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hollowing the catalytic converter

 
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Old 11-19-2007, 10:30 AM
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hollowing the catalytic converter

I'm thinking about hollowing it out. good/bad idea?
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Old 11-19-2007, 11:02 AM
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i wouldnt, it can actually hurt performance.
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Old 11-19-2007, 11:16 AM
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bad idea, 1. it'll be really loud, 2. u'll pollute the environment, and 3. really no gains from this
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Old 11-19-2007, 01:38 PM
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good luck on passing the emissions test in NY if you do that.
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Old 11-19-2007, 02:50 PM
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your all so negative, ha. So i wont do it then.
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Old 11-19-2007, 03:09 PM
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haha yea...ny you will DEFINITELY fail inspection but then again you can always pay the guy a little more to pass you...not as if you are obd2 and would have difficulties..

is your exhaust system stock?
i mean...a gutted cat will help free up air flow but youll be killing everything around you haha....so unless this is part of some much larger plan in regards to your air flow in and out.....id say no...

and yea loud and ricey as heck.
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Old 11-19-2007, 04:56 PM
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yeah not the best thing to do get like bigger exhuast piping and maybe like flowmaster thats what i got and its a really deep sound i just love setting off car alarms with my car its the best thing ever but yeah i had a friend hollow out his cat on a ford escort it made the car really loud and gave just a little bit more power not much and it messed the car really bad and it made it smell bad
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Old 11-20-2007, 10:04 AM
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its a good idea if you want to reach a new level of rice
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Old 11-20-2007, 10:55 AM
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So would hollowing it out, ruin/break anything?
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Old 11-20-2007, 11:20 AM
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hollowing a cat will cause issues with exhaust flow, reason is the cat isn't a straight cylinder or pipe.... the odd shape will cause back pressure and in most cases, hurt performance.

Just get a test pipe and stop being a cheap ass...

and avoid the flowmasters, they're terrible.
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Old 11-20-2007, 07:24 PM
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i wouldn't suggest hollowing it out, do what team123 said and buy a test pipe or make your own by taking the cat down measure the leangth flange to flange, cut the pipes before and after the cat and weld in a pipe to make it the same length it was before and wham, a test pipe! but not having a cat isn't going to hurt your car any, i haven't had one on mine for about a year now!
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Old 11-20-2007, 07:47 PM
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werd, so ill just remove it and put some pipe from like Napa on there.
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Old 11-20-2007, 11:58 PM
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if thats what you want, but just as a warning, with out a cat you're going to have carbon build up on your back bumper, it's going to be a scoach bit louder, and you probally wont pass NY emissions
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Old 11-21-2007, 12:17 PM
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If you want to get real tricky and you are bound to remove the cat then get a piece of pipe the same length of the cat and make it fit inside the cat so that you have a straight pipe going though it but it still looks like you have a cat. Just an idea.
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Old 11-21-2007, 02:17 PM
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thats what i was planning
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Old 11-21-2007, 02:30 PM
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Quote:
Originally Posted by btnhfool View Post
thats what i was planning
Like it was stated earlier, your rear bumper will be covered in black soot, if it's not already.

But by going with a straight pipe inside the cat, you cut down on the back pressure build up so you get better air flow.

Just good luck on passing the emissions test. I'm not sure what kind of test they do on older cars in NY but I know here in TN, they put a sniffer in the tail pipe to detect if you are burnning right on older cars, on the newer cars, they just plug up the computer.

The only advantage to removing the cat is you get about 3-4 more Hp. Disavantage; more carbon build up and black smoke out the tail pipe.
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Old 11-21-2007, 02:35 PM
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I'll pass inspection, i know a place.
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Old 11-21-2007, 02:39 PM
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I'll pass inspection, i know a place.
cool then!!
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Old 11-21-2007, 03:06 PM
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Quote:
Originally Posted by guessman View Post
Like it was stated earlier, your rear bumper will be covered in black soot, if it's not already.
LOL! so true!!

