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Topic Review (Newest First)
01-23-2011 04:30 PM
Bubba68CS
Quote:
Originally Posted by MikeMYJ View Post
I say don't skimp out on something like a CAT, and just replace it. Not saying you will get caught, but there is always a chance. The fine is going to be a lot more than what the CAT will cost. Not only that, it's better for the environment.
Agreed...no reason to get rid of them. And if I recall correctly, the high flow cat I put on my Camaro back in high school wasn't that much more than the replacement - so if you want that option, ask your exhaust guy. On that note however, I actually didn't like the sound as well after installing that. I had headers and a cat-back Borla on that Camaro and liked the sound better with the stock converter. But for those looking just for a volume increase - it definitely achieved that.
01-23-2011 04:17 PM
MikeMTJ I say don't skimp out on something like a CAT, and just replace it. Not saying you will get caught, but there is always a chance. The fine is going to be a lot more than what the CAT will cost. Not only that, it's better for the environment.
01-23-2011 04:08 PM
Bubba68CS
Quote:
Originally Posted by UnlimitedLJ04 View Post
Ahh, the truth comes out....your definition of a muscle car is a pre-1973 non-catalyst car, with a big gas drinking engine that rumbles nice with dual pipes, but is not necessarily as fast as new catalyst vehicles today, and has absolutely nothing to do with this thread's topic of catalytic converters on Jeeps.
Hey, I wasn't the one who brought up muscle cars in this thread. Simply pointed out that REAL muscle cars () never had cats to begin with.

01-23-2011 04:05 PM
UnlimitedLJ04
Quote:
Originally Posted by Bubba68CS View Post
And yes, I am absolutely a muscle car snob.
Ahh, the truth comes out....your definition of a muscle car is a pre-1973 non-catalyst car, with a big gas drinking engine that rumbles nice with dual pipes, but is not necessarily as fast as new catalyst vehicles today, and has absolutely nothing to do with this thread's topic of catalytic converters on Jeeps.
01-23-2011 03:54 PM
McBear On one of the Mercedes fora where I mod we had this discussion back in 2007. One of the references that I posted up then was a comprehensive comparison done by Sport Compact Car magazine in 2006 regarding different configurations and results on a DYNO.

Quote:
Originally Posted by McBear
A very good study in Sport Compact Magazine did a bunch of dyno runs on Hondas with stock exhaust systems, headers+stock exhaust, header+catback systems, headers+ NOCAT+HiProExhaust.

The results were that, of the non-header group, the HiproformanceCat +HiProExhaust was only 1PWHP less than the system that eliminated the cats completely and went straight from exhaust manifold to HiPro Exhaust system. The CatBack+HiPro Exhaust was only 3PWHP less than the no cat system.
These numbers come from dyno testing of 200-240HP Honda stock street cars with exhaust modifications as the only variable.

I am working on finding a link to the original report. SCC went out of business in 2009 so their archives are not easy to find.
01-23-2011 02:09 PM
Bubba68CS
Quote:
Originally Posted by UnlimitedLJ04 View Post
you must not follow racing much then, because the muscle car theme is alive and well. and where it is alive and well, those vehicles will flat out smoke the fastest thing ever made pre-1973 (pre-cats)...and they'll do it getting 18mpg or better. Corvette's, Cadillac CTS-V's, WRX STI's, EVO-8's, light modded Talon TSI's, SRT-4 Neon's, Buick Grand National's, chipped diesel trucks that weigh 8000+lbs...will all leave a stock 1970s muscle car in the dust no problem...and get better mileage than the muscle car, even with catalytic converters.
Quote:
Originally Posted by neverfastenough1 View Post
What is your definition of a Muscle car? A family car nowadays has more power than muscle cars of yesteryear. Look at the 350hp 6cylinder Taurus, the G8, the SRT8 Charger, the Cadillac CTS-V. Now look at the 400+hp Mustang, Comaro, GTO, and the Challenger. The V6 version of these cars still have more power than most of the Muscle cars of back then. This is not to mention, that there are 6-800 hp street cars all over nowadays. With a pulley change, you can get 500 out of a Terminator. Jeep SRT8, need I say more.

