Paul,

 I just got through reading through John Slades website about
 his turbo troubles with different stock and Aussie modified
 Mitsubishi turbochargers.

 He as well as several other people recommend a Turbonetic
 TO4E -50 with the big shaft.  I know the unit  comes with
 an Inconel turbine, and P trim is recommended.  Since I want
 to turbo normalize the P-ported 13B at high altitude I have
 been advised that an A/R   around 1.15.  is best.  This way
 the turbine only makes a few inches on sea level take-offs
 but really pumps the air at low flight levels.   Do you know
 a purchasing source in California?  I am want to make sure
 I can order one with high nickel content and ceramic ball
 bearings as well.

 Doug in Japan

 Performance Turbochargers LLC
 8482 Cherry Ave.
 Fontana, CA 92335
 909-429-7200
 909-429-7204
 Garyhetrick@dieselusa.com
 www.dieselusa.com

 Limit Engineering
 885 Kiowa Ave.
 Lake Havasu City, AZ 86403
 928-453-7321
 928-453-0789 (fax)
 craig@redrivernet.com
 www.limitengineering.com

 Advanced Tuning Products
 28988 Hopkins St.
 Hayward, CA 94545
 510-445-1682
 510-445-1692 (fax)
 info@atpturbo.com
 www.atpturbo.com

 Retail Distributors
 Jim Wolf Technology
 212 Millar Avenue
 El Cajon, CA 92020
 619-442-0680
 619-579-8160(fax)
 www.jimwolftechnology.com


 You may have trouble buying a new TO4 as it is now obsolete.

 The A over R is a measure of how far the inlet diameter is
 restricted by the nozzle. An A over R over one means
 the inlet gas velocity is actually reduced before it is
 applied to the turbine.

 The high turbine A/R means it will not generate a lot of turbine HP but
 it will be less likely to over rev at high altitude. It will
 also have less back pressure on the engine.

 There are two A/R's numbers. One for the turbine and one for the
 compressor.

 http://www.turbobygarrett.com/turbobygarrett/tech_center/gt_basics.html

 "GT Basics / Nomenclature

 Please note that we have made
 a subtle modification to the GT nomenclature.

 In our product catalog, all offerings are grouped according to
 their turbine wheel frame size. The frame size of a turbo or CHRA
 is dictated by its turbine wheel inducer diameter . The larger
 the turbine inducer, the bigger the frame size-- so any turbo
 in the GT42 family has a larger turbine wheel inducer than
 those in the GT35 family, and so on.

 In the model name of each turbo or CHRA, you'll also notice two
 digits after the frame size. These two digits refer to the
 compressor exducer diameter, as measured in millimeters.

 Let's use the GT4294 as an example. This unit has a GT42 frame
 size turbine coupled to a 94mm (exducer diameter) compressor wheel.

 If there's an "R" on the end of a model name, this means the
 unit is ball bearing. So, a GT4294 is not ball bearing; whereas
 a GT4294R is ball bearing.

 The biggest change related to the nomenclature is this: units
 which utilize a 53mm turbine wheel (as measured at the inducer)
 are now referred to as "GT25" frame size, while units employing
 the slightly larger 53.85mm turbine wheel are now referred to
 as "GT28" frame size.

 For those familiar with our product range, this means that the
 unit formerly known as "the GT28R" (part number 466541-1) is
 now in the GT25R family. More specifically, it is now a GT2560R
 model."

 GTxxyyzz

 *  Positions "xx" refers to the frame size of the turbine wheel inducer.

  o For example the "GT28" in "GT2860RS" refers to its turbine wheel
 frame size family. All GT28 units use a turbine wheel with 53.85mm [2.12"]
 inducer diameter

  o As a rule of thumb, the larger the number, the larger the turbine wheel.


 * Positions "yy" designate the compressor wheel exducer (major) diameter
 in millimeters

 o The "60" in the GT2860RS example above has a 60mm compressor wheel
 exducer diameter.

 o Note: Wheel sizes 100mm and over omit the "1" (hundreds digit)

 o Example: the 02 in a GT4202 refers to its 102mm compressor
 wheel exducer diameter


 * Positions "zz" may be used to designate special features of a particular turbocharger where applicable

 o Example: GT2860RS

 o "R" = this is a Ball Bearing unit

 o "S" = used for units which require some differentiation
 from units in the same family Compare a GT2860R to a GT2860RS.
 While both are ball bearing and externally similar, the GT2860RS
 is better suited for higher-flow applications than the GT2860R.
 In this case, the S reflects the higher-flowing nature of the GT2860RS"

 End of Garrett quote.

 The 16 pound TO4 I have in my hand as we speak has a turbine inlet area
 diameter is roughly two inches in diameter. In the new terminology
 the inducers or diameter of the turbine wheel is roughly 3.5 inches
 or 90 mm.  It is not out of the housing so I am not sure of
 the exact dimensions. It could be a lot smaller. I'll take
 it apart shortly when I get time.

