Talde

correst me if im wrong but i dont understand how wiring them open, "you lose low end power" how is that possible if less air is comming in at under 4k. if you leave them open, wouldnt more are be comming in? therefore making more power? i just dont understand how less air makes low end power. idk. you can say the factory ecu is not programed to have more air in the combustion chamber so why not just make it run a tid bit richer? i know there some screw that i turned on my passenger side of the engine bay near the shock tower to lean it out or to make it run rich, variable resistor i think, i mean, you just letting a little bit more are into the chambers, its after the maf, so air flow reading wouldnt change, i have searched about the aux ports and i found no useful information to answer my question, all i get is, you leave them open=no low end but same top end, you leave them closed=low end no top end, then i get the, clean them and make sure they work right=stock, i know i might sound stupid but im new to the rx7. im just baffled about the aux ports. sorry if i sound like idk wat im talking about.

Project88Turbo

iTrader: (22)

Search harder for a post Icemark or NZconvertible put up with a dyno sheet from an SAE paper on the development of the auxialliary ports. It shows the point where have the ports closed versus open meets, and that just happens to be where they open from the factory since it is most effective. Having them open at the factory point results in the best performance.

The reason why you loose low end power with the ports wired open is intake velocity vs flow. The velocity is higher with the ports closed at low rpm, once the engine gets into the higher rpms the ports need to be opened as the added flow is needed.

At low rpm with the ports open, there simply is not enough air flow generated to need all 6 ports. The intake velocity is lower and the volumetric efficiency drops, and the fuel mixture doesn't get atomized as well as it would because with less velocity, there is less turbulance to evenly distribute the fuel in the combustion chamber.

^
The above is my theory based on that dyno sheet and my MINUTE understanding of fluid dynamics. Inaccuracies may exist, but I believe it to be correct conceptually.

Also, the variable resistor on the passenger shock tower only affects the IDLE mixture.

Vince

Aaron Cake

iTrader: (1)

Long story short, there's too much port timing and volume. You loose air velocity with all that port area so you get less filling of the chamber.

I'm not sure what this means. You want to make the car run richer? Why?

That's the idle adjust mixture screw. It only effects the mixture at idle. Since you messed with it, follow the instructions in the FSM (see the FAQ) to reset it where it should go.

Think of the aux ports as a variable cam.

Rx7TyreBurna

iTrader: (1)

It is like taking a huge straw and trying to suck water through it... I mean huge, 6 inch diam. Not going to be easy.... maybe if you had already built up some good pressure. With the ports closed, it is like trying to suck air through a 1 inch diam straw. Much easier.

Not a great analogy, but... oh well.

Don't tie them open. Mine were removed when the engine was rebuilt. Kills your low end, and you don't gain anything high up. If they aren't working, make them work.

Talde

when you look at my 5th and 6th ports from the passenger fender, the left one works well when you rev, but the right one is dead stuck with rust. so i only have one of the 2 working, i guess those posts answered my q's thanks guys.