Edit: Oops, should have read to the end. I didn't see Unliminted's post.
Doesn't matter how fast something is...that just makes it a fast car.

I hate when people try to make things out to be something they are not...its like you wish you had a muscle car, so since your new car is fast you're going to call it one. Keep telling yourself that. And yes, I am absolutely a muscle car snob. Though not nearly as bad as some people I know.
01-23-2011 01:53 PM
UnlimitedLJ04
Quote:
Originally Posted by neverfastenough1 View Post
Edit: Oops, should have read to the end. I didn't see Unliminted's post.
you stated it better than me you're right...there are plenty of examples of 12 sec daily drivers out there now...right off the showroom floor, with cats.
01-23-2011 01:23 PM
neverfastenough1
Quote:
Originally Posted by Bubba68CS View Post
Muscle cars died off right about the time catalytic converters were introduced.
What is your definition of a Muscle car? A family car nowadays has more power than muscle cars of yesteryear. Look at the 350hp 6cylinder Taurus, the G8, the SRT8 Charger, the Cadillac CTS-V. Now look at the 400+hp Mustang, Comaro, GTO, and the Challenger. The V6 version of these cars still have more power than most of the Muscle cars of back then. This is not to mention, that there are 6-800 hp street cars all over nowadays. With a pulley change, you can get 500 out of a Terminator. Jeep SRT8, need I say more.

Edit: Oops, should have read to the end. I didn't see Unliminted's post.
01-23-2011 01:00 PM
UnlimitedLJ04
Quote:
Originally Posted by Bubba68CS View Post
Muscle cars died off right about the time catalytic converters were introduced.
you must not follow racing much then, because the muscle car theme is alive and well. and where it is alive and well, those vehicles will flat out smoke the fastest thing ever made pre-1973 (pre-cats)...and they'll do it getting 18mpg or better. Corvette's, Cadillac CTS-V's, WRX STI's, EVO-8's, light modded Talon TSI's, SRT-4 Neon's, Buick Grand National's, chipped diesel trucks that weigh 8000+lbs...will all leave a stock 1970s muscle car in the dust no problem...and get better mileage than the muscle car, even with catalytic converters.
01-23-2011 12:10 PM
s3nt3nc3d
Quote:
Originally Posted by doclouie View Post
If you do pull it off recycle it. I have been told there is platinum in them and they give you like $30 for each one of them you recycle or so I heard.
Yeah, they're worth some money for scrap... in fact, in some places, catalytic converter thefts are actually quite common with scrappers.

I would like to second the recommendation of a high flow cat...they're legal, they're not too expensive, they won't cause a CEL, and they'll still make your exhaust sound cooler. I put one on my old truck after my original cat started to break apart...I think I went with a Carsound/Magnaflow high flow cat.
01-23-2011 11:05 AM
n2trucking
Quote:
Originally Posted by jeeperharmon View Post
How would u gut it? And would that help with performance?
If you take it off then just run a very long rod threw it and just start hammering away until you can see threw it. If the input and output exhaust pipes don't exhactly line up in a straight line then you still can punch it but have to punch it from each side or you can cut it open then reweld it back up. the performance gains isn't all that much but your engine does not get has hot and i saw a better fuel gain and not to mention awesome sound with a good muffler. And you don't ever have to replace it again other than if it rust out but since it doesn't get has hot then it shouldn't wear out as quickly.
01-22-2011 09:50 PM
doclouie If you do pull it off recycle it. I have been told there is platinum in them and they give you like $30 for each one of them you recycle or so I heard.
01-22-2011 09:41 PM
Bubba68CS
Quote:
Originally Posted by neverfastenough1 View Post
Doing this will not adversely affect your engine performance. It will give you a bad smell at red lights, though. You can make a mil eliminator from parts at radio shack for around 5 bucks to get rid of the light. It is illegal for ON ROAD use. If there is no cel, they usually won't look to see if you have cats. I would say half of the muscle cars on the road today have done away with their cats. I put mine back on because of the smell, and I would suggest a high flow cat over elimination, but thats just me.
Muscle cars died off right about the time catalytic converters were introduced.
01-22-2011 09:36 PM
jeeperharmon
Quote:
Originally Posted by n2trucking

