A few days ago, going through my p port stuff, I ran across a
drawing
I did comparing my p ports with the Leman' ports. Since I had a
housing to measure and access to a height gage, I added Paul's p
port. The drawing requires studying for a minute to get
oriented. It
shows the port's locations referenced from the horizontal center
line
of the housing. You will appreciate this when you are preparing to
hit your housing with the hole saw. If you want to do the math you
(Paul and Rolf and a few others who are able) can come up intake
opening in terms of degrees. it satisfies me to be able to make
some
obvious comparisons:
1. The Leman's port opens and closes a little earlier than Paul's.
2. The leman's port is slightly larger then Paul's. Both are much
larger than mine.
3. All three ports close at nearly the same time with Paul's and
Mine being virtually identical.
4. My port opens quite a bit later than either the Leman's or Pauls.
I think Paul's port will perform very much like the Leman's port,
which was the goal. It has a little less overlap and a little less
area, both of which I think are beneficial at our rpms. Paul, would
probably argue that bigger is better.
My port will perform more like the Power Sport port which
peaked at
215hp just over 6000 rpm (I forget the exact number) It probably
will do significantly better at 7500 rpm but we won't know until it
is tested. In theory, more rpm favors the larger ports but remember
that 7500 rpm is nothing in the world of P Ports. Paul's port is
probably good to 11,000 rpm or more. I think mine would run out of
power above 8,000/8500 rpm.
When you look at all three ports lined up lined this, it is pretty
clear that timing is not that critical or even that optional. The
ports have to be located about where they are. The centers of the
three ports are within .250 in. of each other. So if you really
feel like "engineering" your p port, then go for it. Just stay with
in the limits of the drawing. :)
Soon we will have a few p ports running and then the fine tuning
and the fun can begin. Jerry
Jerry,
We don't agree on everything that's for sure, but here's an area
we do agree
on - we won't talk on port sizes.
If I could just add a couple of things in this discussion-
1. Paul's find on the German document which showed the initial P-Port
opening, did allow some air to escape to the exhaust and
confirmed that this
was a good thing as it helped evacuate the exhaust( I assume at
low RPM/
Idle), helped to stop exhaust entering the inlet and I guess help any
remaining fuel burn up in the exhaust.
This is all good provided you delay the fuel until the exhaust
closes - as
in Tracy's ECU.
I still believe the PP can be .5" different ( one from another)
and still be
fine.
I was wondering why you were being so pedantic, but it seems you
were just
trying to clearly demonstrate the different ports.
George (down under)
Mixing exhaust and intake can't be good regardless of what the
German's found. Unless the injectors are setting right on the port,
fuel will lost into the exhaust regardless of injector timing. With
remote injectors (anything more than a few inches from the port) the
intake tubes will always contain fuel I think. Of course, what do I
know? Dummies have opinions about everything. Jerry
It all depends on the instantaneous pressures and gas velocities
Jerry. Sometimes the pressure is higher on the exhaust side
and sometimes the pressure is higher on the intake side
due to organ pipe effects. At high RPM the gas velocities
are so high (up to Mach .4) the mixing, if any, is insignificant.
Think of a jet engine. There is no physical barrier between
the compressor and the combustor yet the exhaust gas usually
does NOT flow forward to the compressor. (Yes I know about
compressor stalls.)
The p-port rotary is akin to a jet engine despite being
an intermittent combustion engine. It is the most
continuous intermittent combustion engine I can think of.
Actually I can think of a better one. A pulse jet used
in German buzz bombs in WW II.
If one injects the fuel directly into the rotary compression
chamber after the intake port closes no fuel goes directly
out the exhaust with out first getting a chance to burn in
the combustion chamber.
Ironically the BSFC is no better (so far) than a p-port with
the injectors on the open end of the pipes.
A lot of this stuff has been tried by CW, Mercedes, John Deere,
Rotary Power International and Mazda and the results have been
published in dozens of technical papers. After 40 years
of experimenting the best they came up with is .47 BSFC.
Exactly the same as the P-port Lemans engine.
One of the problems is the low compression ratio of the buzz bomb
engine, the rotary and the jet engine. If a way can be found
to increase the compression ratio with out sucking a lot of
power out of the power section than the BSFC will get better.
Organ pipe tuning helps. P-ports help because they are aerodynamically
efficient. As does a turbo charger. The more efficient
the better. The compressor section, internal or external, stores
some of the energy used to compress the air in the form of heat.
If this heat energy can be retained (no inter cooler) than
the BSFC will be better. The diesel engine is a good example.
So Doug, as I said, if you must burn alcohol, try a turbo charger
sans inter cooler and inject the alcohol directly into the
compression chamber to cool the charge and prevent detonation.
Detonation is more or less the modus operandi of the diesel
engine :)
Now to recover some of the other half of the energy in a pound of
fuel going out the exhaust we need to develop the turbo compound
rotary. If I can finish this silly house project I am going to get
back on it.
Paul Lamar ...No rotor no motor.
For sure, direct injection and turbo compounding would change
everything. But these are just dreams at this time. Jerry
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