I read recently in my little mazda shop manual that 6 port actuation is achieved by AIR pressure from the air pump. NOT back pressure f/ the exhaust like I was told for so many years. Which makes sooo much more sense. Mazdatrix Racing Beat and other sources have told me that it was operated by exhaust back pressure. Anyhow if you guys have any further imput I'd like to hear it before I install my Racing Beat Exhaust and rip out the air pump like they tell me to.

 

S4 and S5's 6 port actuation are different. The s4's use back pressure to trigger the opening while the s5 uses an electrical system.

 

Series 4 is done on back pressure from the exhaust.
Series 5 is done by means of the air pump and other electrical solenoids.

 

Yep, as the above answers say...

84-88 non turbos uses exhaust back pressure to open the aux ports

89-91 and 04-05 use air pump pressure through switching soleniods to open the actuators for the aux ports and VDI.

 

what about 88 turbos? from what ive heard it doesnt matter (in relation to the ports) if you remove the air pump on a turbo.

 

The air pump is needed for emissions on turbo cars, but there are no aux ports or anything like that on a Turbo motor.

 

yeah i just passed emissions so **** em until next time, ill be pullin all that **** out this next week. thanks!

 

I have a '90 GXL. Being an S5 and not using backpressure to open the 5th and 6th ports, removing the cats would have no affect on them or the VDI as long as I left the air pump alone. Is this correct?

 

Correct - until the air pump mount bracket breaks.

 

^ Can you give me some more info about this?
I would like to go striaght pipe to a cat back, but would also like to keep my 5th and 6th ports, and VDI operational.

 

So, removing the airpump on a series5 is a stupid thing to do?

 

in Short..... YES!!

 

Thanks guys for your imput I reallly appreciate it. Now I'm gonna chicken wire my 5th & 6th permanantlt open! I'll let you know how it acts. I use the K.I.S.S. method.

 

You know that has been dyno proven to loose HP and torque at below 3500 RPM.

Nothing like making a car with no torque when starting off at at light even worse

 

Yes - keep the air pump on a S5 until the bracket breaks, then for $30 you can rig an electric pump.

 

Has anybody tried wiring them "half" open? Mayeb for normal street driving where low end torque is nice, but with a loss of possible power up high.

If somebody had aux ports that were not operating and are not interested in FIXING THE PROBLEM this may be a nice compromise on low vs high in power..

What do you think Icemark? Has this ever been tested? Or is there soem reason this would not be good? (Maybe the air flow would be really bad etc)

 

Yes, half open would NOT be good at all....

Personally I just took my sleeves out altogether. Didn't look back, made more topend for sure (no dyno sheet unfortunatly..)

 

Yes, leave the airpump alone and you'll be peachy. As far as straight pipe to cat back, it's definitely louder than stock and drones a bit, but as long as you aren't running a header and straight pipe you should be ok. I did that for about two and a half years before getting the header and pre-silencer. The increase in power from stock to straight-pipe to header/presilencer was about the same by butt dyno. As far as wiring the ports open or removing the sleeves.... horrible idea. I ran my car without sleeves for a while, and after cleaning up the actuators and putting stock sleeves in, I noticed a huge difference in drivability and launchability.

 

Why would the bracket break?
Would straight pipes from the stock manifold to an apexi N1 dual be unbearably loud? Anyone have this set up on a NA car. Would like some comments. Thanks.

 

I'm not directing this at you, just the hypothetical people in your example.

If you're not interested in fixing problems and improving the condition of your vehicle, sell your 13-18 year old sports car and buy a Honda where nothing breaks. FCs are not young cars and owners that are interested in "ghetto-rigging" and half assing need not apply.

 

I had the manifold to straight pipe to HKS Sport(dual 50mm) and it was louder than stock(obviously) but not excrutiatingly loud. I'm not sure how the Apexi volume compares to the HKS though, but I think HKS is supposed to be more on the quiet side. Like I said, I ran it for about 2.5 years and then got something louder

 

I totally agree. I enjoy working on my 18 year old car and making it work correctly. I don't pretend to know better than the engineers that designed the car.

As far as removing the the sleeves I would never do that. The idea that I would trade some of my precious low end power for high end power I don't normally use dosesn't seem like a good idea.

 

Maybe my **** just isn't sensitive enough, but when I took out my sleeves I didn't notice any appreciable difference in 'low-down' power... at all.. Definatly an improvement in the higher RPM regions though..

Maybe it's just me...

 

Why would removing the cats cause the air pump bracket to break?

 

The NA air pump bracket will break if you are not careful when adjusting belt tension.
Mine was broken by my friendly neighborhood AC shop.
It's just a small aluminum casting.