I'm kindof wondering what the buzz on it is?

 

The general feeling I see and hear is that its a neat idea, but the payoff is not enough for the amount of work involved.

The short list is:
1. The intake manifold becomes rather tricky to mount and design.
2. Swirl. One of the great failings of the side ports is the dircetional changes the intake charge makes as it enters the chamber. As long as those side ports are there that odd flow will hurt a peripheral port.
3. You can get as much streetability and power with a regular port (be it street, race, bridge, or peripheral) for less initial cost and less tuning headache.

 

For a race only motor it would be great but street motor I wouldn't even consider it. The intake is easy part you can get it from http://kgparts.com/jay-tech.htm I believe it's around $550 for it. It is an expensive but different motor combination to put together and hey that's why we build rotarys, to be different. There's a car in Puerto Rico that has been successful with this setup it's a Toyota Starlet that's 3/4 chassis and runs consistant 7.6 1/4 mile times. And there quite a few others coming out with semi-periferal nitrous setups. And everyone is saying that they are a bitch to tune. So unless you have great tuning skills or lots of money to pay someone I wouldn't even consider it. https://www.rx7club.com/showthread.p...lleana+starlet

 

Look at the paper, "recent-tech84-7-11", don't remember where it is hosted but a search will probably find it. It shows a study where intake ports are analyst. It shows that a combination port, side and peripheral, gives best performance at mid to high engine speeds. It seems a good compromise of only top end of the PP and good low end of the SP. That paper is for NA engines but I am sure it will have similar effects with a turbo.

 

The article is at: http://www.thecarricos.com/ACRE/

 

What about for a NA application? I would love to build a semi PP 4 rotor. You could engineer the LIM to have a valving system in the PP's that close it off during low rpm operation. Then at the higher rpm's the valves open. This should allow the engine to have a normal idle for street applications and be a beast in the higher range. Basically the PP's would function like the 6th ports of the NA version of the S4 and S5.

 

That will cost a bit.

 

Anything 4 rotor wise would be expensive.



If I ever hit the lottery, I'll build this engine and stick it in one of these:

 

Yeah that is a great idea now I wish someone would do it. I've got a set of 13BRE plates that I'm saving to do a n/a semi-periferal motor with. Currently building a turbo motor but I love n/a rotarys just something about an all motor.

 

LOL, shm21284 has now decided to do his graduate thesis on SP ports for street car usage. He's come up some really "complex" but awesome intake system so I'm hoping to see more about it later.

 

I have thougth about it many times, and I am still considering. There are many Japanese tuners that have them and use them. Most are like the KGparts manfiold, although is a stock replacement so you can use the oem upper intake manfoild etc. Then there are a few that make stock replacement that use the primary ports only along with the peripherial ports. The latter set ups I have seen more NAs than Turbo.

Along with that I have seen dyno sheets with as much as 380 rwhp at 8k rpm and being fully streetable, thats using 9.7:1 rotors, I was going to use the 10:1. From what I read using 9.7 over 9.4 or 10 over 97. will yeild approx 10-15% more power.

 

You apparently glanced at it but didn't pay attention.

The "combi port" is a bridge port.

 

I drove a half bridged motor for almost a year and its definately kick *** !! , all the Hype you read about having little or no low end is just that , plain hupe ! . The "lack" of low end torque cost me a few drive train parts and thats at only 10 psi boost ! , be warned though , you mileage goes to hell !.
I am presently finishing up my "new" semi pp motor , I went the extra and go the Pro-Jay parts (very good quality and worth every cent) , I am also going with twin t3/4 GTR turbos and a new and different ECU , I'll be sure to post my results when I'm done.

 

What exactally is a semi-p port? I know what a p-port is and don't see how one could halfway do it.

 

Semi PP, is a ported engine, with "Tiny" pp ports (when compared to the regular PP engine).

 

AND with those tiny peripheral ports you keep the existing side ports instead of filling them in as with a regular peripheral port.

 

Here's a question, how's the throttle setup controlled? It would make alot of sense to open the throttle for the SP ports at higher RPMs only, right?

 

The drawings looks like a bridge port that is extended into the rotor housings. So the opening and closing timing is determined by the Apex seal. The opening and closing times of the P-port mentioend fit a true peripheral port, though. A true peripheral port with a straight intake runner yields better results than a mega bridge that uses the side port intake runner. There wouldn't be much difference interms of timing you can achieve but the flow characteristic of a true Pport should be superior to a mega bridge. So I assume that a combination port using a true Pport would flow better as well. I hear some noise about the side ports interfering with the Pport....not sure if this is based on first hand knowledge or if it is just a theory. I guess we will find out....

CW

 

Actually, it would make more sense the other way around. The timing the bridge or Pport accomplishes improves the air intake of the engine at higher rpms.

CW

 

But peripheral ports work better than side ports down low as well.

If you really wanted a "bastard" (side and peripheral) arrangement, the thing to do would seem to be controlling the peripheral ports by vacuum - over Z manifold vacuum the engine runs only on the side ports. That way you could realize as much of the advantage of side ports (smooth efficiency at low load) as you could get despite still having the peripheral port there fouling things up. The switching valve should be as close to the rotor surface as possible.

 

That's why I said ported engine with tiny PP.

 

How about a holley style manifold, and a carb\efi 4 barrel TB, that opens the secondary at a specific rpms?

 

That would put the secondary opening too far away from where you'd ideally want it to be.

You really wouldn't want the opening to be RPM specific, but load (manifold vacuum) specific instead. Side ports are good for two things: running smoothly at low load, and this:



If you're at low load (at ANY RPM) then you want to be only on the side ports, but if you are at high load (at ANY RPM) then you want to be on the peripheral port.

Hmm... here's an idea. A switching flapper similar to HVAC controls, that will switch intake flow from all-sides to all-peripheral depending on manifold vacuum.

Or, here's a better idea... screw the complexity and the compromise and just use the side ports as epoxy storage.

 

Thats what it always comes down to. If you want to take the time and/or spend the money you can innovate and make some really intersting power combonations. If you can't then you have to stand on the shoulders of geniuses and simply git 'er done.

 

It has been suggested to me at low RPM that having a actuated semi-PP would result in exhaust gases escaping around the apex seal at the closed periperhal ports at low RPMs and cause dilution, just like in a full PP engine. In other words, even with the peripheral port closed there would still be overlap. Thoughts?

How important is it that the valve be close to the rotor surface and what would the ramifications be if it wasn't particularly close?