I usually keep my mouth shut when it comes to P port discussions.  I  agree with everything Bill has written with one exception.  I doubt  the big p ports are advantageous at our RPM.  A 1.5" i.d. port will  flow  7500 rpm, no problem.  The smaller ports are easier to time  (less overlap) and the smaller dia.  intake tubes are much easier to  fit.
jerry





On Jun 18, 2007, at 1:01 PM, Richard Sohn wrote:

Bill,

AMEN to all.

Richard Sohn
N2071U
----- Original Message ----- From: <wrjjrs@aol.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Monday, June 18, 2007 11:12 AM
Subject: [FlyRotary] Re: Fw: Different Rotary Port configurations




Guys,
Lets cut to the chase. The P-port rotary will idle fine. The original
12As were p-port. Lots of the NSU wankels were p-port. John Deere and
MB C111 engines were p-port. There was no comment that these engines
didn't idle. Perhaps not as smoothly as the side port engines, but  idle
none the less. The P-port makes the most power, period. Mazda wouldn't
have used the P-port only on their LeMans engine if combination ports
would have worked better. Don't think for a second they didn't try
other configurations either. They used the far trailing plug to  improve
efficiency less than 2%. Richard's work showed no improvement to power
with the side port/p-port combo. Anywhere but idle my guess would be
that the inrush from the p-port probably causes minimal flow in the
side ports. The p-port is open much sooner and flow is underway by the
time the side port opens. If we had a source for finished p-port
housings that cost the same as the standard housings we would all be
using them and the discussion would cease and we would move on to  other
subjects. For aircraft use the big p-port is for most cases the best
possible solution. We can improve on minor details, but not much. The
simpler manifolding and more compact package when using fewer tubes  for
the intake are all pluses for the p-port. We don't have car low RPM
issues to worry about. If a good source of the Mazda racing p-port
housings was available for the same price as standard housings I'd  have
3 on order right now. (20B remember)
Bill Jepson




Well, Mark - perhaps in the future



Only so much time and so many things that would be fun to try. IF I
interpret the charts correctly the P + S type intake configuration
appears to provide much more intake port area than either the P or S
type along. Makes sense - if you have twice as many intakes it has
more area. Supposedly the P+S overcomes the low rpm idle problem of
the PP alone.



But, for aircraft usage, I think Richard is on the money, you don't
really spend much time at idle in aircraft usage and I idle above 1600
rpm in any case, so who cares {:>) - just go with the P port.



However, I am intrigued by the large intake area that the P + S
configuration has over even the PP alone and what that might potent
for POWER! More Power, Scotty!!!!!



Saw some information on the Renesis in an SAE paper that indicates the
six port (They call it the HIGH POWER Renesis) produces 40% more power
than the standard 13B. They did not make a comparison to the 4 port
Renesis but presumably it produces less than the six port Renesis but
more than the older 13B. They also didn't specify the rpm point that
occurred, but I assume it must be near its maximum. Also, its not
clear if this figure was based on the earlier 250 HP claim for the
Renesis by Mazda or the later adjusted 237 HP claim (actually I'd take
either one) .



The intake configuration and operation on the six port is quite
involved, but they do make use of the Dynamic Effect. They call it the
Sequential Dynamic Air Intake System (S-DAIS). Since there is no
intake/exhaust port overlap in the Renesis, they appear to make use of
the "A" pulse which is the pressure wave created when the high  velocity
air in the intake slams into the closing port and bounced back down  the
manifold. They then have several valves that activate at different
rpm/air flow situations that control the sequential activation of
elements of the S-DAIS.



As well as the "A" pulse, the older NA 13B DEI also used the stronger
"B" pulse created when the intake opened releasing a burst of the
trapped exhaust gas residue to create a power shock wave which raised
the manifold pressure at the second rotor's intake. But, since there
is no intake/exhaust overlap with the Renesis side ports, it would
appear that only the "A" pulse is used to enhance power.



Ed






----- Original Message -----

From: Mark Steitle

To: Rotary motors in aircraft

Sent: Monday, June 18, 2007 9:12 AM

Subject: [FlyRotary] Re: Fw: Different Rotary Port configurations




Thanks Richard for the clarification.


Mark S.

(Looks like I should have typed a little faster.)


On 6/18/07, Mark Steitle <msteitle@gmail.com> wrote:

Well Ed,

It looks like you've got yourself a new intake project. Didn't Richard
Sohn try running side and peripheral intake porting on his one rotor?
I vaguely remember him mentioning it and that he abandoned the idea. I
think it had something to do with the complexity of the dual runners
and that he was satisfied with the idle characteristics of the p-port?
Maybe Richard can comment?



Mark S.



On 6/17/07, Ed Anderson <eanderson@carolina.rr.com > wrote:


Ok, here's the answer to my question. The second image shows a three
barrel carb with the primary going to two side intake ports and the
secondary going to the Peripheral ports. Interesting concept.



Ed


----- Original Message -----
From: Ed Anderson

To: Rotary motors in aircraft

Sent: Sunday, June 17, 2007 10:15 PM

Subject: Different Rotary Port configurations





Ok, getting a bit quite again. Here is something that some of you may
find interesting. Its a graph comparing the possible different port
configurations for the Rotary engine.

The top graph shows the intake and exhaust port opening for a engine
with a peripheral intake and peripheral exhaust - such as a 13B which
has been converted to a PP intake.



The trapezoidal shapes show the port area. For example on the first
graph the first rectangular area entitled PORT shows the Peripheral
exhaust port open at 63Deg ATDC. There are two trapezoid areas shown
for the Peripheral intake. A "P" which I presume stands for Primary
and a much larger P+S which I presumes stands for a combined primary
and Secondary port. Although, I do not ever recall a PP with two tubes
one for primary and one for secondary. So there may be another
explanation.



The second graph is our traditional 13B with sideport intake and
peripheral port exhaust. Here the intake timing for the intake is that
of the NA 13B although it shows the intake opening a bit later than  the
stock 13B but closing at the stock 40 deg ABDC.



If you look at the area under the first graphs "P" trapezoid it  appears
to be open much longer than the P for the side port intake (2nd  graph),
but the trapezoid is not as high. Wonder what that signifies? Open
longer but not as large a port area?



Anyhow, thought some of you might find it interesting.





Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
http://members.cox.net/rogersda/rotary/configs.htm#N494BW
http://www.dmack.net/mazda/index.html



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