Alternate S4 5/6 Port Activation
 

I am wondering if anybody has any experience in an alternate way to open the 5/6 ports on an S4? I have read about using an RPM switch to activate an air pump to open the ports, but what about using an RPM switch to activate electric solenoids on the manifold?

I have an 86 S4 motor in a B2200, not sure if I have enough room for the stock actuators (probably do but will be tight), but I have a pacesetter header, and 2 Magnaflow mufflers, so I don't have a port for the actuators, and probably not enough back pressure to work them anyways.

Another option I thought of is using engine vacuum. I will need to find some vacuum pots with the right amount of movement. These will work opposite from the stock actuators, where intake vacuum will pull the ports closed, and as vacuum decreases, the ports open. When the engine is turned off, the 5/6 ports will open.

The problem with electric actuation is that you would need something strong enough. Maybe you could rig a Ford IMRC motor to work. The one on the 3.8 split port V6 has a double pull rod setup that you might be able to rig up to work if you could mount the motor where the ACV would go.

I've seen the seat pump method but in my opinion it didn't feel very good to drive. Like there was "actuator lag" if that makes any sense. I've always just removed the actuators and sleeves and drove it like that.

I originally had them open, and it was laggy at lower rpm's, but fun at upper RPM's, struggled to maintain 60MPH in 5th too, but I have the truck's rear gearing, which is 3.9:1, so I am doing 2200RPM at 60MPH, and the B2200 is slightly less aerodynamic and probably heavier than the RX7 lol. I like how it feels down low in the RPM's with the ports closed, and I plan to use the truck as a truck still, so I like the torque. I am planning on swaping 5th gear from the B2200 into the RX7 transmission, instead of 0.69, its 0.89.

put a turbo on it and route some boost to the pots.. they will swing open just under 2 psi

Euro 6port setup is just run off vac with a solenoid(which a rpm switch could control). They are more compact because of thermal reactors instead of cats there was little room for the diaphragms on the outside of the manifold.


Thats a video Higgi made on how they work. I have one for athe hopeful 6port turbo build.

You could try to retrofit the motors used on the Renesis engine.

Are you running true dual exhausts all the way out? If not...
Why not add one of these Presilencer for 86-88 RX-7 Non-turbo - Man Trans - Racing Beat after the pacesetter header, but before the magnaflow mufflers.

Or if you want to rig up an RPM actuator for the aux ports, consider swapping a S5 NA VDI intake on top.

https://www.rx7club.com/attachments/...3-13-26-14.jpg

Works/easy.

Keep in mind the 6 ports take TWO variables to actuate: engine load AND rpm. Thats why the stock system worked so well with exhaust backpressure. You don't want the ports open at part or closed throttle, mid/high rpm.

I use a pressurized CO2 system with eBay 3-way solenoids, controlled by a Megasquirt MS3x, actuated with fuel load above 60 (%) and RPM above 3800 with a 200rpm hysteresis.

If you dont have a programmable computer, your best bet will to be to tap the front header right at the bend and add a tube which tees to the aux pots. A longer, coiled tube will help with cooling if you start melting hoses.

Ala RacingBeat:
http://www.racingbeat.com/images/items/16128.2.jpg

all this time and nobody ever used a mechanical linkage to open them with the throttle. like one using bicycle cables.

something i suggested years ago.. then i went turbo

You'd want them to be RPM based not throttle based. Otherwise there'd be no difference compared to running them removed.

No necessarily. If you had the throttle wide open then they would be open, but if you were running say 1/2 throttle they could be closed.

And if you were running wide open at 2500 they'd be open, too. Which completely defeats the purpose.

not if your craft is wise.

what i mean is, i would have the primary ports throttle max out at 3/4 throttle, the rest of the travel opens and closes the aux ports without changing the primary ports opening angle until under 3/4. this would be done with a spring and a slotted piece of metal. :lol:

it would give the option to open them up dependent on the driver. just light mechanical secondarys on the fb's nikki.

too complicated, and it would be slower than stock...

the 5th and 6th ports are like changing the cam timing, more than they are like opening the secondaries on a carb, which is why they need to be switched with RPM, and not throttle position. :)

All of these suggestions have been tried years ago, including being actuated by a bicycle brake cable. They were always setup to activate by rpm which was preferable opening by exhaust pressure since exhaust pressure could potentially open them too early. A 3500-4000 rpm opening based solely on rpm alone is the perfect way to go.

I have had a thought, I work at a powersports dealership in the service department, and a lot of motorcycles have valves in the exhaust pipe that open up to give a less restrictive exhaust (same thing as the Corvette has been doing for awhile), and we also sell snowmobiles, that use a variable size exhaust port to keep torque down low, and opens at 6800RPM. A 2 stroke sled motor revs fast like a rotary, and that motor must be quick at opening, both the bike and sled actuator motors look similar, and are cable operated. The sled motors, have 2 cable outlets, one for each cylinder, I might try to get my hands on one and see if I can get it to work with an RPM switch.

Only problem, is that those motors are a couple hundred dollars, which is way overpriced for what they are lol, but I will look into it, wont be anytime soon though.

http://www.ebay.com/itm/OEM-EXHAUST-VALVE-SERVO-MOTOR-w-cables-06-14-YZF-R6-R6R-EXUP-ACTUATOR-/181546994415?pt=Motorcycles_Parts_Accessories&hash=item2a450b4aef&vxp=mtr
at between $60-75 i'm gonna pick one up, if nothing else i can use it on my "sometimes-full pp engine"