Re Liquid cooling:It's interesting to note that various models of
 motorcycles continue to transition from air/oil cooled to coolant/oil
 cooled.And, those same models continue to get lighter.That says to
 me that liquid cooling, while somewhat more complex in some ways
 (though less so in others), isn't heavier.Maybe someone knows of a
 counter example..

 Regards,

 Matt-

 Matt,
 much of going to liquid cooling isn't about the weight. It's about
 combustion control. Liquid cooling controls the temperature of
 the cylinder
 head much better than an air cooled head. This allows making
 more hp for the
 same displacement. When an air cooled cylinder head gets hot,
 the combustion
 chamber becomes very prone to detonation, with this being the hp
 limitingfactor on many air cooled applications.
 Larry

 Right.. For a given displacement, more horsepower can be had
 from a
 liquid cooled engine.. Countering the added weight of the liquid
 cooling system.

 Also, people might point out that liquid cooling is for emissions.
 While I agree with that, I would say that an engine that produces
 fewer emissions often will run cleaner and fewer service difficulties.

 Matt-

 Matt,
 With modern heat exchangers it is veryhard for an air cooled
 engine to get anywhere close to a water-cooled engine in
 hp/cu.in.When you consider all factors I believe the flexibility
 of configuration isimpossible for an air-cooled engine
 to match.The switch to water cooling in modern motorcycles WAS
 NOT caused by emissions requirements. The change was well
 underway before those requirements became very stringent.
 Packaging was the reason.With water cooling you can make an
 inline four cylinder short enough to be anacceptable power plant
 for transverse mounting in a motorcycle.VariousV
 configurations are also possible that wouldn't be able to be
 cooledif air cooling was chosen. Getting back on the proper
 rotary track, air cooling of the rotary while possible, just
 isn't the way to go. The liquid cooled version will always
 be a more flexible package.
 Bill Jepson


 While I would agree that when simply comparing liquid and air cooled
 engines, liquid cooling is more efficient in every way. However, to
 compare a motorcycle, or automotive engine for that matter, with an
 aviation power plant is not a good way to go about the discussion.
 While power-to-weight and packaging are the main concerns in in
 automotive and powersport application, aviation engines seem to
 value reliability above all else. In short, while a liquid cooled
 engine may prove better thermal protection and a greater power output
 enough to justify the additional weight, reliability does suffer no
 matter how simple the liquid cooling system. While the air cooled
 engine may suffer from lack of power, it will NEVER (emphasis added)
 suffer a malfunctioning water pump, thermostat, leaking coolant hose
 or radiator. While I personally prefer air cooling for aviation use,
 more opinions on the matter may be needed before I
 dedicate myself
 to either system.
 Vladimir

 You don't have much of a choice with the Wankel as it is too hard
 to cool the center housing with air. If you add a blower that
 will suck more fuel. An air cooled one rotor might work as long
 as it is not charged cooled.

 Paul Lamar


Hi Vladimir,

Here is a link that Paul published about 3 years ago.  He did try to
find more info on this rotary engine.  You might get lots more info from
them.  If you could find them.

http://www.youtube.com/watch?v=Epb7-fyXtOo

Also Vladimir here is a link for a 30,000ft rotary A/C engine.  Do you
have a Hyperbaric chamber or a mountain close by?

http://www.bmaa.org/upload/flo/fo1007.pdf  scroll down a bit

http://www.parajet.com/fileadmin/user_upload/expeditions/everest2007/EverestEngineDevelopmentReport.pdf


Marc Joseph