My plans for the exhaust on my N/A are a little on the expensive side, and from what I can see completely unique. I'd like to take a Road Race header (duals), to a section replacing the RB R.R. pre-silencer comprised of 2 random tech metal matrix cat. converters custom piped (friend with mandrel bender), and brought back to the rear piece of the RB. The engine will eventually be aux bridgeported with the goal of oh, maybe 230 to the wheels. I personally see 2 metal matrix cats as the only setup that will survive use without the air pump, and should be able to keep emissions down with the dual setup as well. I don't have to pass anything but visual, so I'll still be putting on and taking off parts periodically to get that sticker, but what do you guys think about this exhaust plan?

Edit: I want to stay emissions legal for if (when) my area does eventually get smog, but largely for the lack of smell, stifling of flames, etc. Opinions on if it is worth it or not are not wanted here. I am looking for opinions on if it will fit, if they'll keep a 1/3 bridgeport (modified aux sleeves hopefully closing most or all of it) smog legal, etc. I realise I will probably have to rig something up for the ports based on lack of back pressure and air pump.

 

I am not familier with the Metal Matrix cats... are you sure they can be used on a rotary??? remember peak temps at the exhaust ports can be considerably higher than a piston engine that has a head to cool down the exhaust before it even hits the manifold.

Bonz cats normally are the only cats other than OEM that hold up any length of time on a rotary.

 

A few people now have put the Random Technology universal fit Metal Matrix cat on a single. There are a few threads on them around here somewhere. The supporters of them, along with Random Technology seemed to think that they would work fine. It was some hopeful thinking (and not disproven) that on a single exhaust with a 3" Random tech MM cat it may hold up to non-air-pump use, and still pass emissions. The guy who had it tested w/o the air pump barely failed cali standards, and passed either with the pump hooked up or running alcohol, I forget.

Edit: Here were some of the threads, they have links to any of the others that I read. A large cause for the desire to run them is their 4" total diameter.


https://www.rx7club.com/showthread.p...etal+substrate

https://www.rx7club.com/showthread.p...dom+technology

 

Is anyone familiar with metal substrate catalytic converters?

 

just dont run a cat or hollow it out

 

Heh, yeah. Point made.

 

how does that help him stay emissions legal?

 

[QUOTE= I want to stay emissions legal for if (when) my area does eventually get smog.[/QUOTE]





guess ppl just read parts of the threads lol

 

I'd just have a cat cut and rewelded over a straight pipe if I wanted to do that. I'm still interested in this, though and by the time I put them on my car hopefully there will be more informtion from people using them w/o an air pump. If a single lasts for even a while, I imagine two would fair well. Do you guys agree with that logic, or is that not quite how it works?

 

What about running the setup you initially spoke of only when it's smog time and then snag some straight piping for everyday driving.

Most places only smog every couple of years, right?

 

I've definitely thought about it, but for that purpose I wouldn't buy such expensive cats... I want some that I could run like that continuously but not have to hook up the air pump (which i'll have to throw on for emissions whether I hook it up or not). Basically I want to be able to run straight pipe or cat'd without the air pump. I said that I didn't want to argue about if it was worth it because I intend to run straight pipes inspected stock right now, but I'd like to not have to worry about it unless it's because I want to shoot fire. I'd rather have to work on my car to do something I want than something I have to do, I enjoy it more.

 

Dont you need the air pump to open the aux. ports?

 

the aux ports on this engine are gonna be a custom job anyway, I'll get 'em to work.

 

Yo! The "RoadRace Header" has a U-pipe that provides back pressure for your 5th & 6th port actuators. U don't need to worry about that. Just get a cheater catalyzer pipe for your inspection.... try the alcohol trick as well from what I've heard.. Never had to worry myself... I got the complete RoadRace system & love it.

Ramses666

 

I really wouldn't rely on exhaust pressure to open the aux ports. I use an RPM switch and a Ford lumbar pump (really cheap on eBay) to open mine.

I'm going to be having a true dual system made for myself pretty soon that has a replaceable section of pipes, so I can have a section with cats and a section with presilencers, and swap them out as I need. The only reason I'm doing it that way though is so I can legally get the system done, as no shop within 50 miles of me will touch it if I don't get cats put on. We've go no emissions tesing in MN so as soon as I get it home I'm bolting on the section with the presilencers and ripping out the rest of the emissions stuff, but I'll be keeping the section with the cats just incase. There was a guy selling dual inlet/outlet cats for $50 on ebay last week, but he's not anymore and I can't find any others.

Anyway, good luck.

-Darren

 

I hate Minnesota's laws due to emissions work. I know a shop in Detroit Lakes that will custom work. Just don't recommend him to anyone else .

 

Detroit Lakes? Dude, I live in North Branch but I'm heading up there in a couple weeks! Wasn't planning on bringing the FC with me though. What's the name of the shop?

 

Once Unicell quits acting stupid I'll post it tonight, I'll call my friend and see what the name of it is. They did his exhaust on his Duster without any cats or the like, hopefully he can do the same for you!

But it'll be posted tonight.

 

Didn't the Duster come without cats to begin with? They can legally do a system without cats for a car that didn't come stock with them.

 

Hey Turbo7MN, talk to AeroRx-7 and ask him where he has his exhaust work done. They'll do just about anything emissions legal or not if you pay cash.

 

I think he did reccomend me a place in Apple Valley a while back, but he thought it would be about $400 as well, and it's a pointlessly long drive for me. The place that's doing mine is in Forest Lake so it's not too inconvenient for me. Ah well, I'll have the cash as soon as I get paid for my wheels and hopefully by next week I should be happily destroying wildlife and shooting flames .

Than again, that's not the first time I've said that

 

The Duster didn't, but the guy is a friend of ours and would probably help. Unicell is still sucking.

 

Forget about it. I'm gonna be talking to a guy this weekend that builds off-road dune buggy type things that obviously don't run any cats. I'm gonna find out who does his exhaust. Also, it would be way too inconvenient for me to take my FC up there.

 

Ah, good luck!

 

I think I may have set my mind on RB header to presilencer to corksport catback w/ borla XR-1 right after the pre-silencer, and if that's too loud for me (doubtful) I'll be replacing the corksport muffler with another XR-1