Im planning on possibly doing a pp on my 7. i have s4 engine and turbo with 9.4.1 rotors. getting ready to tear down and build her up again and looking to go little more wild this time. i have a borg warner s3 .91 turbo and a Airesearch garrett tv7701. havnt decided witch turbo if either to use. but thats just a small bit of info to get the discussion started. id like to do peripheral ports intake, i have the milling, lathe, welding equipment and ability to do the work no problem. my questions and help needed are as follows. id like to use factory tb and possibly pipe from factory plenum to the ports but what about flow characteristics? does anyone have blueprints for building the intake? i have a place to flow bench but id really like some help with designs and detailed measurements. and also, how much blow by does pp have? would it be a waist to turbo?

 

P-ports have a lot of intake/exhaust overlap. Unless you're really going to race the car or want it to idle at 2k I wouldn't do it. There's a ton of guys that posted their full p-port specs. You might want to look up my one buddy Nate's thread (DelSlow) he posted dimensions in his build thread.

I can CNC your ports if you decide to farm out the work

 

I will be doin the work, That's no prob. I will check out his build. My big thing is I want to use factory tb and don't want to screw up intake velocity etc. The car will only be driven very occasionally maby 1 a month and will be raced at local track. Other than that just shows. I don't mind high idle and blow-by is an issue if boost is total waist, like if I only get usable boost for 1,000rpm. But ill look at ur buddys thread and do some studying. Thanks for the reply and deff keep this thread going. Any and all info helps and detailed, detailed, detailed

 

Ok so iv been doin tones more studying and will be doing much more the same. But so far turbo pp is completely doable and should turn out fine. Im not sure on pp tube size though, looks like approx 55mm? What does everyone think? And I plan to use factory uim and tb. I wana make lim to attach from pp tubes up to uim. But where should I place secondary injectors on the new lim? Basically what im wanting to do is 13b turbo with 9.4.1 rotors with pp and new lim and keep everything else stock for now.

 

You really shouldn't use any factory parts. A peripheral port will be far more drivable and livable with independent throttles mounted as close as possible to the engine. Running a plenum on a high overlap engine is a really good way to pull exhaust gases up into the intake manifold and basically make the engine run like crap at idle and low load.

Mazda SPEC idle speed on a peripheral port engine is 1000rpm. Ignore the internet knowledge.

Building the intake is trivial compared to constructing the engine. Just do it right, you'll be far happier.

 

I had a S4 TII UIM on that. The motor had 46mm port's and used factory steel 2mm 3piece apex seal's.

 

Peejay iv read alot on this subject and seen u right in the middle of it so ill deff put much thought into your advise. Also if everyone can handle not gettin **** if I start a bit of some debating here. But the more I question the more I learn. So wouldn't the incoming charge air under boost pressure keep exhaust gas from traveling into the intake? And wouldn't the added length of the intake manifold help the low end torque? Also wouldn't the factory tb flow plenty well enough especially with turbo to feed the pports? And last question (for now ) wouldn't the overlap be similar to a bridgy?

 

This seems a prime example of what I have been planning to do and a prime example to argue with the effects on engine performance. So how did yours run with this lim? How was idle and powerband?

 

just to take it point by point, if your boost pressure is higher than the exhaust backpressure, the exhaust gas won't come up into the intake stroke. think about it like this, on a P port, both ports flow very well AND are both open at the same time for a long time. normally there is vacuum in the intake and pressure in the exhaust, so exhaust gas will want to flow into the intake.

the length of the intake does change where the torque peak is, yes, and longer is generally lower. however its not so much the low rpm torque that is a problem its the high exhaust gas content in the intake stroke, its like a huge EGR valve. so its the misfiring that's the problem, any time you hear it go brap brap, it sounds cool, but its not going to drive very well

the factory TB does flow enough, but its 3 butterflies, and p port is 2 holes...

the overlap is similar to a bridge, although it depends on the size and shape of the ports.

 

So far this thread is turning out better than I hoped. But I still fail to see a problem with using factory tb? 3 holes in the tb vs 2 pports when factory u have 4 or 6 ports? I may be missing your point. Just to keep very clear and keep this thread to no flaming, I want the debating in order to help me and possibly others learn the rights, wrongs, pros, and cons and to help create a broader understanding. I know that idle will produce a heavy mis fire but wouldn't even very little throttle provide near no vacuum in the intake?

 

its easy to to take a 3 hole throttle and split it into 4 or 6 ports, but how do you take a 3 hole throttle and divide it into 2 ports?