WHY REMOVE IT? GUT IT THEN IT LOOKS FINE!!!!!!!!!!
How would u gut it? And would that help with performance?
01-22-2011 06:57 PM
n2trucking
Quote:
Originally Posted by jeeperharmon View Post
I am about to replace my exhaust manifold ( THree Cracks). IN a 2003 2.4L, and i thought about removing the catalytic converter. is there any difference in driving with one off? any good things about removing. .and i would have it so if i got called to have inspection i could slip the pipe back on.
Pros and Cons of doing this
THanks

WHY REMOVE IT? GUT IT THEN IT LOOKS FINE!!!!!!!!!!
01-22-2011 06:16 PM
MikalCarbine
Quote:
Originally Posted by Atthehop

Are you in California. Either way the computer knows it there and may spit codes.
Nah in CT, id never do it but I was curious
01-22-2011 02:23 PM
neverfastenough1 Doing this will not adversely affect your engine performance. It will give you a bad smell at red lights, though. You can make a mil eliminator from parts at radio shack for around 5 bucks to get rid of the light. It is illegal for ON ROAD use. If there is no cel, they usually won't look to see if you have cats. I would say half of the muscle cars on the road today have done away with their cats. I put mine back on because of the smell, and I would suggest a high flow cat over elimination, but thats just me.
01-22-2011 02:04 PM
Atthehop
Quote:
Originally Posted by XtrmTJ View Post
It is Illegal to take that 'lill tag off your matress !
And your PILLOW!
01-22-2011 01:03 PM
outofmoney you will not pass inspection without it
01-22-2011 12:57 PM
XtrmTJ It is Illegal to take that 'lill tag off your matress !
01-22-2011 12:49 PM
crazyredneck on my 02 it has the 2 pre-cats (right after the manifolds) and another large one under the skid plate. the 2 pre-cats have the 02 sensors before and after them, the cat under the skid did not have a 02 sensor behind it.

The only one you could remove (not saying legally) would be the one under the skid plate because there is not an o2 sensor after it. Like it has been several times before me:

IT IS ILLEGAL TO REMOVE A CATALYTIC CONVERTOR!!!!
01-22-2011 12:42 PM
Atthehop
Quote:
Originally Posted by MikalCarbine View Post
What about Jeeps with the pre-mini cats, would removing them cause any harm or give any benefits? They are only there for California emissions IIRC
Are you in California. Either way the computer knows it there and may spit codes.
01-22-2011 11:34 AM
MikalCarbine What about Jeeps with the pre-mini cats, would removing them cause any harm or give any benefits? They are only there for California emissions IIRC
01-22-2011 11:34 AM
XtrmTJ Tastes like chicken.... mmmmmmmmmmm
01-22-2011 10:57 AM
Atthehop
Quote:
Originally Posted by bobjenkins View Post
Thought Id get some advice about keeping a stray cat out of my jeep. nope. and apparently keeping a stray cat out of my jeep is illegal! WHAT!?!?
Bring the stray cat to the local chinese restaurant. They specialize in them.
01-22-2011 10:53 AM
doclouie I know running without a CAT is like a $2500 fine or so I was told at the shop.
01-22-2011 10:11 AM
trailtwister I also removed my cat on 97 4.0L with no problems. Just remove CEL bulb.
01-22-2011 09:08 AM
XtrmTJ
Quote:
Originally Posted by UnlimitedLJ04 View Post
you'll find only bad things about removing the cat.

engine will run like crap cause the computer will freak out and throw CEL's. and removing the cat is illegal.

I have had mine removed from a '97 4.0L for over ten (10) years now with NO problems at all ! Even past smog check last month !
01-22-2011 02:32 AM
TJ-Q8 But i looked under my 01 and i dont seem to see any sensors like on other cars that are aftr the cat. Doesnt that mean it wont read codes?
01-22-2011 01:16 AM
s3nt3nc3d They make a thing called an O2 sim for the O2 sensor that is affected when the cat is removed...that basically tricks the computer into thinking the O2 sensor is functioning correctly, however, as mentioned...it's illegal to run with no cat on the streets.

I don't think you'll see any power increases really...but I've heard it does deepen the exhaust tone considerably.
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