nimrod_sixty9

Should I get rid of my catalytic converter? What will happen?

It leaks directly behind it anyway - so I figured I'd take it out.

305 TBI

MKnight

What will happen is you will gain some HP

Crusin' 1980's

Many people would suggest replacing it with an aftermarket Hi-Flow catalytic converter so your emmissions will be in check. Removing it will make your exhaust noticably louder and will smell more when the car is running.

urbanhunter44

iTrader: (3)

Pros:

- It's gonna sound better
- It's gonna smell better
- Possible 2 rwhp gain if you pipe it
- If you don't gut it, you can reinstall it for emissions easily


Cons:

- You gotta spend an hour doing it
- Might cost between $0 and $30 depending on how you do it (gut it or run a pipe..)
- You'll need a new one for emissions if you gut that one

Would I do it? Oh hell yes. Have I done it? My '94 was uncatted, and my '97 will be in two days

firebirdjosh

iTrader: (1)

I disagree with both. Sounds and smells like white trash, and it pollutes unnecessarily.

Cruz'N Bruz'R

Dude, we drive Thirdgens, we ARE white trash.

nimrod_sixty9

Thanks guys!!!

Bye Bye Cat! Lucky for me there are no emission checks in Florida. So no worries for me .


2HP for one hour of work...... SWEET!

Like I said the thing leaks anyway. My muffler already fell off. And I do plan to put a striaght pipe in its place. Since my muff is gone, the exhuast stops right past the axle, will this cause a prob or pro? I can still put the muff back on with an elbow pipe. What should I do?

nimrod_sixty9

Hey the guy behind me has to smell it, not me . As for polution, we shouldn't even drive these things at all, and the thing leaks anyway.

firebirdjosh

iTrader: (1)

So if you're going to pollute might as well really go for gusto? Sounds reasonable . Also, you said the leak was after the cat so how is that relevant? Obviously it's your car and you can do whatever you want and everyone has their opinions and all that BS.

nimrod_sixty9

Well doesnt the Muff stop some of it???

ShiftyCapone

iTrader: (7)

The muffler has an effect on sound pollutants and not chemical.

If your leak is aft of the cat I would fix the leak. The cat has nothing to do with it. Gutting the stock cat on an LO3 will yeild you negligable power increase all the while polluting more and making the guy behind you switch lanes. A cat-less LO3 has a less than desireable sound as well.

nimrod_sixty9

I dont know about the sound thing. Cuz my 89 had nothing but pipes and it sounded like a beast . And of course pissing off the cops .

IROCThe5.7L

For some reason, this made me LOL.









Ok sorry, back on topic.

nimrod_sixty9

LOL... Point taken.... Went from Catalytic Converters to white trash

Can anyone answer my Q's?

urbanhunter44

iTrader: (3)

I like the smell of an uncatted V8.. .... .....

Quite honestly, him catting or uncatting his engine really isn't going to do much to affect pollution.

nimrod_sixty9

So no muff or cat... or should I put the muff back on???

Nate86

Dude, honestly... if your catalytic convertor is working properly then just leave it alone. Just fix the leak and be done with it. I would recommend a muffler as well but I know a lot of people like that "loud" (i.e. obnoxious) straight pipe sound.

Cons to not running a cat:
1. Pollution
2. Smell (debatable; I personally can't tell the difference)
3. Negligible horsepower increase without other supporting mods
4. Exhaust tone will be quite a bit louder and more raspy
5. I don't know why but thirdgen f-bodies have a common problem with the exhaust "popping" when you rev it without a catalytic convertor. To me, this seems very "white trash" and I can't deal with it at all. It's basically a sound so bad that even people who don't know a lot about cars are left scratching their heads trying to figure out what's wrong with your car to be making that horrible sound.










Ok... maybe I'm exagerating just a bit but it does sound crappy when it makes that popping noise. That's what sealed the deal for me on a high flow catalytic convertor.

nimrod_sixty9

Well what if I took the cat off and put the muff on? Would that get me outta trailer park status?


I really don't think it is working properly - I tap it and it sounds like its full of rocks. I feel I am loosing HP and I can't find out where Im loosing it at... After 3K RPM it seems to completly lose it, at least in my opinion. It looks like its the stock one and my car has 217,xxx miles on it!!! So what do you think?

BTW: Im on a student budget (poor). This is why im trying to talk myself into it (if it has a problem), instead of buying a high flow cat. Truely sorry, I dont mean to pollute, but I think Im screwed anyway.

