Rpm wise, what's your definition of low end? Blow 3k, PP's don't cruise well for dailey driving.

 

i just want some power maybe to 3000 or 2500 and its for a race car of my buddys so we want some grunt coming out of the corners

 

^ I can tell your not use to these forums. My above question wasn't directed at you. It was to Ultimate. Anyways, you and I think alike. The best thing for you to do is to build as many prototypes as possible to see what works best. It also really really helps to be a 3 dimensional thinker. Having a vision is one thing, taking that vision and making it work in your mind is a whole different story. You can go crazy just thinking about the little nuisances that will take place. I've personally grind-ed my head for the past 4yrs thinking of a way to accomplish this same idea. I'm about 95% ready to actually start fabricating the set-up. I just got to finish my 20b 1st. Once you've gotten the basic design done, now you have to find a way to fuel the beast and find a suitable ecu that will control everything. Also, don't forget about your exhaust set-up all have to comply with your intake set-up to work as a complete unit. Lastly your safeguards need to be well engineered. Good luck though. This ain't no armature project.

 

I say... GEt some really short gearing=P ANd you will have plenty of exit accel.=D

 

The idea that peripheral port intake rotaries have less low end power is completely FALSE.

I am right now looking at a dyno chart of the NSU KKM-502 engine that has a plot for both peripheral port version and dual side port version.

From 1,000rpm to 6,000rpm there is no point where the side intake port engine made more power. NSU chose to put the peripheral port engine into production for this reason.


Now, NSU peripheral ports were small compared to modern Mazda racing peripheral ports as the dyno chart shows the peripheral port engine only made 30% more power than the side port port engine at 6,000rpm and the peripheral ports closed at 50 Deg after (like Mazda turbo sideports). Max torque @3,500rpm dropping 20% by 6,000rpm.

The reason that Mazda chose side intake ports for their production engine is that the peripheral port engines could not be made to run smoothly at low rpms and under light load because of all the overlap. NSU simply put a torque converter in front of the clutch in their production cars to avoid the "******" associated with light load peripheral port driving.


Obviously, peripheral port engines don't ALWAYS make more low rpm power.

Now I am looking at two dyno charts both of a Curtis Wright IRC-6 rotary one with peripheral port intake and one with side intake ports. In this engine the periperal ports don't make more power until 4,500rpm and it only make 20% more power.

Curtis Wright was primarily developing side ports, but gave another try at a high speed engine (RCI-6) based on the the IRC-6 with peripheral ports and their dyno shows it now made more power from just over 3,000rpm and made 50% more power now than the earlier sideport IRC-6. Much more like a modern Mazda racing peripheral port.

So, if you want the most power from 2,500rpm up and max high rpm power you will want to go with a small (round) peripheral port that closes in the ~60 deg after range.

Once you have your small peripheral port you can add sideports that are actuated to open later form more port area at high rpms so the torque doesn't drop off so hard. This is possible because the sideports can be completely closed (rotor side blocks chambers) while peripheral ports are always open (apex seal cannot block chambers when over peripheral port).

In this scenario you would use 6 port side housings and fill the 4 normal ports as usual with a peripheral port but leave the auxiliary ports/sleeves/actuators intact for the later 80 deg after closing for high rpm power.

Aim the primary peripheral port trajectory carefully and inject all your fuel in the primary peripheral port so that the charge density is higher than the sideports and you will get a siphon effect putting a low pressure area at the sideports.

 

The bridge will not help it. You can not stop air from going around the apex seal on a p-port. Move your green line around the bridge rather then around the apex seal. The same thing happens. As long as there is a pressure differential between each chamber, and at that point there is, air will find a way to flow to the point of least restriction. That means around your bridge. You CAN NOT seal it! It's not about airflow through the runner. That's irrelevant. It's about equalizing pressure between chambers on each side of the apex seal.

 

MAke a low reving p-port=P JUst make that port towards the top of the engine some and wala! low end but no top end?

