WanKeL FD RX-7

iTrader: (7)

I'm putting a GSL-SE engine in my 83 GS. I have all the parts, including the stock SE's lower manifold. But there's no actuators. So i have the choice of running 6 port open like a 4 port engine, or put sleeves and actuators to run it like the stock SE's does. But, i heard the actuators connects to the exhaust and uses the backpressure to open the sleeves at 4000rpm. But, i have the RB complete exhaust on my car. How can i set it to work ? What are the problems running it 6 ports open?

Max

MosesX605

You could modify the headers to run an actuator tube up to the ports, like RB does, or you could just run the ports open. Many FC owners run with their ports open, which in theory hurts the low-end some, but eliminates the complexity of the actuators and the chance of failure. I don't have any experience with 6 ports, so I can't speak to the possible low-end loss, but if it were me, I'd try it without the actuators first.

WanKeL FD RX-7

iTrader: (7)

ok, thanks

purple82

You also have a bit better flow into the secondaries with the sleeves removed since there aren't any sleeve or actuator parts in the airstream. I've been running my street port without secondaries. It may have lost some torque in the low range compared to stock but it's still more than the 12a had so you probably won't notice.

WanKeL FD RX-7

iTrader: (7)

yeah that's what i thought

smnc

There is also a way to hook the actuators up to the airpump, but I don't remeber the specifics.

riffraff

the actuators on a s5 n/a motor are air pump activated, rather than back pressure. you could retrofit those i suppose. otherwise, you would probably want to hook the air pump back up to the acv, and then find a way to go from the acv to the actuators.

Hyper4mance2k

iTrader: (40)

open mine are open wih a big weber and i have plenty of bottomend.

MyRxBad

Which RB Exhaust do you have? I hope you have a 13b header or exhaust manifold.

In order to make the 6ports work, you'll have to do it one of the ways the guys above me said.

LongDuck

When the '6' ports are setup correctly and working properly, they work very well. The 84SE was the first model year to offer this on the 13B engine with EFI and the 'dynamic chamber effect' was supposed to be augmented by the proper use of the '6' ports - which was the 'variable valve timing' of it's day for the rotary engine.

The SE had a very flat torque curve because of the '6' port technology, and this was something that prior models of the 12a RX7 were needing through buyer feedback. When Mazda introduced this system, it was a workaround to build greater low end torque by keeping the air stack velocity at a high speed, which assists with getting more air/fuel into the chambers at low engine RPM. At higher RPM's the engine needs greater air/fuel mix to rev, and the '6' ports allowed for this greater volume without hurting low end performance. In effect, the porting arrangement allowed for good torque to be build below 3800 rpm, then at 3800, the '6' ports would open and remain open to redline. Once you back off the throttle, the '6' ports immediately close, increasing air stack velocity for the primary and secondary ports.

This arrangement made for a very flat curve which is what gives the SE's the better acceleration performance than the previous 12a cars. The acceleration from dead stop requires low end torque to overcome mass, so bringing the torque curve down is a necessity to get good acceleration.

I run the standard '6' port setup on a RB header designed for the EFI setup. Once cleaned thoroughly, the ports open correctly at 3800 rpm, and you can feel the engine change to the higher velocity band and feel the second 'kick' of acceleration as the engine opens up. For this alone, in my mind, it's worth doing it the way the Mazda engineers designed. For performance that you can feel, I recommend doing it the way it came from the factory.

For proper '6' port actuation, you need to be sure that your lower manifold is clean and smooth for the rod actuators, and also that you don't have any vacuum or pressure leaks in the lower manifold or actuators that would prevent them from opening. Any leak will cause the 4-6psi required to open the '6' ports to be lost, effectively killing the benefit of '6' port induction.

When they're running correctly, this is one of the features of the 13b SE's that make them stand out, for both design engineering and for performance on the street.

BigJim

how can i tell if my actautors are working, currently they donot because my backpressure pickup was broke when i got teh car and havnt had money to replace, but when i do, wat should i look for to see if they are working

LongDuck

Put some grease on the actuator shafts where they enter the body of the actuators and then go for a spirited drive. If your '6' ports are working correctly, on inspection, you'll notice that the grease has been moved 'up' the shaft, indicating that the shafts are moving, and the actuators are working.

Keep in mind that you need to develop 4-6psi of exhaust backpressure to get this to work, so you'll need to accelerate hard beyond 3800 rpm to get the actuators to open up fully. They will gradually open at 3800 rpm or so, and be fully open at 4000 rpm or so.

You'll also want to see that the grease movement is even on both actuators to be sure that both '6' ports are opening the same amount for maximum performance. HTH,

BigJim

where are these so called actuator shafts.

O 16581 72452 5

They're on the sides of your intake manifold right above your exhaust manifold. They resemble upside-down mushrooms. I wired mine open and honestly didn't notice a dramatic loss in low end power.

nlc1179

just run them open

BigJim

wich way do the little plunger things move(stem of mushroom)? do they go into the mushroom, or move out of the mushroom?

O 16581 72452 5

Down - Ports open. Up - Ports closed. Remove your actuators with a socket and wires the ports open with zip-ties. It should be pretty straight forward what to do once the actuators are removed.