92rs85berlintta

iTrader: (1)

If you remove it your clothing will smell of unburnt gas anytime you drive it. Your eyes will water if you stand behind it and god forbid what happens when you idle it through a drive through window. Do the world a huge favor by at least putting a high flow cat on there. Most of the time you can actually get worse HP by removing it or gutting it because it creates turbulance in your exhaust. With your engine you will not likely notice any difference. Trust me I know from a past expierience(mistake) I fell for the myth of noticable hp gains and ended up spending more $$ to get a new cat.

nimrod_sixty9

Thanks for the INFO


Ok I hear ya. I didn't have the smell prob with my 89'. Anyway Im not looking to get HP, Im looking to get the HP back that my cat has taken (if it has taken)..

So ppl don't tell me if I should or should not do it. Tell me if you think its broke or bad... If its not then Ill do nothing... Don't need to do anything if nothing will change...


IF NOT...



Then what do you ppl think my problem is??? Oil, tranny, plugs and wires, cap rotor, all good! I use more gas in 3 miles of city than I do in 30 miles of hwy!?! Serious!! Anything past 3K RPM seems to suk... If anyone knows about this, let me know please!

Greg '85 T/A

I have an interesting contribution to make here. A friend of mine was in a fraternity at what was once GMI (General Motors Institute). A few years after college, he had a reunion party, at which I was a guest. One of the frat brothers had, at that time, become an engineer at GM. He worked on the software in the Firebird/Camaro ECMs. I had just bought my T/A, and, after admonishing him for not putting 350s in the cars (like it was his call), asked him what I could do to increase power. He said, "remove the cat."

Personally, I don't care if someone removes it, as long as the AIR/EGR system is functioning. Lawnmowers pollute the air much more than de-catted thirdgens. A lot of cars will still pass the sniffer w/o a cat.

Of course, it is against the law . . .

ino

dont have a cat here?

nimrod_sixty9

No its still on- I can't find my muff.. LOL..

Greg

redliterunner

You guys really should spend some time in countries and cities outside the US where cats are not required. e.g. Bogota, Seoul. A couple of days there and, I promise, you'll gladly pay money to fix that converter and keep all your smog stuff in good working condition.

The naked truth is that your not going to feel any noticable increase in power, and your not going to outrun anyone you can't outrun already by getting the converter off. It'll just be a bit louder, and will discharge about a hundred times more NOx. Actually, keeping the converter and ditching the muffler gets you a better sound.

I'll bet that most of the 50 fastest street cars on this site still have converters.

nimrod_sixty9

Disagree on the sound - because that is my cars current set up.

Also im not looking to get HP, I just can't think of anything else that would make my car run like crap,,, you see? I just want the HP back that is aleady taken from me,,, which I think my cat is bad or soon will be!

ND4SPD86

iTrader: (1)

Neither one of my third gens have cats and my eyes don't water when I stand behind them and are not loud at all they both sound as if they have full exhaust system.

89BlueRSCamaro

I took off the muffler from my 305 and it sounds nice...all i have is two cats, a 2 1/2 inch y to 3 inch pipe to 2 1/2 inch y out the back...sounds really nice...not loud at all and good performance.....and smells nice.....if it smells bad and pollutes then you have a engine problem......

heavychevy

ive gutted the cat on my truck and i can tell the exhaust note is a little deeper, but other than that, i havent noticed any differences

LT1FUN

If you gut the cat, or remove it all together, you'd probably pick up a few horses, only because the cat you've got on their now, is probably old and doesn't flow very well. You'd be much better off with an aftermarket high-flow 3" cat instead. If anything, you'd probably gain MORE hp (and definetely torque) then not having a cat at all.

Unless you're going for 450+ HP, a high flow cat, won't cost you any power at all.


If you do end up gutting the cat or adding a test-pipe, one thing you should keep in mind, is that the exhaust will be quite a bit louder, which may (or may not) become annoying to you in time, especially if you drive a lot on the highway. Even worse, you'll add a lot of raspiness to the exhaust note aswell. A lot of poping and farting on de-aceleration, or whenever you rev the motor. It sounds aweful. I see guy's all the time with Flowmasters and what not, reving their motors, and you can always tell if the cat's been removed because the raspiness is all over the place. There's no definition to the exhaust note. It's "all over the place". Just loud and annoying. Quite frankly, it's as annoying as having someone run their nails across a chalk board. I can't stand it. If you had a built motor on the other hand, that'd be different, but on a bolt-on car, getting rid of the cat makes your exhaust sound very annoying.

Whenever you pull up to a stop light, the smell of the exhaust will now flow into your car and stink everything up. After a while, you'll think it's disapeared, but it hasn't. The stink is still there, it's just that you've gotton used to it. Your passengers on the other hand, will always smell it but probably won't tell you they think your car stinks because they don't want to hurt your feeling.

Also,

Depending on where you live and emissions laws in effect, removing the cat can be worth a huge fine as it's (obviously) the most important part of your emissions system.


