> Jerry Hey wrote:

 >
 > I think that my wife, Joy,  has determined the peripheral port size
 > and timing  of the Leman Engine.  Here is what we did.   First I
 > measured the inside vertical height of a l3B rotor housing.  This I
 > determined to be 9.44 inches which we divided in two (4.72")since we
 > were only interested in the top half where  the intake port is. Now I
 > step out of the picture and Joy takes over.   The second step was to
 > import the drawing of the Leman engine into PhotoShop where it was
 > cropped to eliminate all but the top half of the rotor housing.  This
 > was saved as an EPS and exported to PageMaker.  Then, in PageMaker
 > she drew a line 4.72" long and scaled the eps image so that the
 > inside top of the rotor housing and the horizontal center line
 > matched up with the ends of the 4.72  line.   At this point the Leman
 > drawing was at one to one.  Then, using Pagemaker  tools,  Joy
 > measured  from the center line to the bottom and top of the P Port.
 > It was 1.2" to the bottom and 3.188 inches to the top.  That is close
 > enough to use a 2"i.d. x 2.25 o.d. aluminum tube for the insert.  The
 > runners appear to be same diameter as the port.
 >
 > Don't know what I'd do without her.    Jerry

 Jerry, I'm be very interested in your progress.  Please let me
know how your doing the PPorting.
 IE,   Mill or die grinder.   Will you have the port set at an
angle like Power Sport does?  Are

 > you going to thread the insert?  Any help here is appreciated.  Tom Webber.

Tom,  The P-Ports will be NC milled.  I don't think it is necessary
to thread the insert although this is what Jim Mederer says.  I know
that others have not threaded and have not had problems.   The angle
of the insert is another question.   I would prefer it to be
perpendicular to the housing. However,  this places the runner at a
weird angle if you intend to go over the top of engine.  Better to
just have a couple of 90 degree bends that can be readily bought.   I
am not locked into anything yet.   The P-Port timing is still a
mystery to me.  I tried to compare Paul Yaw's numbers with the tech
drawing of the Leman ports and they did not coincide.  Maybe I did it
wrong.    I would be  happy to just copy the Power Sport ports, if
only I could.  Jerry
--
Jerry Hey

Tailwind & Rotary Engine Support

http://www.j-winddesigns.com

mailto:j-winddesigns@thegrid.net

Jerry, If you just want to know the timing on the intake and the exhaust ports here's
a simple way to find out.
Get a piece of plexiglass, lexan, etc.  Locate it on the  rear housing using the dowel
pins. Cut a hole in the center of the plexi large enough for the e-shaft ecentric to
pass through. Mark the port locations on the plexi when it is aligned with the dowel
pins.
Install the e-shaft in the rear housing that you used to make the plexi templete, with
the e-shaft pointing up. Add one rotor and rotor housing. Lay the plexi on the rotor
housing so that you can see the rotor and apex/corner/side seals as it turns under the
plexi. Be sure to use dowel pins in the rotor housing so the plexi is lined up
correctly.
Install a degree wheel on the e-shaft and make a pointer and attatch it to the rotor
housing so it points to 0 degrees when the rotor is at TDC on the compression stroke.
As you turn the e-shaft in the correct direction you can see the ports open and close
as the rotor seals pass them.  Just read the degree wheel as the ports open and close.

Use a grease pencil, or felt marker to locate the ports as accurately as you can.
You can consider the location of the p-port and fine tune it's location this way
without ever cutting the housing.

We haven't cut a p-port. but the object of all this port timing is to have as little
overlap between the intake and exhaust ports as you can manage. One of the reasons the
p-port engines idles so roughly is the same reason a wildly camed piston engines idles
so roughly.  The exhaust port is still open when the intake opens and the intake port
pulls in exhaust gases and dilutes the intake charge. On the piston engine the exhaust
valve is still open (large overlap between the opening of the intake and closing of
the exhaust ) when the piston starts down on the intake stroke, and thereby pulling in
some of the spent exhaust gases to dilute the intake charge.  On the piston engine
both valves are in the combustion chamber so they are connected.  On the rotary the
pocket on the rotor (the combustion chamber) also connects the intake port to the
exhust port.

On the Renesis engine Mazda went to side exhaust ports to virtually eliminate this
overlap.
We aren't as concerned about Gas dilution at idle on aircraft engines as they are for
an automobile, but the overlap still affects power at high RPM just as it does at low
RPM. At high RPM it is just not noticed as much.
Just as important to making power for us with port timing, is also exhaust
scavenging.  If the exhaust system isn't "tuned" for max scavenging of the spent
exhaust gases, there will be some left in the combustion chamber to dilute the fresh
charge even with no overlap of the ports.

In doing the p-port you are limited to the amount of intake port timing you can choose
because of where you have to put the port. Someone mentioned earlier about making the
port as wide as possible so you can have a little more flexibility in the timing.
Study how Maxda did the exhaust port shape for that reason. That port enters the
housing above where it comes out on the inside and is oval shaped on the inside but
round on the outside. That oval shape allows the port to open as early as possible to
start emptying the exhaust gases, but to also close as early as possible to eliminate
as much dilution as possible.
It appears to me that, this change in port shape will cause some exhaust gas
recirculation because the shape change affects the pressure wave, and looks as if it
would cause a slight reversal just outside the inside shape (within the housing
itself). You would think that Maxda researched this, and if so then they either
concluded it wasn't a big deal, or something.
Intake tuning, that is the length of the induction system/tubing, has alreadfy been
discusse here a lot.

A lot of little things add up in the HP game.
Royce

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