SnatchedHatch Posted January 13, 2014 Share Posted January 13, 2014 (edited) I have to get an emissions test in my area, and I just passed mine. Fast forward a few months and my center cat is rattling like crazy. Sounds bad and I assume it's toast, needs replacement for my next test. I'm cool with putting it off for a while, especially if it means I can do something about my way to civil muffler. At this point, I'm not shelling out to replace the econo can with a cherry bomb, I had to get a muffler and I'm not fixing what's not broke at this point. I thought, my guy could cut out the cat and weld some pipe in place, or better yet: I have heard of chamber(s) being used in aftermarket exhaust setups to "boost" the sound. Is this feasable in an 87' GL hatchback setup? Would I have some kind of backflow issues? It's just some something I cooked up when I had too much time on my hands haha Edited January 13, 2014 by SnatchedHatch Quote Link to comment Share on other sites More sharing options...
Loyale 2.7 Turbo Posted January 13, 2014 Share Posted January 13, 2014 I removed both catalytic converters on my EA82 wagon more than twenty years ago, and welded there straight 2" pipes, the thing has been working awesome since then, it improves the exhaust flow (faster engine response times) and decreases the workin' temp a little, while adds a louder tone, but I don't need to pass emission tests here. So, since EA82's and EA81's are pretty similar, I bet that welding a straight pipe there, is the way to go; 'till you can obtain another catalytic converter; maybe a junk yard one in good shape will be enough. Kind Regards. Quote Link to comment Share on other sites More sharing options...
skishop69 Posted January 13, 2014 Share Posted January 13, 2014 Removing the CAT won't do anything for your sound, and very little if anything for your performance. If you want to be on the safe side, you can take off the Y pipe, take a steel rod, run it through the end and beat the living daylights out of what's left of your CAT. Dump out the debris and done. This will prevent it from possibly plugging your exhaust. As for junkyards, none sell used CATs. Thank you EPA..... Quote Link to comment Share on other sites More sharing options...
Loyale 2.7 Turbo Posted January 13, 2014 Share Posted January 13, 2014 Well, when I first removed the Cat located in the middle of the "Y" pipe, plus removed the Cat at the middle of the Pipe, the Exhaust sound of my EA82 changed a little to a more deep burbling sound, despite that the Subie still ran with its original muffler for a while. ... As for junkyards, none sell used CATs. Thank you EPA..... I didn't knew that... Kind Regards. Quote Link to comment Share on other sites More sharing options...
scoobiedubie Posted January 14, 2014 Share Posted January 14, 2014 The car will pass emissions test without the middle cat. Mine did. Naturally you would like to have new plugs and have recently checked the timing, cleaned off the corrosion inside the cap, checked your plug wire ends for corrosion, prior to your next test. Quote Link to comment Share on other sites More sharing options...
SnatchedHatch Posted January 14, 2014 Author Share Posted January 14, 2014 Once again, I got more than I bargained for! Thanks for all the great advice, I need to check the FSM to see if getting at the plugs will be simple or not. Haven't worked on a boxer before :/ Any advice in short, I've heard some engines can be a pain. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted January 14, 2014 Share Posted January 14, 2014 The car will pass emissions test i'm not sure that all state's emissions testing are identical, it may vary? it might not pass the California whackadoos getting at the plugs will be simple or not. they're cake. my center cat is rattling like crazy it's probably just the heat shields and your cat is fine. Quote Link to comment Share on other sites More sharing options...
Greenley Posted January 15, 2014 Share Posted January 15, 2014 (edited) Removing the CAT won't do anything for your sound, and very little if anything for your performance. This is false. The audible difference is incredible! Of course it all depends on what you've got downstream. And naturally, an unrestricted flow will always enhance performance, whether intake or exhaust. you can take off the Y pipe, take a steel rod, run it through the end and beat the living daylights out of what's left of your CAT. Dump out the debris and done. This will prevent it from possibly plugging your exhaust. Listening to this advice is a sure fire way to clog your exhaust. What about the mesh screen that surrounds the honeycomb? I tried this, and ended up having to cut the pipe directly behind the cat, and pull said screen apart with pliers in order to get all the chunks out. They dont just dump out... my center cat is rattling like crazy. Sounds bad it's probably just the heat shields and your cat is fine +1 Edited January 15, 2014 by Greenley Quote Link to comment Share on other sites More sharing options...
