Paul,

         What would be a safe top rpm for the 1989 stock turbo.  The do not
         exceed
         speed.
         Thanks
         Rino

         We don't know. My guess is around 100,000 +/- 10,000
         I am going on the TO4_60-1 compressor map.
         As I recall, Dave added the TO4_60-1 compressor shown in the
         second jpg to the stock turbo and it fit. This loaded down the
         turbine. It seems to be working so far.


         Paul Lamar ...No rotor no motor.



    Paul,
    I've been looking at several turbo maps over the last several days, and
    the one below is the one I keep coming back to.  The points I've plotted
    are based on both Gordon and David's spreadsheet.  The only moving
    variable for each point was altitude.  The first point was a SL and then
    every 3000 feet up to 15000.  I was trying to look at how the Turbo
    would react to fixed power settings but increasing altitude.  It looks
    like it spools up to about 100K RPM at 15K altitude.  This Garrett turbo
    is both oil and water cooled ball bearings, and the turbine is available
    in A/R of 0.85, 0.95, 1.06, and 1.19.  It doesn't say which turbine it
    comes, or which turbine is used to generate this compressor map.  If I
    used one of the large A/R turbines (a larger one than used to generate
    the map shown), which way would it shift the plotted line?  And would it
    slow the RPM by using a larger turbine?  If it slowed it a little and
    shifted it left a little, it would be even better.

    Don


    No attachment came across Don. A larger A/R should reduce the HP
    of the turbine and the back pressure on the engine. I am not sure it
    would shift the dotted line. I suspect it would just move the
    equilibrium
    point down to a lower RPM area. I am not sure and I will research that
    interesting question when I get back to the barn.

    I would definitely start with the 1.19 A/R and go from there.

    Paul Lamar ...No rotor no motor.


Ooops, sorry Paul !!  Try this........I pasted the pic below and
attached it as well.
Although I've seen a couple of turbo maps where my data plots more
midline, the reason I keep coming back to this map is because the turbo
itself is a oil and water cooled bearing system, so I thought it might
last longer.  I'm hoping that increasing the turbine A/R might shift the
plotted line slightly down and to the left, although if not, its
probably OK.  Notice that above 3000 ft altitude its running inside the
74-76% efficiency islands.  Also, with the ability to change the turbine
housing to various A/R's it lends itself to a little experimentation.
I'd hate to miscalculate which turbine
Is my engine at SNF this year?
Don

Yes that looks like it would work.

I am not at Sun n Fun yet Don. I am in San Marcos which is not far from Lockhart
and about 30 miles south of Austin on Hwy 35. I'll see Mark Stietle in a few
hours. This will be the last day I will be able to post until I get to Florida.

Paul Lamar ...No rotor no motor.

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