How do you unclog or clean out your cat?

Posted by Eclipse98Spyder, Oct 18, 2006
Bolt-on Tech - 4G63 intake, exhaust, intake manifold, ignition, fuel system, cooling, etc.

  1. Eclipse98Spyder

    Eclipse98Spyder Proven Member

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    Searched and found ALOT of thread on this topic of clogged cats but none explaing how to clean them out. So my question is how do you clean them out? The process and whats needed and is involved? Thanks
     
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  2. staticbrainwash

    staticbrainwash Awaiting Email Verification

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    You can't really clean a clogged cat. It's pieces of metal inside of it. Once those metals reach a certain point of "burn up" or "cleaning potential" they break down some. That metal can still be reclaimed because of it's precious nature. But you can't "clean" it.

    Just look at getting a new OEM cat, OR pick up an aftermarket one with a carb certification.

    If there's a way to clean it, then it beyond me. Usually you just replace a clogged cat and call it a day for another 100k or so.
     
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  3. 92awddsm

    92awddsm DSM Wiseman

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    There are 3 ways to remedy a clogged cat.
    1) Steel rod through the center
    2) Test pipe
    3) Replace the cat with new.

    The catalytic converter contains a ceramic catalyst, not pieces of metal.
     
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  4. Eclipse98Spyder

    Eclipse98Spyder Proven Member

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    Test pipes in PA thats a no my last car got nailed for it so did my wallet for the ticket
     
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  5. 1stGenRocks

    1stGenRocks Proven Member

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    ceramic honeycomb coated in precious metals like platinum which eventually it all melts and blocks the holes in the honeycomb. so your both right.
     
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  6. staticbrainwash

    staticbrainwash Awaiting Email Verification

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    Thats what i meant, sorry. When i said breaks down. . . yeah. Sorry i wasn't that clear.

    But you all got it more or less.

    As an N/A gutting the cat may be ok. I wouldn't recommend it for a turbo car though. But if it were me, i'd just replace it and call it good for a while.
     
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  7. 4g64GST

    4g64GST Proven Member

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    If it clogged there is a reason, find out that caused it or the new one will do the same.

    example:
    rich- unburnt fuel firing off inside the cat melting it down.
     
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  8. 92awddsm

    92awddsm DSM Wiseman

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    Just out of curiosity, why do you not recommend it on a turbo car?
     
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  9. staticbrainwash

    staticbrainwash Awaiting Email Verification

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    Because of the flow characteristics of a turbo car.

    "The best exhaust is no exhaust", under that principal you want as clean of a flow as possible. Hence why we opt for mandrel bending over press or crush bent.

    Think about it, you're going to flow a gas through a pipe, that pipe will then open up into a larger chamber, then close back down. Where that pipe closes back down the exhaust gasses will be trying to squeeze back down. Causing them to run into eachother, and into the walls of said chamber creating turblance. This turblance will hinder flow as the exhaust gasses continue to bombard around trying to go from big to small. Again, the same reason a press bend is bad.

    But in an NA car, you don't have to worry as much about this, because though it will increase flow to a point, it still will be creating back pressure.

    But if you're that worried and want a test pipe, just hack the cat shielding off, and tack it around the test pipe, so it looks like a cat.
     
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  10. HighPsi91

    HighPsi91 Proven Member

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    Gutting a cat causes turbulance and reduces flow, and power on NA or a turbo car. In alot of cases low rpm power will have a seat of the pants power increase however the overall result is a reduction in performance.

    If your cat is bad replace it, that is the nest solution.

    Gutting cats years ago when they still were filled with pellets offered a power increase because the pellet style cats were so incredibly restrictive. This just isnt the case with modern honey comb style cats.
     
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  11. 92awddsm

    92awddsm DSM Wiseman

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    Granted, the open chamber creates turbulance in the exhaust but the catalyst in the converter actually creates more restriction. Even with the catalyst still intact, the flow patten is almost identical to that of a gutted cat. The catalyst just adds restriction to the turbulence that is created by the larger chamber. Airflow through a gutted cat will surpass that of an intact cat. Turbo or non turbo, this still applies.
     
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  12. perley03

    perley03 Proven Member

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    Take the cat off, by a section of exhaust pipe that will fit inside of it. Ram the new pipe all the way through the cat, cut the ends so they are flush with the ends on the cat, and reinstall. Problem fixed. Looks like a cat is there, and really its just a test pipe. Done it on many cars, works flawless, looks OEM, and passes inspection.
     
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  13. Eclipse98Spyder

    Eclipse98Spyder Proven Member

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    May pass inspection but will the sound db be louder? I would almost assume so
     
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  14. No_Skillz

    No_Skillz Proven Member

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    My car going from stock dp w/ cat to 3in dp cat elim did not get any louder.
     
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  15. HighPsi91

    HighPsi91 Proven Member

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    Honey comb style cats have linear flow paths through the catalyst which keep the exhaust flow straight through the cat. Very similar to the honeycombs in our MAS's. Remove them and the air no longer flows as linear and causes turbulance.
     
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  16. 1stGenRocks

    1stGenRocks Proven Member

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    honeycomb cats flow straight through but then they have the same turbulence at the end.

    so the cat is oval in the middle and tapers down at both ends right? the honeycomb is only in the center full size section. The exhaust goes in a 2 inch hole. has a big cone expanding to 7 inches or whatever oval, goes through the honeycomb then comes out and has the same turbulence again as it all trys to go out a 2 inch hole.

    the honeycomb directs it STRAIGHT through it doesnt angle it towards the inlet/outlet or do anything to increase flow.

    when i gutted mine i wouldnt say it got louder but the tone changed. got a bit more agressive sounding and you can hear when the stock internal gate opens now.
     
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