Samps

I'm planning on removing the air pump and sleeves and I need to know what to do about the VDI. I searched everywhere and nobody has ever actualy explained how and where the VDI solenoid is and how to wire it or control it. I read that leaving it on high is the best bet but I don't know how to put it on high or low or even where the damn thing is. I wish It could still work like it does now but I don't see that happening.

NCsublime

Do a search for "secondary ports" or "six ports" or "5th and 6th ports" and you are bound to find a myriad of information. There have been several threads regarding this. The two dashpots that control the secondary ports are on the intake (passenger) side of the engine, directly above and on each side of the exhaust manifold. I've heard some describe them as looking like "mushrooms." They will each have a small vac line running into them from below. On top there will be a rod mechanism that is supposed to be moved with vaccuum pressure. If you pull off the end of the vac line that does NOT connect to the dashpot ( I beleive it goes directly above it to a group of vac lines) so that there is one end connected to the dashpot, and one end that is not connected to anything, then you can blow into that vac line (it will be quite short, so you may need to use another line to make it long enough to blow into). When you blow into the line (you may need to blow quite hard, especially if the mechanism has been stuck), the mechanism should move and the rod will raise up. When this takes place, the secondary ports are opened (that is when the rod is UP). You may want to spray some WD-40 or a similar lubricant on the dashpot mechanism, and work it up and down to loosen it up a bit. To wire them open, you can just be creative. I just cut a piece of wire, and looped it around the mechanism when the rod was UP (after you've blown into the line), and tied it off somewhere to keep the rod up. You'll see what I mean once you mess with it. You'll be able to figure something out. Many people say that doing this doesn't greatly affect your low end power, but I must disagree (at least for my car). When I did this, I did notice a huge improvement on my upper end power band, but my low end got much worse. Not to the extent that it wasn't driveable, just not near as powerful or torquey as it was with them closed. I've since UN-wired mine, and have been spraying lubricant on them in hopes to free them up and allow for proper utilization of the VDI system. I'm going to be buying a set of the Pineapple Racing port sleeves, and installing them sometime soon, and at that point I'll also remove the dashpots and they will undergo extensive cleaning. I really think that when working properly this VDI system will be great! Anyway, good luck and let me know if you need any clarification, or maybe a picture or two.

-Derek

Mark S

iTrader: (1)

I think the guy above is talking about the 6 P actuators. The VDI controller (I think) is sort of underneath the intake spider.

Could anyone verify this ( I only just bought my 89 --had an 87 before)

Samps

thanks for the reply but I was asking about the VDI. Your info is greatly appreciated and understood.

The VDI is a totaly different system from what i've read, but both work off the pressure from the air pump. And without the pump the system will not work.

NCsublime

Oh ok. You mentioned the port sleeves which is a part of the secondary port system. That's why I thought you were concerned about the ports. That's what everyone is referring to when "wiring open" the secondary ports anyway.


-Derek

Samps

So NC; you got any good info on the VDI?

turboren

The VDI valve sits in the intake below the surge tank. If you look from the driver's side, you'll see it in between the primary runners. It's got a vacuum diaphragm that actuates the valve via a rod, much like the six-ports. The diaphragm is actuated by one of the solenoids in front of the oil fill tube, and I believe it works off of vacuum, not backpressure. The solenoid is controlled by the ECM, and is energized when the engine speed exceeds 3500rpm (I think, may be 4000).

The purpose of the VDI valve is to control the length of the runners. At low rpm, the valve is closed, which makes the runners long, improving low-end torque. At high rpm's, the valve opens, allowing a shorter path to the engine for a ram effect.

All fuel-injected Mazda rotaries since 1986 use an intake designed to improve power and torque by using the "shuttle effect" or "dynamic effect." This is the process whereby the intake air is forced into one chamber due to closing of the intake port on the opposite chamber (wave reversion). This effect was what made the difference between the 84/85 GSL-SE's 135hp and the 86-88 NA's 146 hp (in fact, the name of the intake on the 86-88 NA cars is DEI for Dynamic Effect Intake). 89-91 cars use the dynamic effect, too, but they use the VDI (for Variable Dynamic effect Intake) valve to tune the effect for two seperate rpm ranges. This is why the series 5 engines feel much torquier (properly working models, of course) than their series 4 counterparts. In reality, peak torque only went up by 2 (138 to 140), but the average torque for a stock series 5 is much higher than a series 4, and low end torque is greatly improved, making an incredibly wide and flat (for a NA rotary, anyway) torque curve.

Hope this helps,

Ren

Mark S

iTrader: (1)

I had spoken to mazdatrix about removing the airpump and was told that both the VDI and the 6 ports are actuated off the air pump/acv --making it positive pressure and not vacum that actuates them.

Samps

Turboren with that kind of knowledge you better bump up that post count and share the goods

That was exactly what I needed. Is there a way to have a functional VDI without the air-pump? And is there a way to check it?

pp13bnos

iTrader: (1)

It was my understanding that the vdi opened up at around 5.5k. Atleast on my 90, there is a large difference when it hits that point. CJ

Samps

After researching these pinnapple racing 6th port sleeves, i think i am gonna keep the pump and use these new fancy sleeves. With brand new ones and everything cleaned out, things should work alot more smoothly. Is there an ATF trick to use on the intake track? How can I clean up the slots for the sleeves while there out?

mazdaspeed7

Samps, most of the people who have removed their air pumps on 89-91's wire their VDI, usually to the high rpm setting. The low rpm setting makes the car much more drivable, and with an impressive low end. With it set to high, your car will be faster, and much more rev happy.

