[gumby79]

Originally Posted by Xist

I think someone mentioned this idea recently and the answer is that turbos spin far faster than alternators, so much so that it would not work.

Not true any more.
Brushless DC Motors, Servo Motors, DC Motors, Permenant Magnet AC Motors, AC Servo Motors, Permanent Magnet Synchronous Motors, High Speed Motors, Custom Motors, Gearheads, Encoders, Motion Control, Slotless Motors, Sensorless, Ironless Motors, Vacuu
has this

http://www.koford.com/Generators.pdf[/COLOR]
This is rated up to 400,000 rpm

If you use a waste gate housing you can regulat the shaft Speed. Or even better a VGT (Verible Geometry Turbine )

"Oil pan 4 Those step down gear boxes are expensive and the ones I know of are only approved for 40,000 to 50,000 RPM. Most are only used for around half of that.

This system would be so expensive there wouldn't be any point."

With the gen set parts in the link, the need for a gear box removed ,is this posable?
As for expensive all R&D is. The key is to use off the shelf parts.

My thoughts add 2nd turbocharger ,my rig already has1. Maby a vgt turbo link . Replace the impeller (as it is the thrust bearing pre load) with a spacer and direct cupple the BLDC400, 000 rpm motor/gen to the shaft.
The reason for wanting this not to be in my Intake sys., is simple. Any failure bits and pices would go through the engine, resulting in $1000s of damage. Develop and prove the sys. before putting it on the primary turbo. Also on the primary it would increase lag. And the rule of 1/3. You can recover 1/3 of the waste energy per stage. Eg 160hp into the turbo 120hp bown the pipe and 40hp at the shaft
Gumby stay flexible.