A few days ago, going through my p port stuff, I ran across a drawing
I did comparing my  p ports with the Leman' ports.  Since I had a
housing to measure and access to a height gage, I added Paul's p
port.  The drawing requires studying for a minute to get oriented. It
shows the port's locations referenced from the horizontal center line
of the housing. You will appreciate this when you are preparing to
hit your housing with the hole saw. If you want to do the math you
(Paul and Rolf and a few others who are able) can come up intake
opening in terms of degrees.  it satisfies me to be able to make some
obvious comparisons:

1.  The Leman's port opens and closes a little earlier than Paul's.

2. The leman's port is slightly larger then Paul's. Both are much
larger than mine.

3.  All three ports close at nearly the same time with Paul's and
Mine being virtually identical.

4. My port opens quite a bit later than either the Leman's or Pauls.

  I think Paul's port will perform very much like the Leman's port,
which was the goal.   It has a little less overlap and a little less
area, both of which I think are beneficial at our rpms.  Paul, would
probably argue that bigger is better.

  My port will perform more like the Power Sport port which peaked at
215hp just over 6000 rpm (I forget the exact number)  It probably
will do significantly better at 7500 rpm but we won't know until it
is tested.  In theory, more rpm favors the larger ports but remember
that 7500 rpm is nothing in the world of P Ports.  Paul's port is
probably good to 11,000 rpm or more.   I think mine would run out of
power above 8,000/8500 rpm.

When you look at all three  ports lined up lined this, it is pretty
clear that timing is not that critical or even that optional. The
ports have to be located about where they are. The centers of the
three ports are within .250 in.  of each other.  So if you really
feel like "engineering" your p port, then go for it. Just stay with
in the limits of the drawing.  :)

  Soon we will have a few p ports running and then the fine tuning
and the fun can begin.     Jerry

Jerry,
We don't agree on everything that's for sure, but here's an area we do agree
on - we won't talk on port sizes.

If I could just add a couple of things in this discussion-
1. Paul's find on the German document which showed the initial P-Port
opening, did allow some air to escape to the exhaust and confirmed that this
was a good thing as it helped evacuate the exhaust( I assume at low RPM/
Idle), helped to stop exhaust entering the inlet and I guess help any
remaining fuel burn up in the exhaust.
This is all good provided you delay the fuel until the exhaust closes - as
in Tracy's ECU.

I still believe the PP can be .5" different ( one from another) and still be
fine.

I was wondering why you were being so pedantic, but it seems you were just
trying to clearly demonstrate the different ports.
George (down under)


The Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site. http://www.rotaryeng.net
Copyright 1998-2006 All world wide rights reserved.