and housing.
It will be good to see the new performance data. If it works out I will
get mine modified as well :) Did you have to space the turbo out to
accommodate the larger compressor wheel?

Who modified the turbo for you?

Dave who did yours?

BTW Francois got any pictures of that mounted turbo tach circuit. I can't
quite
figure out how it is mounted from just looking at the pictures on the
Spanish manufactures web site.

Paul Lamar

Our chart is not exactly similar to the one you attached, although quite
close.  Is the fat black line where Dave's turbo is supposed to operate?
You don't want to get this close to the surge line.  Our calculated
performance line is "riding the crest of the hill" or erring a little bit on
the safe side.

I cannot send you pictures of the turbo RPM installation because we have the
N/A engine presently on the bench.  A turbo engine engine will go back on
the bench when the turbo is delivered, which should have happened 1-2 months
ago.  We are working with Kelly Aerospace/Turbonetics (Turbonetics belong to
Kelly...) but these guys are screwed up, they have more on their plate than
they can handle and the customer service suffers direly... and we wait, and
we wait...  We have a plan B and will activate it shortly if they don't
react shortly!

Francois

OK no problem. I'll just buy one and see what I can do about mounting it.
Thanks.

Too bad about Kelly Aerospace. Back when Turbonetics was privately owned
they were very responsive and helpful.

Paul Lamar
 
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