Charlie you are forgetting that Power Sport has been flying p-ports for
years in RV's. Allan Tolle has flown many times coast to coast and
entered several Sun & Fun races. No landing problems as far as
I could tell. Tracy Crook never idled his RV-4 engine below 1800
to 2000 engine RPM 829 to 922 prop RPM for years because the Ross
gear box would rattle mightily. He also does not slip when landing.
The port timing has little to do with the p-port overlap
problem. This is mainly due to the pocket in the
face of the rotor. That is the main avenue for the exhaust
gases to enter the fresh mixture area. That path is open from
the moment the apex seal passes the lower floor of the p-port
intake until the next apex seal passes the ceiling
of the p-port exhaust. Then the process soon begins again
with the next cycle. In other words it is open the majority
of the time. P-port intake timing has little to do with it.
When the pressures are the same there is no flow.
This delicate balance of pressures is the main
reason intake and exhaust pipe tuning is so critical
with p-ports. It is quite remarkable that Racing Beat
can build a turbocharged 3 rotor p-port engine developing
over 300 HP per rotor on gasoline. One would think the
turbo charger would blow all the fresh mixture down
the passage in the face of the rotor and out the
exhaust port. This does happen to a certain extent
but the saving grace is the pressure in the exhaust
is only slightly lower than the pressure in the intake.
Never the less p-ports have the HP per rotor record for
normally aspirated wankel engines as far as I know.
Perhaps there is bridge port engine out there that generates
more. Bridge ports are half peripheral port and half
side port.
The p-port Lemans engine generated 120 HP per rotor
at 6000 RPM and 172 HP per rotor at 9000 RPM. Even the side
exhaust port RX8 engine generates only 280 HP at 9000 RPM
or 140 HP per rotor in its best stage of tune. The street
version will be lower HP. This in spite of the fact the
side ports are roughly 20% larger than the old 3rd gen
side intake and peripheral exhaust ports. I digress.
In a side port the passage is much more restricted. The ultimate
reduction in overlap and improvement in idling stability, according
to Mazda engineering, is achieved by both side intake and
exhaust ports with zero overlap.
Idle misfire and the resulting unburned fuel in the exhaust is the
main reason Mazda went to the side exhaust port. Unburned fuel
in the exhaust during idle is another way of saying high
hydrocarbon emissions.
I highly recommend downloading those tech papers from:
http://www.thecarricos.com/ACRE/
Paul Lamar
Paul, I have visited the carricos site which I appreciate very much.
However, it would help a lot if the file names indicated the
contents. So far I have downloaded a couple of PDFs just to see
what they contained, but I have not located the PP information.
Jerry
I guess it is a bit obscure. Todd perhaps you can rename those
with the year of publishing in the file name as a code so
I can tell people which ones to down load.
Paul Lamar
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