This is a case of fitting the data to the theory.
These charts from Taylor were done close to 50 years ago but they
agree with the charts published in 1995 by Heinz Heisler in his book

Advanced

Engine Technology. Those are also attached.

Lets examine these charts a bit closer. Look at the lower right Taylor

chart.

As far as I can tell the length of the pipes in this chart are 50 inches

long!

That is if I am interpreting L/S correctly as the length of the piper over

the

stroke.

The bore (B) in this engine is 3.5 inches. There are three different pipe
sizes tested namely .461xB, .326xB  and .226xB. That translates to 1.6
inches in pipe dia., 1.14 inches in pipe dia. and .79 inches in  pipe dia.

Since the bore area of a piston engine is analogous to the area of the
face of the rotor lets work out the corresponding rotary pipe sizes.
The face of the rotor is about 3 inches wide and about 7 inches long
as I recall. That is an area of 21 square inches. Lets come up
with an equivalent round circle diameter. Divide by pi and take the
square root. The square root of 6.68 will give us the radius. That equals
2.58 inches radius or a bore of 5.16 square inches. Basically the rotary

is

a large bore short stroke engine.

Agreed- except with 5.16 sq", which should be 5.16 "Diameter

The area is 21 sq" as you say!

I get a (S) stroke of 1.9" ( 40 cu"divided by 21sq" = 1.9)

With a (L) length as 16.68" ( where L/S=8.78) sounds reasonable.
With 8.55x 1.9= 16.25" ; 11.20x1.9=21.28" ; 11.44x 1.9= 21.73"

Where D/B= .461; ( B= 5.16) D=  2.37"
Where  D/B = .326; ( B =5.16), D = 1.65"
Where D/B= .226 D =1.16"

Seems about the same, except for the length where you got confused about the
area.

Am I wrong to assume there is only 10% difference between your figures and
Jerry's ?

George (down under)

Absolutely wrong. Notice the length of the pipe on the piston engine was 50 inches
long for 2500 RPM and the optimum length on the Le Mans engine for 6000 RPM
was 16 inches long.

We are nowhere near a workable theory for rotary engines. I am just pointing out
some similarities with piston engines. Don't try to read something into this that 
is not there.  All of this is empirical. Determined by extensive
experiment on one piston engine of a given bore and stroke. The work done by Taylor 
is sure to scale only to piston engines. You keep sounding like you are going to come
with a magical number for the pipe diameter and length. We have a long way to go 
to come up with a workable theory for rotary engines. Forget it. The only way you are
going to do that is by extensive experimentation on a dyno. Build the dyno.

Why bother anyway? The solution is staring you in the face. Mazda has done it for 
you. Nobody anywhere has a built a rotary engine with something other
than 2 inch p-port pipes that comes close to the 240 HP at 6000 RPM achieved by the
the Le Mans engine. Copy the Le Mans engine exactly. What is it about this that is 
so hard to understand.


BTW Why mess with a ancient 12A engine? It is no lighter than a 13B. 

Paul Lamar
 
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