Paul,  here is another drawing comparing very clearly my p port and
the
Leman P port.  Both close at nearly the  same time but the Leman
port
opens much earlier.   Once one determines the closing event timing,
the
opening event is fixed by the diameter of the opening.  I did not
want
an opening larger than our operating range required, thus the bore
of
1.5 inches which was determined by Rolf to be adequate up to 8500
rpm.
If one wanted to run the engine at even  higher rpm, the capacity of
the port  would have to be changed . However,  my goal was to have a
safe (easy on seals), efficient p port that would operate up to 7500
rpm. If my engine generates 240 hp I will be thrilled.  But if it
only
generates 220 hp,   that will be o.k. too.      Also,  George was
right,  it is much simpler to simply bore a round hole as opposed to
grinding a rectangular opening.  I was relieved when it was
determined
the round hole  would be sufficient.   jerry

Jerry,
While I've got your attention can I ask what is the shiny area around
your
port ( inside of the housing) is that a finish grind. If it is I
would be
worried about the Teflon coating being abraded off in that area.
Also your original design showed a distinct edge relief at the top
side of
the port and that no longer shows on your prototype.
My advice is that an adequate convex relief ( airfoil shape) would
enhance
flow characteristics - in the right direction.

I may be overly concerned about these things, but I thought I would
mention
them just the same. Perhaps you could comment on these issues?
George ( down under)

George,  We have not touched the housing surface at all.  There is no
finish grind that touches the housing.  Perhaps what  you are looking
at is the thick wall of the insert.  It is .375 inches thick.  This was
originally intended to provide material for grinding a more rectangular
shape.  Now that I no longer intend to do this,  I may cut the insert
wall thickness down to about .188 in the future.    As far as grinding
relief on the top edge,  I will leave that to after we have run the
engine.  If it does not perform as well as I think it will, then we can
try refining the ports.   Based on what I have seen,  ( which is quite
limited)   it is not necessary to relieve the top of the port.    I
enjoy reading  your pursuit of the mysteries of the p port.   Thanks,
  Jerry

 
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