Paul,

I've been thinking about the turbo compound idea a bit since we  talked about
it last Sunday.  I'm thinking that the exhaust turbines used for a
turbocharger aren't really that well suited for putting horsepower  into the
crankshaft.  They are designed to spool up quickly and optimized  for driving
a centrifugal compressor.

I was looking at the turbocharger used on the P-38 and the B-17 and  it's
fairly large in diameter with the exhaust exit well away from the  shaft so
the force on the blades work a longer moment arm.  I think it also  turns
much slower.  I'm thinking a configuration like this would be much  more
efficient for our purposes and would allow normal gears to feed the  power to
the crank.

Steve Brazil

Perhaps something like this? Cheaper and more durable than building  a two liter
four cylinder turbo charged 500 HP piston engine. It should burn at  least 5% less
fuel per HP generated than the very best piston engines, given  there is at least
as much wasted energy in the exhaust as comes out of the engine shaft.

Paul Lamar

Yes!  I've always thought this was the best idea proposed.  It's
concentric with the motor and could use a planetary, if needed, to
transfer power to the e-shaft.  The new larger rotary would allow a
larger diameter turbine still and slow the revs.

Chris Cosman

Due to the large diameter of the turbine and the high RPM of the rotary
I don't think the turbine needs gearing.