I finally found some info on this subject.
It is a bit crude as I expanded a larger chart.
A 2:1 pressure ratio would be about 15 psi
on this chart.

That means the HP required would be about
.05 HP per cubic foot per minute.
Since The turbo rotary needs about 250 cubic
feet per minute it looks like the HP needed
out of the turbine would be about 12.5 HP.

This is a ball park figure but the closest I
have come so far.

There are 11 turbine blades with a blade area of about
one square inches in the stock 2nd gen turbine.
Total blade area is then 11 square inches
or .076 square feet.

 At 600 MPH or 880 FPS
the a dynamic pressure is 936 pounds per square foot.
At a lift Coef. of 1 and an A/R of 1 tangential force on the blades
is .076 square feet times 936 #/sq.ft. or 71.5 pounds.
Radius is .75 inches roughly so torque is 95 inch
pounds. Zero RPM theoretical stall torque would then
be 95 inch pounds or  7.9 foot pounds.

At a wheel radius of .75 inches the circumference is
4.7 inches or .39 feet.

At zero torque RPM will be 880 FPS divided by
.39 feet or 2256 RPM.

Obviously this is way off so something is wrong
as we all know turbo's can run well over 100,000 RPM.

Check my arithmetic and logic.

Perhaps the gas is coming out of the engine faster
than I thought.

Paul Lamar