SmashedGlass Posted January 15, 2014 Share Posted January 15, 2014 (edited) Another +1 for heat shielding. A clogging cat won't rattle, but will smell like flame-roasted kittens. And I made the mistake (?) of buying a Y-pipe/cat with heat shield, instead of without, and within three weeks of installation that damn thing was rattling on acceleration. Never again, I'll wrap it with DEI next time. Edited January 15, 2014 by SmashedGlass Quote Link to comment Share on other sites More sharing options...
skishop69 Posted January 15, 2014 Share Posted January 15, 2014 Sound: On a stock system, there is no audible difference. Especially with the CAT so far upstream. Been there, done that on too many rigs to count. Performance: Again, with a very low HP engine, and built in designs for scavenging, you will notice no appreciable gain in power by gutting or removing a correctly functioning CAT. What screen? Gutted all 3 of my Brats and my XT GL-10 along with countless other vehicles and have never ran across a screen surrounding the substrate. I fail to see this clogging anything if you rod everything out. A clogging CAT CAN rattle. If the center of the substrate starts to fail and melt, the exhaust will be forced to flow around the melted section increasing heat around the casing causing it (the substrate) to burn up and separate from the casing. Not very common, but possible. The heat shield is far more likely though. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted January 15, 2014 Share Posted January 15, 2014 SWhat screen? Gutted all 3 of my Brats and my XT GL-10 along with countless other vehicles and have never ran across a screen surrounding the substrate. I fail to see this clogging anything if you rod everything out. I've gutted a cat in this manner before as well with no issue. If you break into small enough crumbs and there aren't massive caverns, turns, and hangs up in the exhaust somewhere it should all come shooting out. It was fun watching all the propellant shoot out the back the first time i started it up. LOL Quote Link to comment Share on other sites More sharing options...
Greenley Posted January 15, 2014 Share Posted January 15, 2014 The mesh/screen im speaking of must only be in California specific cats, as i've seen this screen in the two that i've gutted. It added a definite element of "fun" to the process. Sound: On a stock system Performance: Stock system, mayyyyybe. But what fun is a stock exhaust system when you live in the sticks? My butt-dyno and ears beg to argue this one. Quote Link to comment Share on other sites More sharing options...
skishop69 Posted January 16, 2014 Share Posted January 16, 2014 Saweet! Where did you have your butt-dyno calibrated? I've been meaning to get mine done. I think only 2 of my rigs still have stock exhaust so I get that. Can't do the Baja since the little lady drives it and the truck..... Well, I'm just not ready to shell out $600 for headers yet. Agreed. Gutting any CAT sucks. But unfortunately in some instances, there has to appear to be one there. Once that 25 year mark is passed... It's outta there! Quote Link to comment Share on other sites More sharing options...
SnatchedHatch Posted January 27, 2014 Author Share Posted January 27, 2014 Thanks everyone for the awesome input! I've dealt with a pesky heat shield on my Nissan before, drove me to the point of it. Down the line I regretted it, I guess I nicked the pipe in a spot and that snowballed But sweet relief it was. I'll check it out as soon as I can, which because of nuisance I'll speed up, cold and wet or not. Last time I had it up on the lift, a buddy of mine told me I probably gave it a solid knock while taking it off the trail and broke some particle loose. I cannot deny this claim lol, Ferris Bueller's day off Ferrari scene comes to mind Quote Link to comment Share on other sites More sharing options...
SnatchedHatch Posted January 27, 2014 Author Share Posted January 27, 2014 (edited) Whether or not it's plausible, I hope that cat is due fro replacement. I'll chop it out and take off the muffler, for now heeheee Emissions testing is 11 months away so I give no f$#ks For the record, the muffler made a noticeable loss of power, and you guys seem to be split on the loss of one cat. I'll post updates as they come Edited January 27, 2014 by SnatchedHatch Quote Link to comment Share on other sites More sharing options...
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