I don't think boost is going to be our problem Dave. I am worried about
 over  speeding
 the turbine. I will implement a RPM sensor on the compressor side of some
  sort on mine.

 Also while you are inquiring please find out if there is a Inconel turbine
 wheel available
 that will fit the stock housing. Rumor has it the stock turbo can be
 retrofitted
 with TO3 parts. Obviously even TO4 compressor parts fit. One of my
 projects I have been meaning to get around to.

 The other big question mark in my mind is; will that small built in waste
 gate be adequate?
 I think boost will be the least of our problems. Not unless of course you
 are looking  for 700 HP :-)

 Paul Lamar

Paul, I agree that boost is not the issue and that overspeeding probably is.
However, I have been told, and it makes sense to me, that the best way to
control the speed of the turbo is to increase it's size, particularly the
compressor side.  This came from a long discussion of the subject with
turbonetics while I was at Oshkosh.

That is a bit of a surprise for me. I wonder how that is going to affect
the temperature of the turbine. My gut feeling is; it is going to load
it more and perhaps increase its temperature. Just a wild ass guess on
my part. I can see if you increase the size of the turbine you have 
more mass to absorb and dissipate heat and everything runs slower.
I could be way wrong on this. PL
 

I think you are right about the waste gate size as well.  Unfortunately,
there is not much room to port it and I have read about guys who overported
and could not get a good seal after that.  Its better to put on an external
waste gate for both efficiency and capacity, but that would require a custom
manifold and many dollars.  If you find a good optical tach that doesn't cost
too much let me know.  I would like to install one as well.

As far as other options and inconel turbines - I will have to ask.  I don't
get the impression that there are any other turbines that will fit the stock
housing (inconel or otherwise).  Apparently its not too tough to further
upgrade the compressor side.  For $700 we could get "any TO4E compressor
(larger than the 46 trim) in a housing that is attached via a billet
adapter."  This is part of the reason that I fear the 46 trim TO4E may not be
a significant improvement over the stock compressor.

Dave Leonard

 
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