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.

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