RX7freak08

Now on a 6 port engine does the 6 ports stay open when you shift. Say you go past 3000 and your ports come on until like 6000 and you shift do they turn back off or do they stay on.

Aaron Cake

iTrader: (1)

They probably start to close again as the engine load is very low when you let out the clutch, but they will snap open quickly as soon as load is applied to the engine.

RX7freak08

So say if I wanted to do the electric 6 ports right. I didn't want to spend the money on a rpm switch right away and I just added a switch to the dash for it. So i would have to turn it on every single time It would get up to 3000 rpms.

clokker

iTrader: (2)

Um, yeah.

If you want to do the aux port conversion "right" that pretty much means you have to spend the money on the RPM switch right away...no way you could be manually activating the ports (especially with a dash mounted switch), shifting, steering and watching the road all at the same time.

RX7freak08

oh ok thanks

RX7Tuner.

The 5th and 6th need to be opening properly if this is an S5. If you choose to manually open the ports you will have to do it everytime you go above 3,800. If you don't, your car will go dangerously lean. When your car hits around 3,800 your primary injectors drop to roughly half duty cycle because your secondary injectors are kicking in to make for a smooth transition. The problem is the secondary injectors are sending fuel through the 5th and 6th ports, and if you leave them closed then your car's fuel supply was just cut in half, making for a lean AFR that is not good for your engine.
Overall, it's not a good setup. You want the rpm's controlling your fuel delivery, not your finger.

Good Luck,

Brian

Mechanic

sorry for the noobness, i understand that the s5 5 and 6 port doesnt run off exhaust backpressure, so does that mean i can remove the air tube? i am keeping air pump operation... would it affect the 5/6pt operation?

RX7freak08

ummm well what if I left the ports opent the whole time

Latin270

Mine are left open all the time.....but then again I'm running a carbed s5.

Roen

iTrader: (2)

yes, on an S5 you can remove the split air tube. That's what I did.

Aaron Cake

iTrader: (1)

That's insane.

Why not just leave the airpump installed?

And no, you can't just wire them open. We've covered this many times before. Massive loss of low end torque, no gain in HP up top.

RX7freak08

Really I'm not going to put the air pump on it either i'm going to connect the piping to the exhaust or i'm going to save up for a rpm switch. There is no way that i'm going to put that **** air pump on my performance car. Aaron you read my Street ported engine for the second time thread you know what i'm going to be doing.

RX7Tuner.

For the ports to open and close properly on an S5 you need to have your air pump pressurizing a 5/32 hose to the correct solenoid (on the emissions rack) and then running another hose to the port actuators. You could wire them open (I am currently) but you have a major loss of low end and you'll end up driving around feeling like a wiener because your ports are wired open.

There is a writeup on Rotary Resurections website about using an electric air pump to open and close them but it's just not a reliable setup for long term use. Bike pumps are not meant to be running all the time (if you race it would be running non stop) in 140 degree temps. And if it stops working and you don't know it stopped, well you're back to running lean.

Brian

jd to rescue

iTrader: (3)

Sorry to revive a couple days-old thread, but I have a related question. My nephew has an s4 and we were trying to diagnose a problem we believe exists with the 5/6 ports. Applying air pressure would activate the actuators and move the valves freely, however, with no load on the engine, we could not get the actuators to open for us above 3000 rpms. I have a lift so I raised the car off the ground and engaged first gear but still got no response from the actuators at higher rpms. My first question is whether merely engaging first gear is enough load to build adequate back pressure for the function of the 5/6 ports? If they should open, the next question is related to modifications to the exhaust. He appears to have had an exhaust guy revamp his header to resolve an exhaust leak. If the presilencer is altered is that possibly preventing enough back pressue to drive the actuators? He has RB cats and mufflers.

Roen

iTrader: (2)

that's a common problem with the S4 NA's.

If you go to a freer-flowing exhaust, backpressure decreases and the 5th/6th ports open at a later time. The design was improved on the S5, using airpump activation only.

You do have a couple of options though. You can use an rpm switch or rig up a modified airpump activation. I think some owners have done it before.