Regarding the 4 cylinder 4 stroke engine, I must have had a brain drain
when I wrote that there was one spark event per revolution. Clearly
there are two.

Regarding the two rotor Mazda rotary, I stated that there were 3 spark
events per revolution of the shaft. At least two people responded, both
saying there was only one spark event per shaft rotation.

My statement was based on Bruce Turpentine's statement concerning
compression testing in his overhauling a 13B DVD. Bruce states, in the
(crude or gross) compression check segment, that when you rotate the
e shaft by hand you should get 6 compression "chuffs" in two revolutions
which equates to 3 in one revolution. In the shop we have confirmed
this. My reasoning on the number of spark events was that every
compression stroke ought to have a spark event, thus my statement that
there were 3 spark events per revolution of the eshaft. I am confused.
Where did I go wrong?

Doc Custer
Retired Software Engineer and sometime Audiologist

Bruce is wrong :) One spark per rotor per 360 degree revolution of the e-shaft.
One chuff per rotor... per 360 degree revolution of the e-shaft. The rotor turns
at one third the e-shaft. It has three sides. You are only getting a chuff from
one side of the rotor per e-shaft 360 degree rotation. Each side goes through the
four strokes. Therefore a compression stroke comes up once per e-shaft rotation.
It take 3 revolutions of the e-shaft to check all three sides of the rotor.
Of course the other rotor is 180 degrees out of phase.

The way the Wankel engine works is Excedrin headache number 360 :)

Paul Lamar ...No rotor no motor.

Doc,
   The confusion stems out of trying to compare with piston engines,
which cycle through all cylinders in two revolutions of the crank. The
13b takes three revs. to cycle through all three faces of the rotor.
    It is also the source of the confusion for displacement.  2600cc
in two revolutions, When you count the displacement in a piston engine
you can just multiple each cyl x number of cyl. In a 13b that is
3900cc (6 faces x 650cc), but it only uses 2600 in two revolutions.
   It is further complicated by the three faces using the same spark
plug, which doubles the spark events per plug. We can't count piston
engine waste spark because it doesn't take as much energy as a
compression stroke spark.
    The EDIS coil has four leads and two coils. It fires 2 leads at a
time. One is waste and the other is compression. On the 13b they would
both be compression which increases the duty cycle on the coil,
Becuase the full strength spark needed on compression stroke.