Hello Paul,
I read with great interest your article on the turbo compound engines. Some
of the message board writers  get confused between compound turbos and turbo
compound. I think this is a great technology that needs further research and
application. It is definitely useful on constant speed highly loaded engines
as aircraft and stationary engines are. I am also familiar with the use of a
large turbine in the ducted exhaust of a gas turbine engine. They are used
for natural gas pumping stations to drive the compressors. Similar use in a
larger scale to the Curtis Wright R3350 TC.

I am wondering if this would be practical to apply to an automobile engine.
How do you size the turbine as compared to a conventional turbo charged
engine, especially if you do not supercharge the engine? The premium price
for 92 octane fuel is not usually offset with much better fuel ecomony. How
do you couple the reduction drive to the turbo compressor shaft end?

I would think you are using a 20B with the sequential (compound) turbos
removed and the engine "street ported", for that power level. For your turbo
compound, are you working on the turbocharger sized for a turbo normalized
type application? For best performance, I can see where two systems might be
required.
Thank you for the great article and your time.
Sincerely,


Dale Davies

For aircraft use the lowest cost way is to use a turbo charger with
the turbine sized to provide power to the e-centric shaft
as well as to the compressor. That is minimum heat loss situation. For cars
one might want to use a computer controlled clutch to disconnect
from the e-shaft so the compressor will accelerate rapidly and
build boost faster.

The power can be taken out of the compressor (cool) end of the turbo charger
with a flexible coupling to a small diameter shaft as the torque is on the
order of only one or two foot pounds. The HP comes from the high RPM.

I would P-port the 20B as that is a more efficient way of getting
air into the engine.

The automotive application subject came up in a presentation I gave
in Nov 2008 at the 2008 World MotorSports Symposium in Oxford UK.
The key is to use a variable nozzle turbo charger and down size
the engine so it is working harder while at constant speed on
the freeway.

You can download a video of that presentation. The video
is 300 megs so it will take about two hours to download it.
I suggest starting it before you go to bed :)

http://www.rotaryeng.net/Oxford-640-4802.wmv
Also read
http://www.rotaryeng.net/RX8-p-port.html
and
http://www.rotaryeng.net/RX8-TC-eng3.html

Ed VanDyne has started a company called Super Turbo to provide
turbo compound solutions.

Ed VanDyne 2 <Ed@VanDyneSuperTurbo.com>

Paul Lamar