Paul, I read your article in Kitplanes, but I am confused about the exhaust
valve being the cause of  huge losses.

Is it because of the restriction of the valve? Or is it the metallurgy not
allowing higher operating temperatures?

Your article was a great read by the way, I saw your web site, please
subscribe me!

You were looking @ roots blowers, I would suggest that you look @ Lysholm,
or screw type compressor.

The Roots blower is about 50% efficient, the Lysholm is closer to 85%, lots
less heating.

Mazda used them on their Miller cycle engine in the Millenia.
How is your recovery turbine coming?
Thanks,
Tom Bowman

It is a bit of both. The kinetic energy is what drives the turbine.
In other words the flow of the exhaust gases. If you put any kind
of obstruction in the flow path it will slow the flow. The
secondary effect is the heat lost to the exhaust valve. Anytime you withdraw
heat from a gas flow in a pipe the volume of the gas and hence the flow
rate will be reduced. Check out my youtube videos on the subject.

http://www.youtube.com/watch?v=KcqP3U1tAPc
http://www.youtube.com/watch?v=bkWbsO0C8x8
http://www.youtube.com/watch?v=6Po5jsrYMK4

I also have a video of a talk I gave at the World Motorsport
symposium in Oxford the UK on the ACRE website.

http://www.rotaryeng.net/Oxford-640-4802.wmv

It is kind of on back burner until I get my dyno working.

Paul Lamar