Mr. Lamar,


I have read with interest the articles about turbo compounding. I am not
an engineer but I have served in the US Navy as a Machinists Mate and
worked for many years as an automotive mechanic. Somewhat of a gear
head, I guess. While I spent only 3 years in the USN, their “A” school
for the rate, and my service at sea made quite an impression. It has
always made me wonder about the amount of energy wasted by current
automotive technology. When I was active, most propulsion was by high
pressure steam but its efficiency was quite remarkable.


A basic steam cycle started with pure, de-oxygenated water that was
pumped at around 1600 PSI into a boiler. What came out the other end was
1200 PSI dry steam at around 900°F. It was then routed through a nozzle
block to a high pressure, steam turbine where a great deal of the heat
energy was converted to rotary, mechanical energy. The exhaust of that
turbine was then directed to a low pressure turbine where additional
heat energy was converted and the resultant exhaust (that at this point
was basically saturated steam under a partial vacuum and at about 70°F)
was collected in the main engine condenser where it was pumped through
another heat exchanger located in the boiler exhaust stack to allow the
condensate to be preheated before returning to the feed pumps where the
whole cycle started over. 1200 PSI of pressure and more importantly,
800°F+ of heat removed. From a 6 inch steam line we generated around
40,000 Hp at the screw if my memory serves. (Please remember this is a
REALLY simplified description)

In and internal combustion application, chemical energy is again used to
create heat energy that in turn is converted to mechanical energy for
use in our transportation systems. Along the way, MOST of the heat
generated (the actual energy, the “good stuff”) is wasted by radiating
heat from the engine surfaces, radiators, condensers, exhaust and now
catalytic converters. I have always wondered why there is not a great
deal of focus on the capture and use of this energy!?

In the compound engine, an attempt is being made to finally do this and
it seems like a step in the right direction. My question is this. Why
stop at a single turbine wheel? Outside of weight and space, which may
be more than compensated for by the extra mechanical energy generated,
what keeps us from exploring something like a multi-stage turbine being
developed to convert some of the currently wasted energy? I would prefer
this not be long winded. Are you aware of any experimentation in this
area?? It would seem that the exhaust temps on the Wankel rotaries would
be an ideal source of energy to boost efficiency.

Anyway, enough rambling, I really like your website. It is extremely
informative. I have a dream to built a rotary powered kit some day, but
I also have a wife that has a dream of a closet full of nice clothes…..

Merle Zingg

If I could get the first turbine to fly again I could die a happy man.
I don't understand why the entire world does not understand what you just
described.

Rumor has that Boeing is working on it for UAV use. Mazda should be working
on it all out as the rotary is uniquely suited to turbo compounding
as it has no exhaust valves which were the Achilles heal of the early
1950's turbo compound engines. It should be Mazda's highest priority
as it holds the potential of reducing the world wide automotive fuel consumption
by 5% or more. Lots more in the case of aircraft engines. The amount of money saved by
this technology world wide is many MANY orders of magnitude more than what
it would cost to develop.

Wives they can be hand brakes sometimes. There is no question about it.