Hello everyone,
I am currently in a conversation with the owner of JAFA Engineering concerning a set of fully electric Aux port actuators. I searched the 1st gen and 2nd gen forums to see if anyone has tried these. Other than a few intake manifolds/adapters from this company, it appears that no one has. With this said, and assuming that no one has a set of these, I will try and set and see how they work. I will report back to you at some point in the future. From what I understand, the actuator positions are mapped to engine RPM and give a nice, gradual opening from 3,800 to 6K. They are fully open at 6K. They also are mapped to close in the same way by RPM. The guy did say that he had problems with the GSL-SE, but a tach signal filter rectifies the situation. Since I'm running a Haltech, he said that there shouldn't be any issues. I welcome your thoughts or comments. But please don't ask me, "Why do you want to try these?"

 

You probably noticed in your research that the 84/85 SE used exhaust system pressure tapped from the Main Catalytic Converter and routed theough a one-way cone valve to the Lower Intake Manifold and the Variable Port Valve Actuators. These use 4-6psi of volume driven air piped off of the exhaust to effect function, and as such they operate smoothly based on the intake volume, fuel burned, and back pressure to open and close the ports smoothly, and only when needed. Contrast this to the 2ndGen cars whereby Mazda chose to operate the 6-ports via Air Pump pressure and a vent solenoid valve, controlled by the ECU and using vacuum at the intake manifold instead of exhaust. The Air Pump merely provided the pressure to operate the Actuators, as the switching was done by electrical signal.

What you're working toward is closer to the stock 2ndGen system and I'd be curious if these are variable servo controllers or simple electromagnetic relays which open and close the cylindrical ports. For obvious performance reasons, you'd want port position to be variable and matched to something related to power output or intake charge volume or you'd abruptly change the Primary Intake Port velocity, which would hurt performance across the powerband. I think that would be my question of the designer and listen closely to how he's solved that particular problem before veering off of a design which Mazda perfected over time, and which works perfectly to deliver a smooth torque curve across the useful powerband when it's working correctly.

Let us know what you find out. I'd be curious myself.

 

LongDuck, since we are rarely cruising above 4k without load wouldn't it be safe enough to make some assumptions here that if you are above 4k you are probably also in load? Using this system the ports are gradually opened based upon rpm (controlled via MG90s servos) with full open at 6k and full closed at 3.7k (source: eBay). At 3.7K in fifth gear you are traveling at around 80mph and 60mph in 4th. Surely, one isn't cruising on the street at 6k in 4th or 5th gear (100-125 MPH)

I understand what you are saying about this needing to consider load instead of solely RPM. I had similar thoughts while I was working on my own design and came across this solution. But figured this was good enough for daily driving. I'd like more discussion about this. Maybe I'll pickup on my work or try collaborating with JAFA to add a vacuum sensor into the mix.

Ultimately, I'll likely either buy the RB presilencer or this. I really wish that racing beat would have offered https://www.racingbeat.com/RX7-1986-...ers/16128.html with a single outlet.

 

I think that best of both worlds would be to have this sort of a set up (like the JAFA set up) but have the mapping according to both RMP and TPS. As you both have alluded to, you can have high rpm's with very little load and vice versa. Wouldn't including the TPS in the mix solve this and give the best outcome?

 

In my case, I don't have a TPS as I'd still have a carb so another signal (such as vacuum) would benefit me. You may be asking yourself how? I'm working on an adapter to mate an IDA to a FC NA LIM. Just using what I have currently I'll likely go EFI later.

 

Sounds like a fun project.

 

Thanks. Keep us updated if you end up getting the accuators!

 

If you don't think cruising with no load at 4k is normal, you must be coming from FC-land 1st gens had smaller tires and shorter 5th gears than FC, even the GSL-SE.

4k is about 75-80 depending on tire size.

I've always removed the sleeves and the rods, because the rods and actuator sleeves represented a hefty flow choke at higher speeds, and a 13B in a 1st-gen is in no need of even more low end torque... Also the actuators were always broken!

 

In my experience, the Port Actuators are pretty robust, but the gaskets that seal them fall apart quickly, allowing the limited air pressure to escape and then the Actuators (*both of them) won't work. This is because Mazda designed the back pressure tube to go to the rear Actuator first, through 2 tiny holes just below the mount bolts, and then through a separate tube under the Lower Intake Manifold to the front Port Actuator. In this way, any problems with sealing either of the Port Actuators using their weird little gaskets lost enough pressure for them to operate at all.

