VATN Turbos

[ptimmerm@mashtun.JPL.NASA.GOV]

The variable area turbine nozzle (sic?) VATN, has a row of
small blades that are placed circumfrencially around the
outside of the spinning wheel.  The blades are moved in
unison to change the angle of attack of the air on the
spinning turbine, thus creating a variable A/R ration.
That is, conventional turbos have some fixed area to radius
ratio that is built in. You end up with a big, cool turbo,
or a small hot one.  The VATN gives the best of both worlds...
IF the vane controller knows what you want.  I am aware of
one installation on a street 323 with 250 HP, and if you lift
only once, it will come back in gangbusters, but life twice for
a shift or conrner and it bogs, cause the thing is confused.

I only know of Garret making these turbos, (besides the little
motorcycle units Corky talks about) but IHI or someone in 
Japan may also be making them.

Paul Timmerman