My advice, buy a high flow cat. You'll get more HP/Torque. You won't have any of the raspiness or popping/farting that goes with not having a cat, the cops won't hassle you for it, and your car won't stink.

Oh and you'll be doing your part to save the air we all breath.

Don 79 TA

i have a gutted cat off her 88 formula if you want
it's for the larger exhaust, i think the 305tbi was smaller piping

also
look on ebay for the test pipe kit
i bought one for the 97 jeep and her 88 formula
works great

Cruz'N Bruz'R

Your telling me all you smell is gas when you ride in pre 75 cars? Come on, get real, now your just stretching it. If you have a proper tune you shouldn't smell anything. i had been behind my car many times while running, and it doesn't smell of anything, even after I pull it out, and start it up in the spring.

Crusin' 1980's

a car probably will smell bad without the cat...my camaro had a good tune but made my eyes water whe i took the cat off, and it stunk

Cruz'N Bruz'R

Then your TUNE had to have been off. Both of our cars(were) are catless, one, a 70 monte with 383, the other 87 iroc 383, both run with no smell whatsoever. And the Monte runs pig rich.

92rs85berlintta

iTrader: (1)

Well everyone keeps saying it doesnt pollute and doesnt smell without one if its running right. Thats 100% untrue even more so since its 305 tbi. WIthout the cat there to reburn unburnt fuel and take the nox out of it, it is going to contain more fuel vapors and smell worse and pollute...thats a fact. He already stated its not running correct so removing the cat is only adding more issue's. I say just get a high flow there pretty cheap and you will have good sound, pic up the lost hp, no smell, low pollutants and best of all its legal. It doesnt matter what state you live in its illegal to take it off. Then you can trouble shoot the 3000k wall you are seeing wich is most likely cause by tbi issue.

From the sounds of it you already know what you were going to do before you posted the title Which only sparked a debate.

kinda contradicting.

Crusin' 1980's

Or what you could do is get a high flow aftermanrket cat and put it on (since you'll need it to pass inspection), and then if you absolutely don't like it (i don't see why you wouldn't like it) then you could consider removing it. But that might be an option before you simply remove the old one.

92rs85berlintta

iTrader: (1)

Theres no inspection at all YET in fla so hes ok for a little while there but after i took my cat off and learned from my mistake i will never do it again. Its like changing your oil in your lawn and letting it drain in the grass. Just somthing you dont do unless you want to pay for it later.

TransAM Joe

iTrader: (6)

If you want to keep the cat but gut it you should weld a length of pipe through the converter, same as a test pipe with a cat shell around it but looks like you have a full functioning converter(have to pass MO inspection). My 355 TPI has this with 2055 Hooker shorties, 3" Flowmaster American Thunder Exhaust and is not raspy at all, very deep and aggressive/loud. If you just gut the cat without putting a straight pipe through it, the exhaust flows from the y pipe into a bottle so to speak and then back into the intermediate pipe creating a vortex of turbulence in the gutted cat giving that undesirable raspy sound.

nimrod_sixty9

WOW! I hope Im not gonna get shot over this!

Sorry for the contradiction. I did decide before posting - I just wanted to back myself up. Since I didn't, the option is still in the air. So since I have seen the same pros and cons posted over and over - I wanted to know if it was my cat causing the prob in the first place (which is making me decide). Didn't mean to sound like an ***, guess I desrerve a >

As for the posts go- I dont think Ive seen opinions more split since the Gore - Bush election!

Thanks ppl!
----------
BTW: Im definatly not gutting it. I would put a pipe in its place and put the muff back on.. If I can find it

Nate86

I think quite a few people have given you a good solution: Replace the tired factory cat with a high flow model. There's no real disadvantages to this, except maybe being out $120 or so. To me, this seems like a negligible problem since some entire exhaust systems can cost well over $1000.

So let's review:

Pros

Less smog pollution
Less noise pollution
Possible HP increase over factory catalytic convertor
Reduced/eliminated raspy-ness of exhaust tone
Reduced/eliminated "popping" noise when decelerating or revving

Cons

Costs $90-$150
May not fit factory exhaust

My opinion on what to do is pretty clear. I don't have a problem with people that don't run a cat--that's their personal decision. However, common sense will tell you that if we don't act responsible about pollution today (which already happens to be a pretty bad problem in some cities), it's going to affect our lives later on down the line. When it really comes down to it, there's no really good reason NOT to use a catalytic convertor with your exhaust system unless you're just cheap or lazy (not pointing fingers at anyone, just my own personal opinion).

