Paul and friends,
There are some newbies here that haven't followed and don't have
archival copies of the threads here to learn about the P-porting.  I am
one.

How about some pictures and explanations.  Awhile back I saw the slider
type valve, please explain.  Did I read that the p-port is used only for
WOT ?  And somewhere I saw a picture of the machining process... more
explanation and pictures please.

Are there any flying Rotaries in Iowa ?

Kevin
Naples/Ottumwa

A P-port is a large hole drilled directly into the rotor housing.
It breaths much better than side ports therefore the
engine develops more power over the RPM range used in aircraft engines.
About the largest hole one can drill in a 13B is about 2 inches in diameter.
If a butterfly valve is used to throttle the engine the aerodynamic
drag of the butterfly valve mechanisium limits the breathing.
A slide valve throttle on the other hand is completly out of the way when
wide open.

Paul Lamar

Let's take even a further step back:  A P-Port is a Peripheral Port --
meaning that the air intake is directly through the rotor housing, vs
the standard porting which is through the side / end housings.  A common
task for early 12a and 13b users was to partially fill the side ports to
create a 'ramp' so that intake air would more efficiently fill the rotor
housing  (vs the 90 degree turbulence of the un-modified side port.)
The peripheral port completely eliminates the 90 degree turn (as well as
permitting a significantly larger opening).  In a P-Ported engine, the
side ports are redundant, and thus are completely closed off.  Less
turbulence = better breathing = more power in a normally aspirated
engine.  The elimination of the butterfly valve in favor of a slide
throttle is another attempt to remove turbulence-inducing design
elements.  The name of the game here is high power in a highly reliable
(aka, simple) configuration.

Turbo / Supercharging can achieve the same power levels -- at the cost
of complexity, weight, and additional failure modes.  History on this
group has amply demonstrated that stock turbochargers fail under even
moderate amounts of boost when used continuously in an aviation
application.  Over the last 2 years, we've seen several failures of
stock turbochargers in flight which caused high anxiety / pucker-factor,
but fortunately no fatalities.  Better still, the builders involved we
able to share the post-mortem of the turbo chargers themselves which led
to interesting observations of the root cause(s) - as well as an
unexpected failure mode which greatly impacted engine rpm after a
failure.  This has led to better design specs for 3rd party units which
are more likely to survive aviation use (for those desiring to go the
boosted route).

Paul, I hope that sweet looking engine in the photos is Mark & my
engine!  The 'missing' components you emailed about earlier were ones we
wanted replaced by the hardened Mazdatrix versions -- Mark didn't send
them intentionally to prevent the engine from being built with the stock
components.  Good thing too, since it took a phone call to them after
your email to get everyone back on the same page.

Mark & Mark

Yes it is Mark. Tomorrow we will have the manifold welded
up on the engine to be sure it fits and should have it on the dyno.
I have a bit more wiring to do
and misc hooking up this and that. If everything goes OK we should
have some dyno numbers by the end of the week. John at Mazdatrix is
responsible for building engines with nearly 30 years experience
as he worked for Racing Beat in the early days. Perry Mick has been
flying one of John's engines for the last three years or so.

Dave says he thinks your muffler may fit on the dyno so we can
check it with your muffler.

Paul Lamar