Opinions on cutting out catalytic converters.

[AyWoSch Motors]

What's everyone's opinion on cutting out catalytic converters? I've mentioned it to a few people, some say "get rid of those stupid things, they do nothing", other people say "dont touch them, if you cut them out, you'll blow up your engine", and everything in between.
I have 2 trucks in question that I'd like to get rid of them on, a 92 suburban, with a giant one, and a 97 3500 with 2 little ones. I figured before I do anything crazy, I'd ask and see if doing so would affect anything.
I'm thinking along the lines of, less back pressure, less weight, a little louder, but mainly from the stand point of, they're worth good money. And one less part and a bit of extra money is always a good thing, right?
My 94 yukon blew one up, scattered all the guts onto the street one day. I just put a piece of metal back in where that was. Ever since then, it's never had any issues. In fact, it seems to me to be running alot better.
And I've known a bunch of people that just cut them out, and havent had any issues, but I've also had some people tell me some horror stories.

Opinions??

 

[Ellie Niner]

The 1997 is OBD2, so will have an oxygen sensor after one or both converters. If you ace the converter on that application, you'll end up with a check engine light illuminated all the time., and it may not run optimally. The 1992 will never know the difference.

My personal take isn't the most popular one, but I do my best to keep an engine running well while maintaining the emissions equipment it came with. If you are gonna remove emissions stuff, taking a sawzall and a gas axe to it without figuring out what exactly you're doing, can leave you with less power and poorer drivability than you started with. Planning it out and doing it properly may or may not net you any performance benefits. When the original converter on my 1986 rotted out and shat all the catalyst beads out the tailpipe, it made zero difference in power. I was on the fence, thinking about replacing it (and the rest of the exhaust) with duals, but my whiny girlfriend complained that it smelled gassy and made her clothes stink and wahhhh, so forced my hand a little. I ended up with dual exhaust and dual cats, and am pretty happy with the results. Didn't gain (or lose) any power, and I'm at least making an attempt to keep things clean. So yeah... I'd probably delete a muffler before a catalyst.

 

[77 K20]

They are good for starting brush fires. And since the whole world is in a drought and on fire there is that to consider.

That being said I had a shop replace them with a straight pipe. Had to pay cash. Don't think they will do that anymore.

There are aftermarket ones that flow well- and it costs more than a "test pipe". Kinda depends on what you are using your vehicle for.

 

[Salty Crusty]

They don't hurt engine performance one bit and actually make exhaust cleaner. Leave it alone.
I'm not a tree hugger, but since they actually perform a function and do not cost power, why not?
The "screw the environment" group is just as obnoxious and misdirected as the "save the environment at all costs!" group.
If you have vehicle inspections and they catch it without the cat, you'll be out the fine plus you'll have to buy new ones and pay to have 'em installed.

 

[drware]

My 1986 K30 came without them. Had two smog pumps and dual exhaust from the dealer.

 

[Vbb199]

None of my vehicles except my wifes car and my grandma car have catalytic converters, and havent, for years, they run fine, and make plenty of power as they should.
I'm not saying go take your sawzall to everythinf you own, im saying, as they failed, or clogged, i'd just cut them off and run a straight thru pipe to replace them.


On some of the newer stuff, i know they might be needed, in terms of back pressure.

My buds that run LS motors had learned once they removed the cats, there was insufficient backpressure afterwards, and the post cat o2's acted up.

But i dont, and wont, own such things, so it doesnt concern me,

 

[dvdswan]

If you just park the truck in a meth neighborhood, the cat will be gone in under an hour. No labor involved.

 

[Matt69olds]

The older big catalytic converters didn’t flow very well, but the engines they were connected to didn’t make much power either. If the engine doesn’t breath well, the converter isn’t much of a hindrance.

The newer converters work pretty well, they breath much better than the old pellet style. But as someone mentioned, OBD2 has 2 oxygen sensors, the second monitors the converter efficiency. It obviously won’t do anything if it’s not there. They do make O2 sensor simulators to trick the computer into thinking it’s still functional.