You can't blow enough volume and pressure through your mouth to get them to move, and they DO NOT move when free-revving the engine with your head in the bay looking for them to work, because there's no load and not enough fuel being injected and burned. The ONLY test is to either hook up a pressure line with zero loss on the Port Actuator feed side and watch it while accelerating in 1st or 2nd gear on the road or the shade tree mechanic trick of using a dab of grease on the Actuator rod shaft and then driving it like you stole it. When you get back to the shade tree, open the hood and look to see if the grease has been moved along the Actuator rod, indicating that the rods are moving and rotating the sleeves.

 

when I had a 6-port I was able to get them fully open with a bicycle pump. For some reason they never worked with the engine, and I was using the Mazdatrix modified header.

 

My "butt-gauge" can usually tell when my auxiliary ports open however, I have also done the grease on the actuator rod test both under-load and with a hand pump like j_tso has done to check their operation. I can also actuate them manually, and I always try to hear the rev buzzer in a couple of gears whenever I take her out for a spin. And with the weather this coming week I will have that opportunity.
:-)

 

The pressure pickup needs to be further down the line to generate enough back pressure to correctly operate the 6-ports. I've run the Racing Beat Presilencer designed for the SE for over 20 years now, and it has operated the 6-ports correctly. They start to open at WOT at 3,800rpm and are fully open at 5,000rpm and remain open until you let up, at which point the rotary valve sleeves rotate closed. This can be felt in acceleration when they first open. Note that in the RB design, right at the front of the Presilencer you can see a funnel-shaped tube. This funnel helps to capture the high speed exhaust gas and build pressure from BOTH rotor exhaust right after the collector. This is the best place to draw the pressure signal for the 6-ports to open;


That tube makes a smooth bend to exit the Presilencer then a U-turn to point it back up to the one-way valve inline to the Port Actuators. Obviously the gasket here makes a difference, too - as pressure drop along the way will cause the Port Actuators to never see enough gas pressure or volume to open properly.

I hope the discussion is still valuable to the OP, and will help him gain understanding of how the Mazda designed system works so that he can find a way to mimic his with electronic controls through a servo mechanism. The reason why Mazda didn't use a mechanical system to operate these rotary sleeves is that it wouldn't operate correctly based on engine load. A mechanical system would likely be more reliable, simpler, and cheaper - but wouldn't allow the variable operation of these ports without sacrificing performance along the way.

Again I'll point out that all 2nd Gen Rx7s (*except TurboII cars) used air pressure off of the Emissions Air Pump to rotate the sleeve valves, so Mazda definitely saw fit to continue their use for NA engines. The TurboII cars reverted to 4 conventional ports for intake, because the turbo flowed better without restrictions and variations of air velocity like you'd get on a NA engine intake.

 

Only the S5s used the air pump for the aux ports. My S4 used exhaust backpressure.

 

Update: The aux port actuators solenoids didn't work out. They were high quality components, but for some reason, they just didn't work with my aux ports. The issue was that at rest, the solenoids would already have the ports opened up about 1/4 of the way. Also, at full travel of the actuator, the aux ports were only opened up about 3/4 of the way. So this issue was that the travel distance of the actuators did not match the resting and travel distance of the aux ports. I am imagine that it didn't work b/c I have the S3 aux ports. I sent the parts back for a full refund.

 

I wonder if that could be resolved with a firmware update?

 

Not sure

 

I have had electronic solenoids controlling the aux ports on my 13b for a couple of years now. They open instantly and fully at 3800rpm. The powerband is linear all the way through and you wouldnt even notice they opened. Any lower and you can feel the power loss. Any higher and it feels like a turbo kicking in.

 

i can easily blow through the vacuum hoses to get each aux port fully open. Everyone should be able to do this whether it's S3, S4, or S5 aux ports. If you can't blow into a vacuum hose to get the aux port to fully open, then you have an issue.

And as Peejay pointed out, the S4's use exhaust back pressure to open aux ports just like the S3 13B.

 

Jackson sent me another pair (prototype) to try, as the first ones didn't allow the aux ports to fully rest or fully open. I didn't get to install them yet. But when I do, I will let you know how they work.