Tyblat

Hey guys. I know the 5th and 6th ports open when the backpressure is significant. I was thinking of removing my airpump and gutting my cats, and im just worried about if that will effect my 5th and 6th ports from opening up at all. Can anyone help me out on this one?

crazyasu

if u gut your cats your ports will not open...

Tyblat

are you 100% sure on that? How can anyone change their exhaust on an N/A S4 if that would be the case?

if thats true (not saying it isnt) how would i get my ports to open?

Alex6969

electric port actuation my firend.

crazyasu

I am 100% sure...and also...zip tie's myfriend...they work wonders...

Tyblat

so, if I gut my cats, the ports wont open at all? no matter how high the rpm's get on the engine?


what would you say the consequences are of the 5th and 6th ports not opening.

crazyasu

u will lose that additional air necessary for maximum engine performance @ higher engine speeds.

importsown

If you straight pipe/gut your cats they will definately not open. I know from firsthand exp, learning about 2 months after buying the car they werent opening. Just tap into your air pump, the line that runs right near it. Just search, or go to my thread @ https://www.rx7club.com/showthread.p...80#post5782980 and look at the pictures. Hope this helps.

synesthete

Theres no reason that gutting the cats is gonna make the aux ports not open.
They might open later but not by much.

If they dont open after gutting the cats you probably created a leak somewhere, or didnt hook the split air pipe back up right.
If a presilencer can open them, than gutted cats surely can.

Many people have done it and not had a problem.

synesthete

There is a huge difference between a straight pipe and gutted cats.

Straight pipe = NO SPLIT AIR PIPE
Gutted Cats = STILL THERE WORKS FINE.

The split air pipe is what makes the ports open, as long as it is still there the auxiliary ports will work.

To the original poster, I'm sorry that your post had replies from 3 different people all saying complete BS. You'll find that subjects like this that have been covered many many times will often be overlooked by anyone who knows what they're talking about. I reccomend searching next time.

Sideways7

iTrader: (7)

That isn't true. You have to have exhaust backpressure to open the ports, so the split air pipe doesnt do anything if theres not enough backpressure. When I bought my car, the aux ports didn't work because it had the bonez midpipe on it, which has a nozzle that works the same as how the stock system works. Since it had a large catback on it, there wasnt enough backpressure to open it. Now if you keep the stock cat-backs you should still have enough backpressure to open them, but they will prob open later than inteneded which will effect the power delivered. It will still be much better than wiring them open, though.
Also, the way the RB presilencer works is different from how all other systems works. It actually has a pipe inside the presilencer facing toward the engine that captures exhaust gases to open the ports regardless of backpressure.
If it were me, I'd just gut the cats and see what happens. If it works great, if not, you can wire it open or do electronic actuation.

crazyasu

S4 engine...exhaust back pressure...period...LOOK-IT-UP...and I recomend u check your facts before u post...

importsown

Oh god, please got read the ENTIRE thread that i posted earlier. It explains everything. And take my word for it, hook up the aux. ports involved with the 6PI to the air pump. Then you dont need a cat/presilencer/gutted cat or whatever. Period.

Oh and i do understand why icemark made such a big deal out of the term "backpressure". No it just drives me nuts when someone explains it like that.

"They run off backpressure..."

ARGH!. lol.

Tyblat

I searched all over the forums...and I found a bunch of sides all saying different things haha. I'm not saying each and every one of you guys are wrong..but damn who do I listen to? Lol

synesthete

So when the exhaust creates a certain amount of backpressure the ports just magically open up right? Like the car senses thru telepathy how much backpressure exists.

I dont think you understand what the split-air pipe is actually there for. I was trying to avoid using the term backpressure because people want to debate that term, because it is not exactly correct. The split air pipe allows the aux ports to open once the pressure in the cat (and therefore the split air pipe) reaches a certain point.

With no split air pipe, there is no backpressure as far as your 6pi is concerned because the split air pipe is how it measures it.

There is no split air pipe on a custom straight pipe so the 6pi will not work in stock form.

There is a split air pipe on gutted stock cats so the 6pi will work as long as you dont have free flowing exhaust or whatever behind it. There may be a slight difference in when the backpressure builds to that point but im guessing it is not going to be dramatic in most cases.

Think of the split air pipe as like an exhaust pressure sensor.

importsown

On S4 engines the split air pipe is ALSO the source, not just a "sensor" as you describe. On S5 engines the split air pipe serves as the "sensor" if i remember correctly. I forget how exactly it works, but the actuators actually run off of your air pump I THINK on S5 motors.

Correct me if i am wrong plz.

ROTARYROCKET7

RB presilencer for s4 gxl has an extra pipe that provides back pressure to the 5th/6th ports for actuation lol.

Jason NYC

crazyasu

I just recently got rid of the stock exhaust...ran 2-1/4" pipe...removed the cats... put in a high flow res & re-attached the split-air pipe...my aux ports were opening up fine before I decided to do my new exhaust...now they won't opened...done the grease test twice...nothing...so I zip-tied them opened...didn't notice hardly any low end loss @ all...but what an increase in the top end...Daaammnn...
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