Has anybody ever done a 6 port motor that added a peripheral port with ITB's that opened around 6K with extra injectors? I've already got the 5th & 6th ports & VDI working precisley - something like extending the power curve with the extra ports & TB's & injectors? I was thinking of using lightened rotor assembly & oil mods for a high RPM motor. Trying to keep the hp line going diagonal all the way to 10K rpm's instead of flattenning at 6k or so while keeping low rpm power the same. Basically an 8 port motor. All rpm & load dependant. I understand the expense & complexity involved and would be looking to net around 300-350 hp NA. I've seen some semi-Peri-port or cross-port references but haven't seen any street applications. It seems a little hush-hush about this particular setup. Just P.M. me with details if you don't want any pubicity. I know there is alot of added complexity and the mods necessary are expensive for a 10k rpm motor, but it seems like an untapped area for us NA guys.

Ramses666

 

Ok... I'll just shut up now!!

Ramses666

 

unknown... lol... closest I had heard about someone doing that was similar (streetable) was GtoRX7 with his 3 rotor semi PP... ask him maybe?

 

Surely someone else has done something similar?!? Anyone?

Ramses666

 

That would be quite a set up.

 

Had the owner of a local rotary performance shop back in the mid 80's do a 4-port, P-port combination using a 6-valve progressive throttle on top of a custom manifold, on top of the throttle plate he mounted a modified Preditor Carb (hi tech at the time, was a variable venturi carb), he spent some time tuning it but claimed it had a smooth power curve and great throttle response, qualities needed for a good street car... saw the car run at two different auto-x events, ran a big diesel truck muffler on a short collected header, sounded fantastic and was crazy fast... have to look for the pics... I know it is not the 6-port combo your asking about, but this example and what I have played with I would say your project is sound and would like to hear what your results are...

 

ok... thats the kind of info I'm lookin' for. Very interesting. I was comparing the s4 & s5 LIM's and the s4 was a simpler design and would be useable with some modifications. Since I'm not using the ACV I was going to cut out those parts and add the port holes for the Peri-port. I am still considering wether or not to try to make some sort of rotary valve like the 5th & 6th ports or if the added throttlebody plates would be sufficient to keep the peri-ports closed. Vacuum is vacuum right? Perhaps using just the throttle body plates would draw in more air at low rpms. Since there would be no overlap of the exhaust port I shouldn't have any back-fire problems.

The other questions I'm working on are determining actual runner length needed and at what point should the runners "communicate" with each other to maximize velocity & also when should the added ports "communicate" with the stock 6 ports & should I create another plenum for this purpose.

Another idea I'm considering is exhaust scavenging to maintain velocity. It has been discussed that a true dual starts to lose performance when more port area is added to the intake and rpm's go up. I already have the RB RoadRace True dual setup and was thinking about cutting the front pipes from the pre-silencer and making a collector to go in its place. something like 2x2.5 to single x4 & then back to 2x2.5 into the dual chamber pre-silencer. kind of an x-pipe but with a 4in diameter and 4 or 5 inches in length of common area. Maybe it would be better to keep the collector dia. smaller to keep the velocity higher and just make a basic x-pipe setup.

Of course there are numerous other issues - ECU, Fuel system capacity, High RPM engine building, drive train issues, engine monitoring & tuning, but these are just basic Rotary issues I can deal with.

Ramses666

 

OK, Few things to consider... runner length basics... short ones promote better low end torque (short runners have less volume therfore less mass of air and we know that the smaller the mass the faster it can accelerate, so we can use this to fill the chamber better at low rpm), best high rpm chamber filling occur with longer ones (again it has to do with air mass and now add it's momentum, in this case artifically boosting pressure at the port end of the runner when the rotor seals it). So the primary runners need to be the shortest, the secondary ports are now considered medium length, and the p-ports should be the longest in this application... this is the first step in widening the power band.

Now to make this work, we need to flow air down the correct runner at the right time, so each runner pair needs a set of throttling valves. If we simply ran an open plenum (like the stock FI manifold, all runners into one common area), then the air would find the easiest path to the chamber - which would be for the most part the p-port runner - and the others would only have a minimal effect and then why bother.
Side note : Mazda spent a lot of R&D time developing the thier variable tuned runner design to work so as to maximize the cross charging effect that can occure with the open plenum design, so unless you have the background or funds we will need to stay old school and not worry about having the runners "communicate" with each other.
As far as trying to get the 5-6 port sleeves to operate, at this point the new 6 valve throttle plate takes over the basic idea and function and the sleeve actuation would just add redundancy and complexity to the setup. Now up to this point we have developed a specific runner set for the idle/low, mid, and high rpm parts of the power band, and can, using the progressive throttle valve, control when each starts to work...so

Let's talk port timing, now to avoid writing a book I will hit basics... we want to try to widen the power band, something that is lost when we use conventional thinking and start changing port timing and sizes , so we will need to keep the stock port configuration and just improve efficeincy by smoothing out and balancing the runners in the iron housings, remembering that the p-port will now take care of the overal high speed volume requirements we will need.
Now the p-port timing - if you are using pre-made P-port housings then you are stuck and the system will not work as well as it could, if you are into DIY then your goal will be to only advance port timing about half to 3/4's as much as a good b-port timing, remember, just adding a p-port with stock timing alone increased your overall chamber filling ability just because of added flow, so adding just a little more advance port timing than stock will give even better filling at the higher RPM, but the more overlap you have the more problems you will have with streetable exhaust systems causing contamination of the fresh intake charge... I think I kept every thing straight and covered all the points so far... Were abouts in Florida do you hang out?

 

Hey! Thanks for the informative reply. I'm in Ft. pierce Fl. About the port timing... I was considering a small DIY PP (3/4 or 7/8 inch diameter) that would basically split the port timing between the existing secondary & auxilliary while staying about the same as the primaries. I was thinking this would help with the cross port induction of the intake charge through the secondaries & aux's.

My real question about port length is what is actually measured? I would think that the measurement would be from the actual port opening in the housing or iron to the point where the runner from one rotor joins with the runner from the other rotor regardless of throttle plates at WOT. For instance in the S5 NA there is a small plenum after the throttle body. This would be where the runner length effectively ends for the individual runners because the flow splits. Now the VDI changes the length & volume by allowing more air to flow through different connecting passages. I was considering mounting my extra throttle bodies for my added ports as close to the LIM as possible, but keeping their individual runners separated until the are joined up near the existing throttle body using a custom made elbow job. Basically a pair of velocity stacks.

I'm wondering a good ball park figure for the total length needed. Should I get out a degree wheel and figure out a proposed port area & timing and then an arbitrary runner length & volume. The problem is I'm in somewhat uncharted territory. There doesn't seem to be any real information available. Perhaps if I knew what I had for port area, runner length & volume for the S5 NA for the primary, secondary & auxilliary & VDI then I could perhaps extrapolate a good starting point for an added set of ports & runners.

Oh yeah... I think I confused you a little. I want to ADD two seperate throttlebodies - one for each PP while keeping the stock setup intact. Anyway thanks for the help.

Ramses666