 The stock 1990 RX7 turbo weighs 22 pounds
 but it has a built in waste gate. The stock RX7 1990 turbine OD
 is 2.5 inches or 56 mm and compressor OD is 2.4 inches. Compressor
 ID is 1.72". This one I have out of the housing. This has been made
 to work in a modified form by Dave Leonard and others

 The exducer (small diameter of the turbine) size is 2.75
 inches in diameter or 70 mm. The turbine A/R is .96.

 MY guess is the TO4 turbine is about the same size as a GT4508 or a GT4708.
 I could be way wrong as the physical size is a bit bigger.
 The GT4508R has a water called bearing like the stock Mazda turbo
 and unlike the TO4 so that alone is a big positive. The R stands for
 ball bearing. The aerodynamics of these new models has been drastically
 improved so I would not be a bit surprised if the GT4508 was more
 efficient than the old TO4. One the other hand the turbine is small
 relative to the compressor so IMHO I don't think this is what you need.
 I would go with a larger turbine to actual reduce the heat load
 and the RPM on the turbine. The exhaust gas velocity and mass is
 a given so the larger the turbine the lower the RPM.

 Garrett uses a small diameter turbine to reduce the rotational inertia
 and improve the angular acceleration for automotive use. Not what
 a A/C application needs.

 The TO4  M-24 compressor has an inlet diameter of 2.5 and an outlet diameter
 of 1.95 and the marked A/R is .6.  The compressor wheel OD is roughly 2.5 inches
 in diameter and 1.75" small diameter. This size turbo is good for 700 HP
 so perhaps you need a higher A/R.

 http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_tech101.html
 http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_tech102.html
 http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_tech103.html

 Download the catalog and go from there.
 http://www.turbobygarrett.com/turbobygarrett/products/catalog.html

 What ever you do get one of the these turbo tachs and install it so you
 are sure you do not over rev the turbo charger as that is a sure
 fire way to have the turbine wheel fail at 1800 F inlet temp.

 Paul Lamar

 --



Paul,
Thanks for the long and detailed post.  Comparing
Turbonetics and Garretts is a difficult call for me. and I
have read all the Garretts stuff several times but I need
to speak with someone who has 'been there' flying with a
turbo 13B.  Personally I am not a fan of the modifying a
stock Mazda Mitubishi turbo to bring the rpms down.  Yes it
works but I think the newer high nickel content, ball
bearing turbo would be more reliable for long hauls.   I
believe John Slade, the Cozy Girls as well as Ross  ---? a
RV flyer were recommending the Turbonetics model I
described above. Why?  I dunno:)  John indicated he was
going to get one years ago but there are no updates on his
building log website to indicate he actually did it.  Do
you have a way I can contact him?



BTW  56mm equals  2.2"    1 inch equals 2.54"

Doug in Japan

John is/was mad at me for some reason. I designed a motor
mount for him and he had someone  weld it up but they took liberties with
my design and added their own ideas and totally screwed it up. I have
had that problem before with certain welders. Just make it
like the dwg. for @#$%^ sakes. For some strange reason some welders
think they are smarter than engineers :) Each line in the dwg was an
essentail tube and the welder left most out as he did not think them
necessary.  I chewed John out for not making it like the dwg and
demanded that he fix it so he got mad at me :) I just had his
safety in mind. I did not want the engine to fall off in the air.

He may also feel that I misled him by recommending the RX7 Turbo II
motor. At the time MecanAir, fore runner of Mistral,  was using the
RX7 Turbo II engine and I figured they had it working. It sure looked
well engineered and very compact. That was long before
we all found it it over revved at 12,000 feet and destroyed itself
in about 2 hours. Mecanair/Mistral went through three or so before
they revealed the problem to us.

So too John and Dave Leonard. I think John Slade was the first
to have it modified. The modified version does work but I am not sure the
modification are optimum. It took me a couple of years to figure
out why they failed. I called everybody I could find that was supposed
to be experts on turbo's and nobody could answer the simple question:
"How does one determine the HP of a turbine?" I tried to contact
a Garrett engineer that I had worked with 30 years ago on a turbo charged
Ford something or other. He had died or retired and I could not
find him.

The Effects of Turbocharger Design and Installation on
Gasoline Vehicle Transient Response.
David Elpern. Garrett Automotive Products Co.
SAE 821149   Use of the Lamar Instrument test
equipment to develop turbocharger design.

I even went to Foyles book store when I was in London looking for
books on turbines. I found a couple and bought them. As far as I
can tell Foyles is the best technical book store in the world.

http://www.foyles.co.uk/

The jury is still out on the RX7 Turbo II turbocharger as both Dave
Leonard and John Andrich are both flying essentially the same
thing. So too John Slade as far as I know but I have not heard
from him in years. Last I heard he moved from Florida to Connecticut.

Perhaps Dave Leonard knows how to get in touch with John Slade.

John Andrich is on here and his Turbo II powered Long EZ airplane
is in Camarillo so you may ask him and Dave questions.

BTW I think the TO4 is a dead end as Garrett has made some
significant improvements since then.

The owner of Turbonetics used to be very helpful on turbo's but he
sold out to Kelly Aerospace and the help evaporated.
As far as I can determine there is nobody at Kelly that
knows anything about it.


Paul Lamar