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

Paul,

Great video of the turbo-compound diesel.  I'm a little biased
but I bumped the ratings up a little:)
It is hard to tell how the gas flow moves on the blow down turbine.
I am guessing it comes in centrally goes through a diffuser,
then the turbine and exits in the scroll?  Opposite of a
typical turbo-charger turbine.  Do you have an idea?  If
so I think I may have found a useable turbine at Jet Beetle in Taiwan.

Doug in Japan

Here are some pictures you may not have seen.

BTW they have gone the CW R3350 route on that engine upping the boost and it is
called the DD16. It now has 600 HP up from 450 with I suspect the same
displacement. No figures on the fuel burn so far. Apparently the sky is
the limit much like it was on the R3350. That must make one heck of an
18 wheeler :)

Paul Lamar