 

Way Off

 

i may have not explained it all the way clearly, the two sections of the p-port are seperate they are sealed off by a slide throttle plate on the far side( away from the rotor housing) so the are like two compleatly seperate ports till the throttle plate opens!

pic#1 closed

pic#2 1/2 closed

pic#3 open

 

The reversion problem is because as the apex seal goes over the second later closing peripheral port any charge being compressed will leak past the apex seal (since there is no rotor housing where the p-port is) right to the other side of the apex seal where the next rotor chamber is at lower pressure.

With the auxiliary later closing side port there is no reversion problem with the rotating sleeve or even just the European style manifold runner butterfly as when the sideseal crosses the port the charge being compressed CAN leak to the other side of the sideseal, BUT is trapped in the rotor flank area and kept from going to the next low pressure rotor chamber by the OTHER side seal that stays on the sidehousing without crossing the port until it is closed.

Now your two peripheral port idea does help low end/idle smoothness some by keeping the runner cross section down to keep velocity up and so was used by NSU and other companies made peripheral port production engines.

So, this is why I suggested a small early closing p-port for max bottom end and then a late closing sideport to prop the top end up.

Or, you could do two parallel peripheral ports in each rotor housing with the same early (50-60 after) closing and just use one at lower rpm for increased velocity and both at high rpm for better flow. In this scenario a later closing sideport may not increase top end power at all due to its flow inefficiencies.

Now on the exhaust side you will want to keep the peripheral exhaust port small for low end power. To aid top end power you could use renisis sideport exhaust housings for more area on the high end and have them closed off with a swingvalve wastegate at lower rpms. So, renisis sidehousings/rotors and early 13B rotor housings for the small exhaust and water seal grooves with a small early closing peripheral intake port.

 

The only way for a p-port to not have leakage around the apex seal tip is for the port to be no taller than the apex seal width. You get leakage through the leading spark plug hole! The reason why it doesn't matter there is because pressure on each side of the apex seal is roughly equal at that location. However look at the trailing spark plug hole. It's tiny for this reason. Pressures on each side of the apex seal are very different here. If the trailing plug hole were any larger, air would bleed off of the front of the apex seal and move into the following chamber.

If you have ANY leakage point where you want to put a p-port, you will get the chamber in it's compression stage to bleed off somewhat into the following chamber. The larger the hole, the worse it gets. Fortunately the higher your rpms get the less and less of an issue this becomes. If you have no problem allowing this at lower rpms and loads, then you should have no problem just going full p-port or bridge and you can not keep the advantages of a side port engine and still have a p-port. It can not be done! Your idea will not work. It'll lessen the effect but it'll also lessen the benefit of having a p-port in the first place.

 

well it never hurts to test new ideas and revise them as you go hell thats how most everything got the way it is now! if if wasn't for crazy ideas and testing there would be no wankel at all!!!! and as your sig says "if you aren't testing, you are guessing" testing is the only 100% correct answer.

 

I like the way your thinking! the idea of two p-ports is great i will probly work that in to my final model for testing! thanks


I knew if i posted this that lots of people would get to thinking!

 

personally, i just don't get why some people insist on skating uphill just to be different. i mean imagine all the semi-peripheral 39B Renesis engines people would have out there if development was THAT easy.

with that said, here's more wood for the fire ...

maybe you could try hacking up Renesis rotor housings since for this purpose they would essentially be blanks. that way you can figure out your own timing, then size and cut the ports yourself. of course, you'd have to sleeve it and block whatever water passages, but doable if you have the machining skills, no?

it might help you decrease some of the overlap issues while maintaining useable power.

 

hummmm! i hadn't had that thought yet! that would be a better idea so the exhaust timing could also be changed slightly. that would give me more room to play

 

anyone know where to get a 20b center section? have found lots of e-shafts but not the centers

 

I'm all for testing new ideas. Sadly though this idea isn't new and has in fact been tested. How many do we see on the roads?