Rx7TyreBurna

iTrader: (1)

So.... I was thinking. Is there any advantage to the aux ports being able to be opened partially?

Like.... opening based on RPM and load, a variable amount? I know that the aux port itself won't change the 'timing' of the port. But, could opening it partially help with air velocity?

I am still relatively new to tuning cars and 'load'....

Working on a system to open the ports a variable amount, controlled by a megasquirt. But, was wondering.... for torque curve, is there an advantage?

jjwalker

The short answer is "nope".

Rx7TyreBurna

iTrader: (1)

Thanks!

Oh well. Almost done with the mechanical system in solidworks. haha. Good learning experience.

Setting up some ports for flow testing anyways.

w0ppe

Solidworks is an excellent tool for any mechanist to design any product; especially for movement things.

What's your goal for this anyway? I'm sort of curious on what you're up to actually.

j9fd3s

iTrader: (3)

usually there is a small dip in a dyno curve when the port opens, as the 6 ports are opening a little too late or a little too early, both of which will cause a small drop in hp, but we're talking like 1-2hp at most. you might try changing the speed at which the port opens, to get eh air moving before the port is really open. also you might vary the opening rpm with load, at part load they can stay closed longer, Mazda used the AFM, the training manual has the graph, but under a certain airflow, the ports stay closed

basically its turd polishing. the system works well from exhaust back pressure, and to get it to work as well with a computer would take 10x the time, and cost.

if you want more power, you need more airflow

Rx7TyreBurna

iTrader: (1)

Right now, just playing with things. Flow on the ports, etc.

Eventually, I'd like to turbo the car, and keep the ports functional, but not use air pressure to open them.

I am going to be using a servo or something with feedback to actuate them using my megasquirt. I'm fine with open/close, but was curious about the possibility of half open, or something like that, tied to engine load.

I'll post pictures this weekend sometime about the working assembly to actuate the ports mechanically. Very simple design, might have to work some bugs out.

My goal with the car is not peak HP, but good area under the toque curve. So, if I go turbo, it's going to shoot for best overall power, not peak.

zak rabbit

Late to the show here, I know, but I have noticed the Renesis auxiliary ports are shaped such that they function much more like a "throttle" as opposed to an on/off switch.

Rx7TyreBurna

iTrader: (1)

Thanks Zak!

pfsantos

iTrader: (1)

True on the Renesis part, but calling the FC 6PI system an on/off switch is a bit much, lol. Its actuation and use of rotary valves is quite good.

Like J9fd3s said, the system is somewhat gradual, if not very refined. You'll find a lil' extra power, but do it more as an experiment, which is what you're doing. The difference is gonna be negligible.

arghx

iTrader: (3)

You can't compare directly to the Renesis. The Renesis has primary, secondary, and aux ports controlled independently. The primary ports are controlled by the electronic throttle, the secondaries by a vacuum operated valve controlled by the ECU, and the aux ports by a motor controlled by the ECU.

The FC has the secondary ports controlled mechanically by a linkage connected to the primary butterfly, and the aux ports are controlled by backpressure on the s4 or pressure from the air pump on the s5 (controlled by a solenoid).

zak rabbit

By no means was I trying to "slam" the S4/S5 system, as I understand it, the OP is attempting a system that operates like the Renesis to see if there can be gains made "under the curve" as opposed to peak hp. I myself am debating making an intake with 6 separate butterflies to accomplish this.
I'll be watching this thread to see what the OP comes up with.

AbortRetryFail

Couldn't you do it with the existing valves? There's already two sets of butterflies on the throttle body for the secondary runners. In stock form, the front set is held mostly closed by vacuum. A little bit of modification should get those to close completely.

You'd want to make sure they're always open when the ECU switches on the secondary fuel injectors though or you'd be spraying fuel into ports with no airflow.

j9fd3s

iTrader: (3)

thats a good point. you could move the vacuum for those from the thermo valve, to manifold vacuum, and add a solenoid. i guess you'd really need an ECU to take advantage

jjwalker

With the 6 port NA primary ports being as small as they are, wouldn't the engine choke out some if you needed to floor it for whatever reason? The reason I ask is because the primaries on the NA are tiny compared to the 4 port turbo primaries.

Also, to the poster above you, he was asking about the 5th and 6th ports that open via backpressure or the air pump.

j9fd3s

iTrader: (3)

well presumably you'd have the ecu open the secondaries when its needed, either by rpm and or load. you'd need to spend some time tuning to see when/where they would need to open.

as we know the S4 ports open with exhaust backpressure, and this seems dumb, but works quiet well, as they open on demand. the S5 uses the air pump air, and also open on demand, although it takes an ECU output and a solenoid to do it.

the Rx8 uses a solenoid and vacuum actuator, so its not pressure. the Rx8 also has position switches so it knows if the ports open or not.

AbortRetryFail

Yeah some kind of control mechanism is sort of a given. You could always do it on the cheap with an RPM switch.

On the RX8, the secondary shutter valve (SSV) is controlled by a vac actuator and a solenoid, but the aux ports are on a stepper motor and position sensor (APV), presumably to allow the ECU to control exactly how open/closed they are.

If i ever get a decent CAN sniffer i'll have to see if i can find the sensor value from the APV.