I figured I'd throw this out here since I've been doing some research out of my own curiosity (Since I have free time but can't work on anything and it's driving me nuts)

http://www.area51machinedesign.com/rant_turbochargers

"A turbocharger with a good axial flow turbine can obtain pressure ratios as high as 3:1. (For every 1 psi (7 kPa) of exhaust pressure, the compressor is able to produce 3 psi (21 kPa) of air manifold pressure.) Turbochargers equipped with radial flow turbine have improved over time, but are nowhere near the axials. The Garrett T30 turbocharger (radial turbine) was designed in the 1950's and is only able to achieve a pressure ratio of about 1.5:1. The Garrett T18 turbocharger designed in the early 1970's is capable of a 1.7:1 pressure ratio with its radial flow turbine. "

http://books.google.com/books?id=ds19Bby_GSsC&pg=PA211&lpg=PA211&dq=mixed+flow+turbine+turbocharger&source=bl&ots=eYDiBBnWvM&sig=qItvzc8gMewVs1X6okt2qW-dgE8&hl=en&ei=-jyyTaK-JbC10QGg1sD6CA&sa=X&oi=book_result&ct=result&resnum=10&ved=0CFcQ6AEwCTgK#v=onepage&q=mixed%20flow%20turbine%20turbocharger&f=false

By reading these I am guessing that A)The boost to turbine PR should be lower than a conventional turbocarger B)I should have better boost threshold than a turbocharger with a similar turbine characteristics and a standard axial turbine?

 

Interesting. Too bad they're 10 times heavier and 10 times more expensive. I look at my S510 and remember it took two people to hang the sucker. Hang something that's 10 times heavier? Holy cow.

 

That's the full out axial turbines. The "mixed flow" turbines are sort of an intermediate turbine. They are some times called a "diagonal flow" turbine too from what I've been reading on them. The weight difference compared to a radial flow turbine is minimal. These turbos were/are actually made currently, I've got one on the way so I'm trying to find out more about them. The design is fairly interesting in its self.

 

After looking this up last night I decided to read enough of the journal article to become interested in it. Now I just have to find some spare time to look into it further.