On a somewhat related note, has anyone seen Honeywell's dualboost turbos with axial turbines and dual compressors? They announced it a while back but just read about it today. Pretty cool tech.
Gasoline DualBoost Turbochargers | Light Vehicle Gasoline Engines | Our Technologies | Honeywell Turbo Technologies
http://turbo.honeywell.com/assets/pd...esentation.pdf
Apparently they're looking into incorporating VGT and TiAl too. But even in its "basic" form they're seeing a 50% inertia reduction and a significant movement of the peak efficiency to a lower blade speed ratio (~0.6 vs ~0.8) while keeping peak efficiency the same. Steady state performance is the same but they're seeing 50 more NM of torque 0.6s earlier on a 1.6L engine. The mixed flow turbine in the 7163 is a cross between this and the radial turbines we're used to. It would be reasonable to expect some of the same benefits Honeywell had with their axial turbine.
Awesome time for turbo tech right now
EDIT: Added one more compressor map overlay with a GTX3071 to the first post.