Paul

Its a rainy Sunday afternoon and I'm organizing my rX-files again. I
took the time to print  Shimizu San's patent out and read through it
more carefully.

http://www.rotaryeng.net/pat20090101103.pdf


His patent reads more like a technical paper which is wonderful. In
summary he states that in Mazda  engines the flame front from the
leading and trailing plugs meet after the flames hit the sides walls.
Having them hit the side walls first redirects the flame front
(combustion pressures) towards the rotational direction.  Hence the 16X
5mm reduction in width.
Probably another reason is rotor mass as bearing loads become
unacceptable over 8500 rpms.

IMHO opinion for our 13B engine the same came be done with dual leading
highly efficient ten mm dia. spark plugs.  A  multiple strikes
capacitive ignition would only be beneficial if the sparks can are
faster than the flame front. As the engine   increases in rpm the
benefits of multi-strikes ignition system become more favorable IF the
flame front is slower than the spark duration event.

Question.  Does the rotary engine suffer in efficiency vis-a-vis the
piston engine because of more unburnt hydrocarbons exiting the engine,
or is it because the combustion chamber characteristics  (shape,
pressure, duration) are less than ideal for creating mechanical energy.
Of course burn rates in different types of fuels or combinations also
change the characteristics of combustion gas propagation.

Doug in Japan

I still have not seen any data on the 3D flame front and mixture
distribution within the combustion chamber in real time for a range
of RPM's and mixtures. It is way too hard to do that so I don't think
anybody really knows what is going on in there or when it is
happening. Somebody needs to build a glass rotary engine :)

IMHO making the rotor narrower is not the way to go.
As you pointed out it limits the RPM and makes
a p-port version less efficient VE wise. Rotor mass to rotor
bearing area ratio is the key parameter. A narrower rotor leads
to a less favorable rotor bearing area and worse..rotor bearing
width to diameter ratio. Why shoot yourself in the foot :)

The piston engine has been exhaustively tested with a wide range of
bore to stroke ratios over a period of 110 years and engineers are still
learning about what goes on in there. Probably a million more man years and money
have been spent on piston engine R&D than on rotaries. Here is a small
sample of what Porsche is doing with direct injection. So far Porsche is
the world wide leader in gasoline direct injection IMHO.

The only thing one can do is cut and try different ideas. That is going
to take a lot more money than Mazda has and another 50 years.
Unless of course some of the remaining major players in the car biz
start building rotary engines.

Paul Lamar