Neil,

Here is the dwg you need.

Paul Lamar


Paul,
       Many thanks.  What I did not understand is that the bloke doing my
motor has already P ported it and the next bloke that is assembling the
motor asked me  what port timing I wanted.  On further discussion apparently
they grind the P port opening to give peak performance where ever you want
it. It is like putting in a different cam shaft just by how the port opening
is shaped. So in my ignorance which is getting larger as I deal with these
blokes, I just simply gave him the rev range  with max power (takeoff) at
7500 RPM and cruise 66% power at 5500 rpm and told him to work out the rest.
Will be interesting to see what they come up with.  He obviously knows a lot
more than me, which is not hard.   Neil.

That is unfortunate as I am looking at dozens of rotary engines
here at the Sports Car Club of America annual runoffs and very few
rotary owners understand how to build a manifold or porting to place
the torque peak and HP at the RPM we need. Most use side ports and
off the shelf Weber two barrel or Mazda four barrel carbs. 99.9% are
unaware that Mazda published an SAE paper on the Lemans winning P-port
4 rotor where all the critical tuning information was revealed.
http://www.rotaryeng.net/Mazda_R26B_US.pdf

The torque peak and max HP RPM primarily depend on the length of
the intake manifold runners and not on the shape or timing
of the P-port. The timing is exactly the same as a side port engine.

The problem comes when it is time to fit the manifold under
the cowl with the proper length manifold runners.

If the P Port is bored in at an angle it becomes far more
difficult and expensive to build the manifold.

We are not looking for the last one or two HP. We are looking
for about 250 HP at 7500 RPM with a design that is cheap
and simple to build.

I think we have achieved that goal with the straight in
welded SS tube design with a sheet metal slide throttle
and Teflon lining.

http://www.rotaryeng.net/intake.html
http://www.rotaryeng.net/fund-of-intake.html
http://www.rotaryeng.net/Welded-steel-p-port.html
http://www.rotaryeng.net/Lemans-rotor-dimensions-overlay.jpg
http://www.rotaryeng.net/in-mill-boring-head.jpg

Plus various YouTube videos on the subject under the key
word "PaulLamar2".

Paul Lamar