Okay folks, whats up? I am a self-admitted NOOB.... I would just like to say that I started out being the not-so-proud owner of a 85' Z31 (300zx) <--- a piston motor
(for those stuck on the rotory) I have now moved on, to the 91' FC3S, N/A 5 speed wonder-mobile. It has 80,000 miles on it, I am going to replace the plugs, and forgive me, and please don't flame, but I still am kinda stuck on the whole concept of exactly how the 5th and 6th ports are supposed to work correctly... is there any particular keyword I need to use in the search to find the optimal RPM range for them baddies to open, and also for proper repair.... Thanx for putting the site up and I again thank you for not causing large amounts of pain an suffering in my pantalones.... -Comet

 

The fith and sixth ports on your car are controlled by the ECU.. at 4.5K prm, the ecu opens a solenoid that allows pressure from the Air Pump to go to the actuators and open the ports inside the housings.

If you have a cone filter on your intake, you can hear the six ports open if you drive close to a gaurd rail with the passenger window open and mash the gas. at about 4.5K you should hear what sounds like a chainsaw slowly reving up begin to come from your hood. this the extra air being drawn in through the intake and reverberating through the snorkle and filter.

I bypassed my ECU and used a summit racing switch to open the six ports at 5.25K on my gtu and it seemed to like that! But generally, you really shouldn't need to mess with it.

But don't make the same mistake a lot of noobs with s5 (89-91) N/A rx's do and take the air pump off, you need it to open the six ports..

 

Your series 5 intake also has a VDI (variable dynamic intake) that kicks in at ~5800.
It's controlled by the same pressure source as the Aux ports.
BTW: The renesis engine in the RX-8 uses an advanced version of the same features.

 

Try 3800 on a aux port... not 4500...

The aux (or 5th/6th) ports open at 3800 on a stock engine. The same time the 2ndary injectors kick in.

And why you have yours opening so high is beyond me... do you have major porting or something??? With stock porting and mostly stock intake you are just throwing away torque by opening them so high.... and 5200 that is where the VDI opens.... opening the aux ports at that, you are probably way low on low end torque and HP>

 

To paraphrase:

They work like the secondary venturis on a carbed motor.

 

Or VTEC! lol

 

lol, V-TECH.... Very Technical Ever-Ready Cup Holders....

Thanks for the input, the car at this point is in full stock form, I do have a cone filter on the way, unfortunatly I live in montana, so performance parts for any car, especially a rotory are hard to come by, but I truly appreciate all the input!! Thanx!