WckdDudeMan

Just wait till a cop gets a bee in his ***... hell look under it and unless you gutted it GOOD(either run pipe through the inside of it or gutted it and put it back how it originally looked) thats a 2k$ fine in florida... spend the 50 bucks and get a highflow...

oh yea and at any time they can do a vis inspection in florida... dont need to be doing anything for them to choose to do it.

Nate86

Sounds like to me. I've lived in Florida my whole life and I've never heard of anything like that. No one that I know has ever even mentioned anything about visual inspections in Florida, nor do I know anyone who has ever been pulled over and asked about the exhaust at all, much less a catalytic convertor. I'm not sure where you live but my local police don't enforce exhaust rules at all... I constantly hear trucks and cars with straight pipes on the street, even some with no pipes at all. Just headers. In fact, I ran an open exhaust for about year until I couldn't take the drone any longer and put on an exhaust. Never once got pulled over for exhaust reasons, and I drive my car daily.

I agree with you about spending the money on a cat, but no need to make up stories to scare people.

nimrod_sixty9

Agree with Nate, thats . I have also ran open headers, but I did get pulled over by a state! He gave me a warning for it being to loud !

I do not have the money to buy a cat! So it stays or goes! But if it goes - I like the pipe though cat idea.

WckdDudeMan

The muffler shop I went to to get a muffler I picked out of the junkyard had it posted.(well not the visspec part). Ive seen 2 shops with it posted... the third i went to to get a quote was welding straight pipe into a 95 mustang as I waited on the counter guy(exhaust only shop, not midas crap) lets just say thats not where I went back to.

if you feel like reading this it says any emissions tampering makes it illegal for the car to change owners.
http://www.epa.gov/region4/air/sips/...ter-62-243.pdf

As for visspec, I know that cause I helped a friend do custom lights, he got pulled over, they looked at it, no DOT, he got off with warning rather than 85(i think it would have been the same as driving with non working taillights and stuff)$ ticket.

http://cgi.ebay.com/ebaymotors/3-3-0...55903796QQrdZ1
theres a magnaflow cat 3" for 60 theres others if you look i did it fast.

Not sure on these engines but I know on the 3.1s and 2.8s you burn hella lot more in gas if you run without a cat(car runs rich). However it may be different depending how the computers operate in these cars.

Then again your over by okeechobee so it doesnt really matter to you about the visspec(nonmetropolitan area they would be less likely to care) , but I do think you should get one.... or at the least cut your cat out cut it open, gut it, weld pipe in its place and weld the gutted cat over it.

superGMman

I think that there is no excuse to take out a cat unless it poses problems like: Cost, fitment problems, isn't working, or is stuffed with concrete or animal parts.

I can understand when someone is installing a full exhaust system and they cannot afford a new cat, but it doesn't make any sense to take remove a cat on a stock RS. It'll probably smell and sound like Rosie O' Donnel's asscrack

Crusin' 1980's

i think it will smell more w/o the cat

urbanhunter44

iTrader: (3)

I bet three quarters of the people who posted in this thread have no first hand experience with actually removing a cat.

It won't make it sound like ****, it won't make it smell horrible and choke you to death and it definitely will have nothing to do with Rosie's *** crack.

If your cat is messed up, just pipe the thing and save some dough. Then buy a cheap highflow for inspections whenever they come around next.

92rs85berlintta

iTrader: (1)

Do people read the thread anymore before posting?? Nothing personal but it makes yourself sound kinda dumb. I have first hand expierience. anyone come to my house i will show you what a car with no cat smells like that is properly tunned by mad -z and runs great ill show you how everthing said above is correct. Then we can go over to my neighbors drag out his mint chevelle with no cat and check that... then 3 doors down we can hit my neighbor who has a vw bug. Hell my idiot brothers 95 s10(florida). all have no cats run good and all of which all of the above mentioned issues are true. Its a fact not peoples opinions.(except the rosies *** thing unless were talking about the smell). Luckily my car doesnt get driven with no cats its just in the middle of and exhaust transition and paint job.

Apparently they make cats for looks because if they dont do anything then companys must waste billions every year making them.

superGMman

haha yeah the Rosie thing was stupid. Maybe my and others experience of smelly, horrible sounding experiences from the removal of cats is the result of a car not running right. That is the only reason I could thing of. Make sure your car is running right.

urbanhunter44

iTrader: (3)

The smell will change slightly.. but it's not a horrible smell of death. It smells like the drag strip actually, or maybe like a car show with a bunch of old cars with hot big blocks. And it won't kill you inside your car

WckdDudeMan

if you tune it right, not all that many people tune these engines right when they make that change... thats why you pull up behind 80s caprice with no cat or a clogged cat and it smells like wrotten eggs... oxygen sensor is picking up a bad reading or out of service engine starts running rich... bad smells happen