VDI and 5/6port question.. need SMART people
 

If you wire the ports open (like with a ziptie or something) that doesnt mean the VDI valve is open does it? It seems like wiring the ports open wont do shit unless the VDI valve is open as well? And I dont understand how you can "remove" the 5/6th ports.. ddub said he removed his and it helped his high end, I dont see how this is possible either.. Wouldnt removing them be the same as them being stuck shut? plz help :(

help?

Everything that made me take mine out I learned in this thread https://www.rx7club.com/showthread.p...&highlight=6pi

But basically... take your lower intake manifold out, the actuators are on there and it should be visible as to how they are held on (screws if I remember correctly). Take the actuators off and slip them out of the ports, since they will have rods in there that move the sleeves to open/close the pathway for air in the ports. Take the sleeves out after this, then find something to block the newly made holes in your intake manifold (where the sleeves came out of/where the actuators were held against). To block mine I tapped the holes and put bolts in, but you can do whatever pleases you (like a small custom blockoff plate or something). Hope that helped.

Do NOT wire the VDI actuator open.

What happens if u do

And thanks dDub for the reply

Well isn't the VDI the "fake boost" thing that s5's have? The thing that goes after the tb/dynamic chamber inside the upper intake manifold? In that case it really doesn't have anything to do with the 5th/6th ports if I'm not mistaken. It's just another thing to help with hp creating the 1/2psi or whatever it is of boost.

Anyways, wiring the VDI open would seem like a bad idea since it needs to be regulated most likely.

I think a properly working 5th/6th ports would be the best application for your project. You got them working, use it to your advantage.

Why? What reasoning do you have? As you mod an n/a engine more and more, those sleeves become a restriction rather than helping. Plus, a mildly/heavily modded n/a block will show improvements in high end power from removing them, and if you're dragging or autocrossing that's all you'll ever see. Sure you *could* lose a little low end (on less modded engines) but it's really not that big of a deal. I ripped mine out and didnt notice a single change in low end power, my high end however became smoother and pulled harder.

dDub, you have a damn nice car there, nice mods list and such.
Anyways, ill probably pull my manifold tomorrow and port it, and remove the sleeves after all my reasearch tonight, thanks all for the help.

Thanks :D

And yah, no problem, good luck with it. Porting was so much, uhm "fun" I guess :p: I did it with a saw drill bit and a weak ass drill so it took FOREVER. But I was really happy with the outcome. I ported my intake manifolds, did the TB mod, and pulled the sleeves and everything all at the same time and was VERY happy with the outcome.

I might use a dremel, or a drum sander drill bit.. i have the saw drill, i used it to port my TB, and im not too happy with how smooth it turned out. Unless i go incredibly slow, it really roughs things up it seems like.. maybe it was the drill though

Yah I'd use a dremel, may not be the fastest but it's definitely easier on the hands :D And its way smoother. Yah at first when I was porting the saw drill bit was a little troublesome, but I kinda came up with my own methods to make sure it was smooth and it seemed to work, however still took forever and killed my hands.

This is for your superchrged engine right? There's only one way to find out if the 6PI and VDI systems should be kept, and that's test it.

You need to dyno the engine twice; first with the auxiliary ports closed and then with them open. You'll then have two power curves to compare. On a stock engine the power will be higher at low rpm with the ports closed, and higher at high rpm with the ports open. The crossover point of the two curves is the rpm you open the ports at.

On a supercharged engine the cross over point will either be lower or not there at all, with the open ports being more powerful right from low revs. In that case you wire them open or remove the sleeves altogether. But if the two lines cross over each other, then you should keep the 6PI system operational if you want the best performance from the engine.

You then perform the same process with the VDI open and closed. This one's much harder to predict, as it depends entirely on the acoustic tuning of the intake manifold. But again, if the two lines cross over each other, then you should keep the VDI system operational if you want the best performance.

guessing is as close as you will come to knowing without dyno'ing in the manner stated by NZvert. If i were to *guess* i would say that your performance with a blower would be best with the sleeves wired open or removed and the vdi wired open. the vdi i think is mostly to help the intake flow characteristics of an NA engine. also...even if working ports and vdi do help minimally on the low end, i think i might ditch them in a supercharging project just to clean up the junk in the engine bay and get rid of the airpump that sits in the way of where you'd put the blower :)

This is my theory, but NZ does have a good point... Ill definetly be using the dyno though, since there is one like 5 mins from my house, 40bones/hr.

That's it? Where is that? That could be very helpful to me :D

I live in walla walla now. Its at the Walla Walla College on campus :S, Lol sorry, its about a 5 hour drive for you i think

Wouldn't the VDI and 6PI still be benificial on a SC set-up? I don't quite understand why they wouldn't work.

dDub said the 6p sleeves are very restrictive to anything other than a stock or mildly modified setup (or something along those lines) I dont think mazda counted on people putting a forc SC on their FC's. The '6pi setup is mostly beneficial to "stockish" cars', is what ive been hearing the last couple days.

Yep exactly, plus if you look at the how-to that Aaron Cake did on his turboing an n/a, he took his actuators out as well ;)

the vdi is closed at low rpms so you have long runners to your ports to increase the intake velocity with minimal turbulence. at higher rpm when the engine needs more air the vdi opens and connects the intake runners together so they can build pressure off of each other. at low rpm an open vdi would make your air more turbulent and steal some of your power from you vs at high end where the engine is sucking harder and this matters less. this is all based on an engine that is SUCKING its air in, with the blower blowing air in you would then want as little restriction as possible.

as for your "why wouldn't they work?" well, they would work fine, you would see a nice increase in power when they opened up i would imagine. however, i think you would be making more power further down the rpm range if they were open already. this is of course, all based on conjecture as i have not actually supercharged and dyno'd a car. it will be really interesting to see the results Dezerte gets when he dyno's the car. make sure you post those up man :)

i just purchased my 86 rx-7 about two weeks ago and started purchasing some minor mods but this is very interesting to me and would like to find out what exactly what the 5/6th porting is and how you do it. it would be greatly appreciated

Yo, I up loaded this on my personal webspace just for you :o:: Intake and Fuel systems
This is the fuel/intake system of the shop manual, its for the 89-91, but its very similar to your car.. maybe even the same? Anyways, after you download it and open it go to the "6 port induction" section (6pi) and read about the 5/6th ports and all the rest of that junk, hope this helps
-Josh

Edit* here is some more info on how to check if your 5/6th ports are working, and what to do if they arent: http://www.aaroncake.net/RX-7/tech1.htm
Its a page done by a forum member "aaron cake"

And if you have trouble finding the "5th/6th ports" in the Factory Service Manual, that's because the correct name for them is the auxiliary ports. ;)