3/2 isn't a round number.

or maybe the question is why would you take a three hole throttle and put it on 2 ports.

 

The factory throttle body actually does split off funny...

2 ports feed one plenum, the third feeds the other plenum.

Plenums is the key, and are something you really don't want on a high overlap engine that you want good drivability from.

If I were to do another peripheral port, instead of screwing around like I did, I'd make it so I could use common 50-52mm throttle bodies from some OEM application and work out how to pull two cables.

 

I can make 2 tbs and connect butterflies with rod but id just like to keep the uim and factory tb. Id like to know the pollution that it will cause in detail inside the factory uim.

 

Also I don't see the trouble with placing the 3 hole tb to the factory uim and fitting it to the pports by making the lim by combining the intake runners for the front rotor in the lim and the same for the rear rotor. I can easily see using this set up adding to misfire at idle and having to increase idle speed to compensate. I will prolly end up building both just to satisfy my mind haha but let's get some numbers down guys about the tech side of this

 

Well, suit yourself. But keep in mind that it's not just about idle speed as much as it is trivial things like trying to drive 30mph.

 

ok so im hoping someone has some detailed info because im studying to find the flaws in this design and so far it seems a pretty solid way to go. using the factory tb and uim and building the lim will retain the length of intake to help low-mid range torque and will reduce peak power at given rpm witch should help drivability. also if i lengthen the distance from the engine to the turbo then that should help the low pressure wave to pull fresh air from the intake. what do you think?

 

I don't think an S4 TII upper intake manifold will flow very well, And the intake flow will be funny, going through 3 throttleplates into two plenums into four runners, into two runners into the engine. It will probably work but I think in the time you've fabricated a lower intake manifold that will fit and go from 4 to 2 runners in a nicely fashion you could've also fabricated an entire manifold that fit's an universal 80mm or so single TB, which would work better. (Kind of like the way they did it here, just use 2 instead of 4 runners, and some premade bends to make the manifold sit on top of the engine, Fabricating Manifold)

A longer exhaust runner will not 'bandaid' your car into running right when there's a big peripheral port and crappy intake manifold. I think with a turbo PP engine you need to focus on intake pressure vs. exhaust pressure. It's quite common with a turbo engine to have an exhaust pressure that is a lot higher than the intake boost pressure. This is bad stuff for a PP engine. You'll want as little backpressure as possible, ideally about the same as the intake pressure or lower. A nicely flowing exhaust manifold, large exhaust housing, and proper wastegating are things that come to mind.

 

well we are lucky as Mazda has a graph from the 13B-MSP paper that has the number you seek, however their measurement is CO concentration (exhaust gas) in the intake stroke. i don't have a CO meter, and installing one would be kind of tricky.

Mazda found that a STOCK S5 (or is it FD?) engine has something like 3.0 CO in the intake stroke, the side ports on the -MSP engine allow it to run something like 2.0 CO in the intake, which lets them run leaner at idle without misfire.

with a P port, you're talking about going the other way and making it like 5.0 CO....

 

this is allong the lines of "try this instead of that" that i am looking for. i dont want to do 2 tb's and if adapting a single is the way to go then ill gladly do it. i know its a bit different but im wanting to incorporate as much factory as possible. i have full open exhaust at 2.5in. and the only real restriction is the turbo itself. my goal is to run the pport engine off factory computer with as little tune and mod as possible as a sort of testament that it can be done.

 

could possibly make a bung on the intake and fashion a way to attach meter to read? i have access to a CO meter and could measure. there has to be a magic formula to design this to at least get closer to 3.0.

 

does anyone have any mathematical formulas or equations to figure out diameter, length, etc. to design pports by? out of all my searching all im finding is trial and error and copies of other pports without thorough numbers. id really like some good concrete stuff to sit down and work out on paper to get a good start base line.

 

Dont no if you have read this topic or not but : https://www.rx7club.com/2nd-generati...l-port-948818/ But he has run a PP on a factory computer. Was running with the original S4 ecu, NA primaries and TII secondary injectors, And this was his manifold :

 

there is an SAE paper on the peripheral port design, but if you're just going to use the S4 intake, it doesn't really apply.

BTW not saying you can't use the S4 intake, we're just saying that there is a recipe for the P port and its straightforward, and doesn't use anything like an S4 intake

 

Great feedback guys! Thanks for the good info. Ill keep checking this thread regularly, so anymore info or talk will be appreciated. Soon as I start then ill start a new build thread