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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