Marco

I bought a straight pipe and removed the cats from my 1988 se. I would like electronically activated sixth-ports, (and at adjustable rpm's from inside the car would be really great). But I haven't got the place, time and money to do that now so I've wired the ports open. Some say this wil make the car loose a lot of low-end torque. Others say that the low-end torque loss isn't that much at all and the hp-gain in the high-end is much more preferrable. So I'm gonna do some driving with and without the wiring soon to find out for myself. But I was thinking, what would happen if I wire just one of the ports open. Would this give some more low-end power and a little less loss of high-end power. Or would the car just run like **** because one of the rotors get to much fuel and the other rotor not enough fuel. I wonder. Do yo think it is bad for the engine to try?

Marco.

Samps

It should not be bad for the motor because the ECU does not know wherther the ports are working or not so it sends the same amount of fuel regardless. You will loose about 10-15 rwhp and torque under 4k rpm with the ports wired open and gain NO hp at any rpm. There is no way to gain unless you remove the sleeves all together and smooth out the openings, and even then you will still loose a considerable amount of low end. Leaving them closed is even worse yet. If you can't have them working then keep them open. But having them work is by far the best solution.

Marco

I do not agree. First at about 4000rpm the secondairy injectors will kick in. When the sixth-port is not open by then the mixture is too rich, The 02-sensor detect this and the ECU compensates. Below 4000rpm the secondairies are not working. When the ports are open this means that the mixture is too lean and again the o2-sensor signals this to the ECU which compensates by means of more fuel.

At least, this it what I think that happens, maybe I'm wrong.

Marco.

rotarygod

iTrader: (1)

If you just wire one open you are not going to get the best of both worlds. In fact it will probably hurt your performance and give the the worst of both worlds. One rotor breathes good up to about 4K rpm or so and the other breathes best above that point. You'll probably find that the engine makes less power everywhere if you do this.

For a daily driver just find a way to keep them working. If this isn't possible then at least wire them open. You will lose a little lowend like everyone says but with no power gain. Why would it? The only way to gain top end power is to remove the actuator rods from the airstream and radius the sleeves.

Samps

This might be true, but I do not have that much faith in the O2 sensor. Maybe someone with a little stock ECU fuel managment knowledge can chime in and settle this.

After it is all said and done; having them working is the best way.

SureShot

Samps has it right.

Here is a simple test.
Do a low end pull using 3rd gear & time how long it takes to accelerate from 1500RM to 3500RPM.
Then wire the ports open and compare.

KiyoKix

I'm a big fan of the 5&6th ports, so I vote to keep them on the island . The loss in TQ is just not worth it, yea you gain power in the mid/high side of things, but that'll still take away from the acceleration of the car because you'll lose TQ and it'll be similar to the Honda motors, they have next to no TQ on the bottom end and are basically like 2 seperate engines (actually more like the Celica GT-S engine...damn I hate that thing), but pull like mad on top. That's just not worth it, the car will be faster/quicker overall if you just leave them in there.

KiyoKix

By the way...nice looking car .

Roy James

fuel maps.. O2 is only used at cruise.

vaughnc

If you have straight pipes, I've heard a pre-silencer between your downpipe/header & straight pipe will provide enought backpressure for these ports to work.

Hope this helps, and kills some of the ear bleading engine noise.

NZConvertible

No, the operation of the secondary injectors and opening of the auxillary ports are completely unrelated. When the secondary injectors are brought on line, all four injectors fire at half the pulsewidth the primaries were previously firing at. This means there's is no change in the amount of fuel being injected at the changeover point. The mixtures will be whatever they were before. The O2 sensor is only used at idle at under light loads (cruising). For anything more than mild acceleration, the ECU's fuel maps are used. Airflow is measured by the AFM and fuel requirements calculated from that.Same as above. Fuel is calculated based on measured airflow, no matter whether the ports are open.

BTW everyone, they're called not sixth-ports or 5th/6th ports or 5&6 ports or whatever else they get called. None of those make any sense. They're called auxiallary ports, and the complete system is called the Six Port Induction system, or 6PI, as per the Mazda FSM's.

dumarjo

I have wired my 5 and 6 port I confirm that i loose som hp below th 4000rpm. cannot sai how much but i loose somes.

my 2 cents