Hi Dave Leonard,

 Did you do your own turbo upgrade to the TO4 big shaft wheel, with
 the  TO4E 50-trim compressor? Where did you buy the parts?

 Paul Lamar


 Yes, Paul,

 BNR Supercars did the mods to the stock turbo housing.  Google
 them.  I
 did the stage 4 upgrade, but selected a high pressure (instead of high
 flow) compressor (they can install just about any TO4 compressor you
 want.).


 --
 David Leonard

 Turbo Rotary RV-6 N4VY
 http://N4VY.RotaryRoster.net
 http://RotaryRoster.net


 Where did you buy the parts for stage 4 upgrade high pressure
 compressor?
 Do you have the maps for both? I think I have your earlier map.

 Paul Lamar



 I just sent my turbo to BNR and they did all the work and supplied the
 parts... boring out the housing, enlarging the waste-gate, making

 everything fit, balance turbine and compressor...  Cost about 1 AMU.

 I looked up the maps on the internet, easy search.  To be honest, I
 cant
 say for sure which compressor I have right now...  but I think it is
 the
 to4-e 50trim...  Garrett has a page with all the compressor maps.

 --
 David Leonard

 Turbo Rotary RV-6 N4VY
 http://N4VY.RotaryRoster.net
 http://RotaryRoster.net


 I spoke to Bryan on the phone. He did not seem to grasp
 the problem we are having. He kept talking engine HP.
 That is the least of our worries :) I got the impression
 he had never installed a tach.

 Paul Lamar

 Dave, do I have a deal for you. We are about to do a tach
 install on Michael's turbo. My next door hangar neighbor Jim Poole
 is an excellent machinist. It takes most of the time
 setting up the compressor housing on the mill.
 If you buy a tach kit we will do yours at the same
 time. All you have to do is unbolt the compressor housing
 and send it to me.

 I am certain if you keep the turbo RPM below 80,000 RPM
 at all altitudes you will not blow up another turbo.



 Paul Lamar


 You are right about Bryan, he does not really get our application.  I
 had to basically make him put in the to4e instead of the v-trim.
 But he
 does a good job once you tell him what you want.  There are other good
 turbo guys out there, but he is the only one I found (besides the guys
 in Auz that John Slade used) that can put a TO4 into the stock
 housing.

 If you want to keep the RPM under 80k at ALL altitudes and power
 settings, you will probably have to go to a different class of turbo
 all
 together, something larger than the TO4 stuff.  Or maybe sequentials.
 80k is a pretty low number  Once you get above a P/R of about 1.6 all
 the map I have seen will be above 80k, let alone the worst-case 2.5
 P/R
 that I expect.

 Unfortunately, like I have said.  To remove the compressor housing, I
 have to remove the whole turbo, exhaust, coolant and oil lines, drain
 the coolant etc...I'm just not interested in the extra work.  Cause
 no matter what the tach says, I'm going to keep doing the same thing I
 am now.  (keeping EGT under 590C, and on the rich side if I am using
 any
 significant amount of boost).

 Sorry.


 --
 David Leonard

 Turbo Rotary RV-6 N4VY
 http://N4VY.RotaryRoster.net
 http://RotaryRoster.net

 Maybe I am misunderstanding pressure ratio.

 60 inches of HG sounds like a P/R of 2.

 That means 400 HP I think.

 What am I missing?

 Pressure Ratio defined: Garrett.

 * Pressure Ratio is defined as the Absolute
 outlet pressure divided by the Absolute inlet pressure.
 http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_tech103.html

 Why would you need more than about 1.5 ?

 or 45" Hg.

 My guess is find a compressor that puts out 1.5 P/R
 at less than 80K.

 BTW 590C is 1100 F. Rich as the ocean :)

 Do the tach when BNR sends it back.
 We have about a month.

 I'll take off just the compressor housing today
 on the mock up to see what is needed to be removed.
 I can see your coolant line would be a problem.


 Paul Lamar


 Gents,
 A few things to ponder:
 1. What makes turbos come apart is more commonly abusive transient
 operation, wheel resonance (fixed to design), poor balance (not an
 issue
 with OEM turbos), and too high temperatures. You can over speed the
 wheels to be sure, but 80krpm is quite conservative for a wheel the
 size
 we would think of for a 2 rotor, especially at altitude. The
 compressor
 maps are a good indicator of this. The OEM has mapped the compressor
 performance on the above T04B to 126.3krpm, rest assured the impeller
 can tolerate this speed in steady state. What will fatigue the wheel
 is
 running up to max speed and back down to low speed in transient, think
 race car or city bus. An aircraft however is mostly steady state
 operation, which is why turbo-machines work so well, and reciprocating
 machines often fair poorly. Turbine wheels are much more robust than
 impellers (Inconel vs. Al) and characteristically have a higher speed
 limit, so the impeller is your limiting factor.

 2. A turbo tach. is a fantastic tool for validating a new turbo
 application no doubt. However, once the match is done one can quite
 accurately predict turbo speed based on the compressor map. If you
 know
 X & Y, then Z is defined by the compressor map. It will be more
 difficult without the raw map data to be sure.

 3. The two most common methods for measuring turbo speed are using a
 flat milled onto the turbine shaft and the sensor tapped into the
 bearing housing, or a blade pass sensor tapped into the compressor
 cover. The blade pass sensor is more accurate (much better
 resolution),
 but more "difficult" to install as it requires some precision in
 placing
 the sensor on the profile. It is also less robust for a permanent
 installation.

 4. Aftermarket turbo "up-fitters" make me nervous. I highly doubt
 their
 ability to balance a rotor assembly to anywhere near the precision
 even
 mass production turbo OEMs achieve. I just would not trust my safety
 to
 one. Maybe not so bad if they are just fitting a NEW component
 balanced
 rotor system, but whenever there is "trimming" involved that is not
 done
 by the OEM I get nervous. A good balance machine is not cheap, and
 from
 personal experience the after market for turbos is a scary place.
 There
 is good reason most re-manufactured turbos only come with a 1 year
 warranty. OK for a car, not OK for an aircraft IMO.

 Cheers,
 Zach Knutson


So for the barely initiated onlookers like me....
what modifications need to be made to the stock
Mazda turbo for aircraft use?  Thanks again.

Gene Kahn

The jury is still out. Dave Leonard is still in the trial
and error mode.

My guess is keep it under 80,000 RPM until further
notice :) That means a turbo tach is essential.

IMHO that is your best bet.

Porting the built in waste gate will help.
Disconnect the auto boost controller and connect
up a push pull cable and leave it open most
of the time. If it is well under 80,000 RPM
at 12,000 feet you can close the gate to get
up to 80,000 RPM. After that RPM you may be on thin
ice :)

A 1/2 inch thick steel spacer under the back cover
will allow the waste gate to open more.

I suggest you do a good job streamlining the internal
plumbing and inter cooler aerodynamics which reduces the back
pressure on the engine for a given boost.

Paul Lamar