Although the T3 compressors are a good match the turbines are WAAYY too
small which is why most people use the T4 series.  Even with a "P"
trim T4
and big A/R you still have to wastegate a bunch.  The weight difference
isn't too bad.
Jeff Spitzer

The only compressor maps I have right now are for the ones from
Turbonetics off their
website.  Is the T4 series you mention the Turbonetics T04B's and -E's, or
are they the Garrett T4's?

Scott

Pretty much the same.

Paul Lamar

Jeff Spitzer wrote:

The T04B is the standard.  The T04E is the latest design and is more
efficient so they charge more for 'em.

Jeff Spitzer

Here is an idea that might save some money and weight. Use a stock turbo
or a TO3 and put a Inconel butterfly valve down stream from the turbine
exhaust. This could add some back pressure at high altitude and prevent
the turbine from over speeding. So far I cannot think of any downsides
other than reduced boost and HP but I am sure someone will. The exhaust is 
cooler on the outlet side of the turbine so the heat environment is 
not quite so bad as it is upstream.

BTW I am in the process of researching a fiber optic tach for
the turbo RPM. I will feed the fiber optic cable down the exhaust
pipe of the compressor to look at the compressor blades and count
them as they go by with a high speed photo diode I hope.

Paul Lamar
 
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