The rotary engine suffers from high BSFC at low loads.
  Low loads are the name of the game for automotive engines.
  GM found back in 1978 that the temperature of the rotor face had a strong
  effect on the low load BSFC. A 9.8% improvement in the BSFC
  was possible with a hot rotor at low loads. Higher rotor temperatures gave
  lower fuel burn at low loads. However if the rotor was not
  cooled at high loads the cast iron over heated.
  GM got a patent in 1976 on a hot rotor face insulated from
  the rest of the rotor. Here is a pdf on the 3,995,602 patent.
  The SAE GM paper on the subject was 780419.

  The obvious solution is to control the temperature of
  the rotor as a function of the load on the engine.

  The amount of oil cooling on the rotor is now controlled
  by a ball and a spring that opens at a certain RPM.
  RPM is not the problem. Engine load is the problem.
  A way can be found to cut off the oil cooling to the
  rotor at low loads regardless of the RPM. In other
  words run the rotor face as hot as possible at all RPM's.

  One mechanical way of doing that is insert a stationary tube
  in the center of the e-shaft that moves back and
  fourth controlled by a servo that senses engine
  load and cuts off the cooling oil supply to the
  rotor. A peice of cake for todays computer controlled
  engines. In fact it need not be controlled by a computer
  or electrical servo but by a simple air servo connected to the
  intake manifold pressure.


  Patent applied for :)

  Paul Lamar



  Sounds like it should work ... however ...

  Common sense (which often fails me) tells me that something else is
  really going on in during the compression/ignition cycle that is not
  addressed by the GM research. I find it hard to believe that somehow
  the gas charge "knows" about a 100 degree temperature difference in a
  metal surface that is whizzing for the briefest instant during the the
  ignition/combustion process. It all happens in about 0.01 seconds. By
  far the majority of the the gas-charge is separated from the rotor
  surface by only only a fraction of an inch, but this fraction of an inch
  amounts to millions of molecules of separation. That seems like miles to
  me in my microscopic world-view. And the theory is that what would
  appear to be a barely significant temperature difference in the middle
  of a thermodynamic inferno is going to somehow extract 10% more energy
  out of the reaction ?????? I dunno???

  In defense of the theory, the operation of glow-plugs come to mind, and
  of course, pre-ignition due to a build up of combustion-chamber deposits
  can really affect the fuel burn. But these examples relate to very high
  temperature surfaces. Back about 1970 I had a little Ford Bronco that
  would start running really rough. A few times I was forced to pull off
  onto the shoulder of the road and remedy the situation by dribbling
  coffee from my thermos bottle down the throat of the carburetor as I
  raced the engine to help the beast "clear its sinuses".

  So yes, combustion is/can be influenced by surfaces, but at 300
  degrees?

  I have often wanted to experiment with extremely high-voltage, perhaps
  radio-frequency spark plugs. (RF currents are not dangerous to humans,
  since the molecules in our bodies are to sluggish to respond to the
  signal as they do in direct currents.) So by applying a huge RF voltage
  between the upper and lower plugs one might be able to get very
  efficient ignition to occur. The design problem I have not yet solved
  is what the nature of the combustion chamber and rotor surfaces would
  need to be to force the RF electrical discharge to either arc across the
  surface or create a blast of plasma through the gas-charge rather than
  jump back into the housing metal for part of its journey to the other
  spark plug. Ceramic engines? Maybe.

  Patent soon applied for :)

  R Berglund

  There a lot of other things discussed in the SAE GM paper but those, in the
  opinion of the GM engineers, could be addressed with high pressure direct
  injection. It had mostly to do with the raw fuel wetting the walls of
  the combustion  chambers including the compression chamber and the exhaust chamber.
  Mazda addressed some of those issues with the RX8 and how it recycles
  raw fuel with the side exhaust ports.

  IMHO it is just a matter of time before this problem will be solved.

  Paul Lamar

    Cell phones are 900Mh, Virg

Here is how to have your modified 2.5 rotor RX8 get 50 MPG at a steady 65
MPH using an AIXRO one rotor kart engine mounted on
the back of the stock RX8 differential.

First read this. http://www.rotaryeng.net/RX8-TC-eng3.html

Here is a cheaper and quicker way of testing this concept. Get an AIXRO Kart
engine and mount it on the back of the RX8 differential. Remove the stock
rear cover. Use a second pinion gear and run the AIXRO only at cruising
speed with a one way clutch to disconnect it at lower speeds.

Assume 30 inch tire. That is 94.248" circumference so that is 7.85 feet in
circumference. At 95 feet per second or 65 MPH that is 12 revs per second or
720 RPM times 4.77 is 3434 engine RPM.

So you need a 2.17:1 planetary reduction given 7452 RPM for the AXIRO engine. That is
also 114 revs per mile per hour or 96 MPH at 11,000 AIXRO max RPM.

BTW for those on here that have not yet heard a Mazda 13B 1991 Turbo II engine
more or less stock went 229 MPH at the recent Reno air races in a RV6 experimental
airplane.

Paul Lamar

Hi Paul,

 I happen to have a very good friend across the Pond (remember, I am in
Europe) who is running a prototype rotary engine on extremely lean burn with
Dynamic Spark Ignition. Somkinda radiofreq you know. BSFC is extremely low
but confidential information so if I tell you I'd  have to kill you. I won't
do that. Very low BSFC indeed. But today is Christmas: put your spark plugs
to rest and light up your candles. (Funny: in french they are both called
"bougies").

I wish you a merry Christmas Paul . And I wish merry Christmas to all the
readers (and contributors in particular) of Rotaryeng.net

Randolph in Paris

Microwaves can boil water. Why not fuel?
Brilliant idea.

Paul Lamar