I have mine set to high rpm setting, as does Bambam7, and we both have low 14 sec cars.

turboren

It could be 5500, but I'm pretty sure it's around 4000, maybe 4500 tops. My reference material hasn't gotten here yet. It makes sense when, you think about it, that the intake would shorten halfway through the rpm range.

As far as the VDI diaphragm being positive-pressure operated, I couldn't say. I don't have my 91 here with me, so I couldn't tell you for sure one way or the other. And I never did get a FSM for my 91... I'll have to trust someone else's judgment on that issue. I know that one of the reasons the series 5 NA's have one extra solenoid valve is because one of them actuates the VDI diaphragm. Whether perssure or vacuum operated, I really don't know for sure.

Samps, thanks for the props

Ren

turboren

BTW, it should be noted that Mazda accomplished this variable-length intake design nearly a decade before anyone else used it (on production cars, anyway).

Ren

NCsublime

Hell yeah.

SpeedRacer

The VDI actuates at 5700 rpms. On 89+NA's, the 6-ports AND VDI are actuated from air pressure provided by the airpump. The air is then directed into the ACV and released by the solenoids at the required RPM's. I also just wired open my VDI after removing the airpump. If you don't wire open your VDI your high-end will suck, although admittedly the low-end you lose is definently noticeable. Still, its definently worth wiring it open.
If your airpump is removed, you would have to electrically activate the VDI. You could get an RPM activated switch, and and a servo motor or something.

kliftin

Mazdaspeed7. Wouldnt it be better to take the vdi off entirely. Can it be done. I always had my vdi closed after the air pump removal and thats prob why I never noticed a diff in low end. I want to wire it open now. How did you do yours?

Hey mzdspeed7. You should glue those pinaple sleeves in your block. Or have you made some already.

Speedracer. Where can I get an rpm activated swich.

SpeedRacer

www.summitracing.com has the switch. You can wire your VDI open the same way as you can your 6-ports. Just remove the dashpot, and manually push up on the actuator arm and zip tie it that way. You can't remove the VDI, just the dashpot that activates it. the VDI effect is built into the manifold itself.

1.3liter_of_power

VDI manifold force's additional air into each combustion chamber by generating pressure waves in the intake tracts. The VDI solenoid valve has a white sticker on it and, is located on the drivers side right by the oil fill tube. The rods in the manifold that open the ports are operated by the air pump, the soleniod valve is operated by the ecu, it open's up the little door in the soleniod at 5500 rpm. There for letting in the air from the air pump, to open the VDI ports. Same thing with the 5/6th ports, it's soleniod is on the left side of the VDI soleniod valve, it has a brown sticker on the 5/6th port soleniod valve. Even with a full 3inch straight through exhaust, there is enough pressure from the air pump to open up the 5/6th ports and, VDI ports. All these people who wire open thier ports on 89-91 RX-7 should not, you lose to much low end torque, that makes your car slower. What I did was, I took the soleniod off and, went to the hardware store and bought a valve and these two cone shape pieces that vacuum lines will go over, make sure they will screw into both sides of the valve. Then, hook the vacuum hose's over the two cone shape pieces that you screwed on to each side of the valve. Next, you will need to adjust the valve so that it let's in air from the air pump to open up the ports at 4000 rpm and 5000rpm for the VDI ports.
Hope this helps

91na
intake,exhaust,S-AFC

1.3liter_of_power

I meant the the rising pressure in the lines between the air pump and the air control valve opens the soleniods not the ecu


91na
intake,exhaust,S-AFC:p

mazdaspeed7

You dont sound too familiar with the VDi system. Unlike the 6 ports, the VDI was a good idea, very well executed. The valve itself creates no turbulence or obstruction. If you removed it, the open chamber where the valve is would create a lot of turbulence, and would have an unpredictable effect on the powerband. To wire it open, you just open it, and wire it so the actuator doesnt move. I used safety wire.

I made something similar to the Pineapple sleeves, but mine dont use the sleeves at all. https://www.rx7club.com/vforums/show...threadid=37636 I posted a while ago when I did it. I must say, I was very impressed. Low end was even better now(my VDI is wired to high rpm) than it was before with the VDi wired to low rpm. It helped at the top too, just not as noticable. I would recommend everyone to get the Pineapple sleeves, or make something similar.

Just an observation I made which I see quite a lot here. Someone asks a question and people go off on so many things that do nothing to answer the question. Samps wanted to know what he should do with the VDI if he removed the air pump. He did not ask for a detailed description of what it is, how it works, and what it does.

kliftin

NCsublime

"Just an observation I made which I see quite a lot here. Someone asks a question and people go off on so many things that do nothing to answer the question. Samps wanted to know what he should do with the VDI if he removed the air pump. He did not ask for a detailed description of what it is, how it works, and what it does."


So, what harm is done if Samps figures out his problem (or maybe even not) and SOMEONE ELSE learns something? It isn't a thread designed to answer only 1 question and be done. It's meant to explore the matter.

Thanks for the info guys.

-Derek

Samps

Regardless of what the original question asked, this thread now contains some really good info, and anyone who reads it will probably learn something; that's all that matters. NC's reply may not have directly answered my question but it was related to the subject and posted with good intensions. Sometimes people do post random stuff in a thread that does not relate to the topic at all i.e. a thread about exhausts and someone tries to sell some wheels in it. Anyway you look at it, this thread probably helped alot of people, and I thank everyone for trying to help me out.

mazdaspeed7

I never said it does any harm, and I agree, there is lots of good info on the VDI system here. I was just mentioning that nearly all of the posts here have gone off on things that dont have much to do with what the original poster wanted to know. I see it on the forum all the time, not just this thread. It was justa good example.