1988 n/a gtu puting rebuilt motor in and while the cats were out i thought it would be a good time to empty them .but heard that it would not have enough vacum to open 6th ports ? and would be loud help .

 

if you just punch out the cats and still use stock mufflers its not really loud at all. i ran my car for a year like that and the pigs never bothered me it gives a wierd sound kinda tinny with punched out cats but if you don't have to worry about emissions and all that **** i'd just weld in a straight pipe from your manifold to your Y pipe it acually sounds really good. About your 6 ports someone just asked something similar to this the other day do a search on that.

 

That is correct the 5th/6th ports rely on backpressure to open. Gutting the cats takes away the backpressure.. Yes it will be loud. If you want performance and a decent sound recommend putting on cat/presilencer system. rx7doctor
Sorry it's supposed to say cat replacement pipe/presilencer.

 

it will not be loud. guy around the corner from me has a 100% stock S4 with gutted cats and he revved it to 8500 and it wasn't loud at all. i am assuming that you'll have the stock mufflers though.

 

Yes, it will be louder. Not a lot, but definetly louder. You will have more power. And, you will need to find another source of pressure for your ports (I just used a tap-off at the air pump outlet hose, with a small "regulator" hole at a "T" in the hose run)

 

^^ not true, im running a gutted main cat and a shitty catback and my ports open just fine, maybe 200rpm later than before. not a big deal.

 

thanks guys im gona remove all the rats nest and air pump also . we dont have to pass emmisions here.

 

What do you know, i have socks older than you,lol. Besides in Hawaii if you rev your car past 200rpm you would be excedding the speed limit,lol. rx7doctor

 

i think your forgetting how old your car is man.. dont belittle me because of my name! im 18.. haha but yeah, the roads suck here, except for H3, the one freeway usually void of traffic.

 

He's not belittling you he is just stating facts aboutthe age of his socks!!! I have the same problem.

How is exhaust affecting the vacuum??? I am almost certain (almost) that the ports open from vac. Exhaust would have nothing to do with it. Wayne88 said different meaning I am probably wrong.

Set me straight if I am wrong.

 

Ok let me set it straight.
(not that stupid juvenile "socks are older than me"--haha--NO not funny grow up and talk cars-otherwise be a ricer{not intended to flame but grow up if you don't have anything USEFUL to input.})
Wayne is correct saying you need backpressure from the exhaust--either that or as i also highly reccomend you doing is what wayne said about a t-adapter on the air pump hose and routing that to the way of your aux. ports. That is by far the simpelest way of doing it and it works perfectly.
Cake.
Matt

PS. the ports don't open on vaccum, the open on about 4-6 psi of pressure created either by the backpressure of the exhaust or on S5 models vaccum hose routing intake pressure to the ports. So nope, it's not vaccum

 

I have found that 2-3 psi is what takes the 5th and 6th ports to open. That is why when to buy a racingbeat header and presilencier, it has a adater so you can use the air pump to create the 2-3psi. So its not a good idea for an na to get rid of the air pump. You need that. I also have a customer with a S5 na that I got rid of the cats and the 5th and 6th port that open on time. Refer to your fsm.
Thanks Robert

 

That is cool. Learn something new seems every week. Is it a mechanical thing or does it use a pressure sensor and an electric actuator??

Marlaman, the socks thing is just a joke. I've read some funny **** on this forum.....and I enjoy it.

 

i hope you are not referring to me when you are stating about juvenile statement.
If you are i posted the correct facts about the operation of the 5th/6th ports.
You do not run a air pump when running the Rb header/presilencer system because it creates the correct amount of back pressure. If you are not running the presilencer then you will need to run it off the air pump to create the proper amount of pressure to open them. Or just wire them open if you want to.
If you are not referring to me than we don't have a problem,lol. rx7doctor

 

Sorry to correct you Robert. The presilencer has the nipple off of it to attach the line from the back of the intake that feeds pressure to the 5th/6th ports.
It's designed to create the correct amount of backpressure to open the ports.
It is recommended that when using the Rb system that you remove the air pump and acv and block it off with the included plate. rx7doctor

 

Doctor, I think Marlaman is having an off day, usually he is very sociable.

 

I had my Racing Beat header put on yesterday with a per-slicencer and RB cat-back, it idles low but when you step on it, its gets very loud, lots of vibrations, very deep, i guess i have to get use to it.

 

congratulations...


let me try to clarify how the 5th/6th ports work..

on the s4's: there is a tube attached to the catalytic converter. this tube feeds exhaust backpressure up to the actuators, which are only effected when it gets enough air pressure (about 3psi) which just happens to occur at around 4k rpm!

on the s5's: a more failsafe system was designed for the s5's, as long as you want to keep the airpump. at the correct rpm, the ecu sends a signal to a solenoid, which opens a line from the airpump to the actuators, opening them.

 

anyone successfully made an electronic actuator setup yet?

 

double post,

 

heres what i was thinking for when i remove my cats and would loose function ality...


edit: i meant 50 percent **** or 5 "psi" at 100 percent ****...

 

I took the cat's out on my '86 and replaced them with a bonez straight pipe, kept the stock Y and hollowed out the rust cans at the rear. 5th/6th ports open at about 3600, sounds nice too.

 

Rx7doctor I have to correct you. Once again J/k
If you talk with Jim taner at Racingbeat. They kept the nipple with the presilecier so you can keep the Actuators open at its correct time. They said there is no need to get rid of the acv. The racingbeat header and presilecier was design to work like factory. Also did you look at the reference to show you that the injectors Im selling are High impedence not Low..
Thanks Robert

 

Thats strange, why do the tell you to remove it and give you the block off plate with every header purchase or cat replacement /presilencer?
Yes i did look at the info, still pondering at this time, thanks. rx7doctor

 

Keep on poundering. I think you should have a talk with Jim Tanier or Jim meter.
Thanks Robert