If it ain’t broke, don’t fix it. Unless you have a modified engine, you won’t gain any performance removing it. If the engine is modified, either remove it and add the simulators, run 2 converters and dual exhaust, or you could delete the converter and have the PCM reflashed to ignore the second o2 sensor. Depends on how much you want to spend, and how much you want to help the air.

 

[Goldie Driver]

I am not a fan, but ...

I agree the later models dont rob power like the old ones. The Camaro still has them.

Goldie does not, but that is the way I got her.

Now, the older - say 75 thru perhaps 80 - converters from GM had a giant hex plug that *ahem* allowed the catalyst pellets to be replaced.

If Goldie still had her cat, I would probably drain it to reduce back pressure.

However, I would probably discover how much oil she burned that was hidden by the cat ... as I am aware of being that she is catless.

So, at this point, I'd recommend the lazy route - leave it as is - and accept that on the 92 you will probably not see a difference, and on the 97 you would probably cause more pain than gain.

As a bonus, you are still "legal" if that is an issue.

YMMV, see your dealer for details.

 

[eskimomann209]

I didn’t read all the responses but am happy to add mine.
You can delete them, and there are dummy rear o2 sensors that’ll keep the CEL from tripping.
Sometimes they don’t trip and all.
Leaving them unplugged sometimes works too. Or you can have em tuned out ALOT of ways to delete em.

That being said my 73 didn’t have em, and I wasn’t adding em when I LS swapped. You get that fuel smell from the exhaust without em. But I like it. Adds a little nostalgia to me.
Owners choice IMO

 

[AyWoSch Motors]

Well, I wasn't really worried about them being clogged or anything, but I'm the type of guy that likes to simplify stuff. One less component in the system would make me happy. And a buddy of mine just brought his cat in to the junkyard, and got like 200$ for a little tiny thing. Thought I some extra money wouldn't be a bad thing.
The 97 runs great, and I hadn't really thought of cutting them out, but I blew a head gasket in that truck a while back, and I believe that it blew a bunch of milkshake sludge into the exhaust, because everytime I start it up, after a few minutes, it has this terrible burnt sludge sorta smell. I planned on cutting the exhaust off, and try to clean the pipes or something. And then I thought it might be in the cats, that's why I thought about cutting those off.
On my 92 Burb, its runs okay enough, but it has no balls. And it has the same exact drivetrain and about the same milage and years as my 94 yukon, but the 94 runs awesome. The only thing thats different really, is the Yukon doesn't have the cat and the Burb does.
Thought maybe it might be all clogged up, and it might run better with less back pressure. But that could be anything, I was just thinking.

 

[Vbb199]

Cats are worth the cash if you find the right guy... and i dont mean no yayhoo on fb marketplace buying them. I cashed out 6 of them i had, and scored 700$

 

[AuroraGirl]

as long as they are working right I wouldnt be too upset because a lot of our bigger trucks conveniently hit certain gvw or fleet percentages by certain years not requiring some lol.
howeveer if it IS THERE then I would make sure if its needing an AIR Pump to work right you dont dilly dally on that. because if you want to cause one to fail early and deal wit hthe headache + the labor to replace with either pipe oir another... at that time likely had decreasing performance for a while... etc...


My dad just got a great deal on the companys 2001 F350 with the V10. (oh.) but its a heavy duty light duty truck and its not 2005 or newer so its not required to have OBD2 compliance and in this case it has 2 oxygen sensors for the manifolds but the cat has none and its LARGE. I told him, you dont cut that off unless it gets bad because I feel you might just get gas-ed out with gas fumes if you dont.

 

[mikeoverland]

Does the 81 C10 even have a Cat? I ask since there is no cat on the truck, no place where one was and no O2 sensor. The vehicle DOES (kind of) have an EGR valve........

 

[Goldie Driver]

Does the 81 C10 even have a Cat? I ask since there is no cat on the truck, no place where one was and no O2 sensor. The vehicle DOES (kind of) have an EGR valve........

81 as far as I know would have come with a cat, even Federal Emissions.

Goldie is an 80 and came with one.