Ok well I went auto X today and I cracked my exhuast open again right at the frt cat where it is welded to the flange that bolts to the stock manifold.

anyway I pulled the convertors and was gonna inspect them and maybe bash them out, and this is what I found..

the main cat (with the air tube) has a crack on the outside across the entire convertor right up to the air tube, the first cat appears to be plugged but in good physical shape.

I dont have any emissions laws and currently I have dual stock mufflers, I was planning to make a custom pipe roughly 2 1/4"-2 1/2" and weld it to the stock flanges, and then drill a hole in the pipe and weld the air tube to it (to keep that functional.

what do u guys think? this is on a 86' N/a 13B 5spd, I am wondering if it will be fine, maybe a bit faster, should I remove the air tube intirely or keep it or what?

Dave

 

Well I can tell you this. I removed all my CATS and I have Headers running to the Y pipe and out to Aerospeed Mufflers. Its loud as hell. So I had a resonator put on and its even louder now. As far as the 5th and 6th port activation. I am using an aquarium valve that is tapped into the air pump and after playing with it for awhile I have it opening the ports around 3500 RPM. But the damn car is so friggin loud that I am strongly concidering putting a CAT back on there.

 

well it cant be any louder then when the pipe is broke off right at the header, I dont mind loud as long as u can have your radio on and enjoy it

and u said it is louder with a resonator?

Dave

 

+1
Before i installed a cat and 2 resonators, my exhaust would set off car alarms :/

 

Racing Beat mufflers.

 

Well, if you want to keep the aux ports operational, you either need to use a stock cat, get the racing beat downpipe(or header) and presilencer setup, or use some type of method to open the aux ports another way.
The best way to do it would be to get the racing beat stuff. If you have the money, I would get the header and presilencer. The downpipe connects right up to the stock exhaust manifold and is cheaper, while the header replaces the stock man (duh). If you want to go that route I actually have a the dp for sale, but I already sold the presilencer.
The cheapest way to do it would be a cheapo test pipe and having some other way to open the aux ports. Whatever you end up doing, keep the aux ports operating.

 

you want loud. I am running with no cats, R/B headers and presilencer. Also I have a single 3 " pipe (made in a muffler shop) and x/p performance muffler. Lets just say I dont bring it over 3000 rpms when driving home late at night. I will be getting a resonator. It should quiet it down. The single pipe gives me more power because it reduces weight. But it just too loud.

 

No, it doesn't. It gives you the same power as any other decent catback for our cars. It is maybe 50 pounds lighter than even a heavey dual system which is hardly enough to make a noticable difference on a street car. And if you want loud, try running with nothing but the exhaust manifold. That is loud.
Anyway, I just noticed that corksport is about to start selling a header that bolts straight up to the stock cat.

 

you want loud heres loud, straight single exhuast no cats no resonators just one crapy hiflow muffler and the stock manifold. i can raddle windows at 4000rpms passing cars.

 

My normal setup is the rb header/presilencer and apex n1 catback, and its pretty loud. But nothing, except maybe an open header, can be worse than just the stock exhaust manifold. It was even worse since I have a ported intake and exhuast. I had to run that for a few days because the studs broke off the stock man. and I was waiting on the header to come in. I only floored it once and my ears were ringing for several minutes. It would set off car alarms several blocks away just by turning it on. Never again....
While we're talking about loud, my uncle's super-modified testarossa was so loud it shook a nieghbors picture off the wall. They thought my uncle was remodeling his house and was knocking out a wall.

 

what the aux ports wont work unless it is attached to a convertor?

I was gonna just drill a hole in the pipe I make and weld the air tube to it that should make it functional again right?

now I was looking at a racing beat downpipe and silencer, but if I read this right this is ONLY the downpipe right? or have they combined them and u get the down pipe and the presilencer?

http://www.rx7store.net/product_p/rbdownpipe8691.htm

if it is both I will buy that this weekend and mount that to my stock cat back for now

Dave

 

It's only the down pipe. The down pipe and presilencer from Racing Beat is $305.

 

no, I dont think so. There would be next to no backpressure if it was set up this way, not enough to open your ports anyway. (Correct me if I am wrong) You would be better off activating your ports using the air pump, then you dont even have to worry about it either way.

 

oh so that is done by back pressure then gottcha..

now I am thinking of removing the first cat and keeping the second one (with the pipe on it)

will that be fine?

also how do u open your aux ports with the air pump?

Dave

 

well my convertors are both plugged, can I just buy a resonator and then drill a hole in it and weld the bung to that? will that give me enough back pressure to work the actuators?

otherwise how do I make the actuators work off the air pump?

Dave

 

https://www.rx7club.com/2nd-gen-archive-72/how-air-pump-auxilary-port-activation-330310/

 

no cats means they cant clog up and cause your engine to catch a flame =)

 

What about heat wrapping the exhaust manifold?

 

well both my cats are toast, I have hollowed the one out, the other I am in the pocess of hollowing out then I plan to put them back up for stock appearance sake

Dave

 

i wouldnt worry too much about your 5/6th ports, just wire them open, i can barely tell the difference with them wired open or closed at low rpm. and i still get 21 mpg city with them wired open.

 

that was another option.. if I wire them open what will I really loose or gain by doing this?

will it harm the engine will I loose "that much" low end?

Dave

 

I used zip-ties to hold mine open, just for curiosity's sake, I noticed a big loss in low rpm torque. I wouldnt reccomend doing it, myself.

 

well I was considering buying a new rear cat (with the air tube) cost is like 90ish however I dont know if I want a new convertor or if I want to go with a presilencer or something like that.. either way I would perfer to keep my aux ports operational if possible

Dave

 

U can get a high flow cat from many companies with air tube for under 100 bucks. Alot of times RX7's exhaust sound loud with aftermarket pipes because the wall thickness of some aftermarket pipes are very thin, making you have tinney sounding exhaust. A good muffler shop can make up some good thick Stainless pipes wont sound riced out. My car sets off alarms, but because of the low frequency sound (turbo with 2.5 inch dp and exhaust (Duals) )

 

well I am thinking of just going with the racing beat convertor pipe and silencer

Dave