Quote:
Originally Posted by guessman View Post
But by going with a straight pipe inside the cat, you cut down on the back pressure build up so you get better air flow.
Yes, somewhat...i had a broken cat & no muffler when i picked up my Lude. I drove around like that for a week and HOLY crap did i feel the car move like a beast! LOUD and SMELLY yes...thank god for temp inspection sticker
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Just good luck on passing the emissions test. I'm not sure what kind of test they do on older cars in NY but I know here in TN, they put a sniffer in the tail pipe to detect if you are burnning right on older cars, on the newer cars, they just plug up the computer.

The only advantage to removing the cat is you get about 3-4 more Hp. Disavantage; more carbon build up and black smoke out the tail pipe.
Same here in NY...they test the car for hydrocarbons:

(that's illqueens)

that and they do a visual inpsection of the tires, brakes, wheels, front lights, indicators, windshield etc etc...
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Old 11-21-2007, 03:51 PM
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Sweet looking little red Lude you got there. Clean too!! nice. sounded great in the vid.
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Old 11-21-2007, 03:54 PM
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Old 11-21-2007, 03:59 PM
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my bad then. well, he has a sharp little ride then, pass it on
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Old 11-29-2007, 11:22 PM
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I've gutted several. If you choose to use a piece of pipe and hammer it through the catalyst. Then chisel out the remaining chunks. You have to break them in to small enough portions to exit the cat.
If you have the original cat chances are it's not in the best of shape. The catalyst material on my buddys 91 was literally melted in portions. Several months after removing the cat and gutting it I decided to replace the exhaust pipe from the cat to the muffler since it developed a large hole. I cut the piping off after the cat and found a large chunk of catalyst material almost completely blocking the pipe. It was right at the first 90 degree bend after the cat. I'm shocked the car ran at all!
There is a bit more of a rattle and resonance sound since the cat is a large hollow section with old rusty heat shielding. I don't think it hinders performance however. I like the peace of mind knowing the car can breathe.
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Old 11-30-2007, 12:29 AM
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If your cat is in such a bad condition, there's something else wrong. Cat's burn up the gases not fuel so they should go "bad" per say. Though if you find yourself in the same situation as the person above me, something else caused the cat to go out.

Could be running very rich.
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Old 11-30-2007, 01:27 PM
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Cats have a finite life. The car is a 91 w/b20a swap. I really don't know of anything mechanically wrong with the car that would cause a cat failure. I assume it's just served its time.
I suppose the b21 with those lovely frm sleeves could have douched the cat with oil for a long period of time. My buddy bought the car with the b20a however. I have no idea what the state of the b21 was prior to removal.
Its clear the cat became quite hot however.
It looks like lava rock. It's tough as hell. I actually went through 2 reciprocating saw blades before I realized there was something inside the exhaust I was trying to cut through. I had to use a cut off wheel.
The piece of once molten catalyst is lodged in the pipe. I cannot remove it.
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Old 11-30-2007, 03:20 PM
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Old 11-30-2007, 03:31 PM
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Damn, that is something else to see that crap lodged in the exhaust piping...:sick:
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Old 11-30-2007, 03:40 PM
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how the hell did it run with that **** in there
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Old 11-30-2007, 04:07 PM
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thats some crazy ****t right there!!!
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Old 12-01-2007, 12:45 PM
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I don't know how it managed to run as well as it did. The only holes I know of in the exhaust system were downstream of the blockage. I would expect the back pressure to rupture some of the exhaust gaskets but it doesn't seem to be leaking anywhere around the head to dc header or where the header meets the cat. There is a very small leak at the location of the egr allocation on the header. It's been welded closed (mostly) by someone while still in the car and it seems they could only reach so much. That's only on one runner and a very small leak.
I can say it's much much more peppy with that hunk of garbage removed.
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