> > > That is a comparison between bridge ported (Monster bridge port) and
     > > > periphery ported engines. There is no leaking problem. Both stock seal
     > rings are
     > > > untouched. The port area just like the factory periphery port, the port
     > area will
     > > > be filled and no coolant will be available to leak. The port is cooled
     > buy
     > > > inducted mixture while running. As in carburetor ice. After shut down
     > there will
     > > > be heating of the ported area from heat soak.
     > > >
     > > > The kids are driving giant periphery ported engines on the streets of
     > this
     > > > country every night to engage in tire smoking contests. There is no
     > increased
     > > > wear from high RPM operation because there is no high rpm operation in
     > aircraft
     > > > use. Even 7,500 RPM for takeoff is not high RPM. The 300 plus HP from a
     > 12A
     > > > periphery port or 330 HP from a 13B is at over 10,000 RPM. That is high
     > RPM
     > > > operation.
     > > >
     > > > The bridge ported engine has much more intake duration and overlap than
     > a
     > > > periphery port, and the kids drive Bridgeport engines to work every day.
     > It is
     > > > hard as hell for me to drive the race car around slowly, with either
     > port style.
     > > > With a 1.96:1 first gear. It goes 70 MPH in first gear. Jump in the car
     > stick
     > > > in 3rd gear and drive to work and back. With a 3.26:1 stock first gear
     > it is
     > > > no problem. It just has very little power at low RPM. You only use 40 HP
     > to
     > > > get to work anyway so how would you know if it didn't have enough power
     > down
     > > > low? My bridge port has 205 HP at 7,400 RPM. We don't use the engine at
     > that low
     > > > an RPM.
     > > >
     > > > If you could only get 200 plus HP out of a junk yard 13B with some pipe
     > and
     > > > epoxy, would that not be worth the effort?
     > > >
     > > > It took me one day to make a set of Pport housings and assemble the
     > engine.
     > > > It is a good idea. It has been done. It works just fine. There is very
     > little
     > > > new ground to cover here. Don't raise the top of the exhaust port at
     > all. Keep
     > > > the intake open duration short and use a wide port to get the flow. It
     > will
     > > > work so well you will not believe it. Even if you miss the tune up, get
     > the
     > > > timing wrong, get the porting wrong, and get the runner length wrong, it
     > will have
     > > > so much power it will scare the crap out of you.
     > > >
     > > > I refer you to Tracy's first take off with the engine turning some real
     > RPM
     > > > where it started to make some of it's potential power with the 2.85:1
     > box. That
     > > > is with a street port not a periphery port.
     > > >
     > > > Not enough rudder? Almost ran off the runway? I like talk like that.
     > > > So no full throttle until rudder is effective. Put that on a nice
     > placard
     > > > next to the throttle. Sounds like a P51-C.
     > > >
     > > > Lynn E. Hanover
     >
     > Lynn,
     >  The water leakage through thermal cycling I referred to was around the
     > epoxied PP tube, it may be misinformation, if so  - it's good to clear that
     > up. It may have come from early trials of home-made PP, that weren't done
     > properly, who knows, anyhow I accept your experienced  recommendation.
     >
     > I'm not looking for massive power, I'm looking for a mild street port in a
     > 12A demonstrator to test my aluminium end housings.
     >
     > So you suggest not raising the port IC from stock timing, to keep the
     > duration short and the port wide. I'm a bit conservative and am concerned
     > that too wide a port (especially in the 12A) will cause problems with the
     > apex seal - so I will not go beyond the width of  the exhaust port for that
     > reason.
     >
     > Given my particular situation what IO and IC would you recommend  Lynn
     > George (down under)

     George, in a msg to this list about 3 years ago Paul Yaw suggested a 1.5" dia PPort for a conservative beginning and thought that this would yield
     ~200 HP in a 13b.  His assumption was that we would build multiple engines until we found the best combination for aircraft (afterall, HE can build
     one in a couple of hours probably).
     Ken Powell

That is a good idea. We should have a build a rotary contest at Sun & Fun workshop.
I think Dennis Hayes can do it in five minutes.

Paul Lamar

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