I'm thinking about gutting my catalytic converter. I know it has been done a bunch of times before. I have two big questions about it:

1) Is there a writeup somewhere, so that I don't do it wrong and end up having to buy a brand new one?

2) Would this cause the car to fail an emissions test? I'm moving up to GA in a year or 2 and I would much prefer NOT to have to go through and replace parts, because I was stupid the first time around.

Thanx in advance!

~Derek

 

Youlll fail the test if they have a sniffer in your pipe with a gutted cat. Id either put a hi flo unit in(they are cheap) or cut the cat out and weld a straight pipe in its place. Even without the guts you get some turbulence due to the shape of the cats shell.
IMO not worth the headache for the 3, maybe 5hp increase, youll never feel it.

 

mine was gutted, now it rattles to hell. I have my entire exhaust off and im gunna make duals out of it and eliminate the cat alltogether

 

I gutted the cat on my car and now the car is way too loud and sounds like an old truck. I have muffler eliminaters that I'm about to replace with some borlas. The car smells a little too. If I could do it over, I would leave it as is and not gut the cat. Just my opinion though.

 

Thanx =)

I've been thinking about getting a Catco High-Flow. ($105 from racepages.com)



Would that fit stock? Also, would I expect any sort of performance gain from it?

 

When my car was still basically stock I passed a dyno emissions test in Pa with no cats, you kust have to tune it right and test the car first thing in the morning, basiclly when its cooler it wont produce as much NOx. But even I am going to put on high flow cats because the car is too loud.

 

Wouldn't that fail a visual in some states?

~Derek

 

You need Longtube headers to see a major difference. Might be a problem if you need to pass emissions eventually.

 

If you have the L98 it has two front converters and a reasonator. Remove the front two and run straight pipe and put a high free flow cat in place of the reasonator. There are test that show up to a 15 hp gain. Dont no if its but just passing it on

 

I thought that the warmer an engine the lower the emissions numbers?

 

On the L98 I believe the front two are precats (worthless IMO but needed for smog) on the front "Y", and go into one main cat. The previous owner of mine gutted the precats, and with a completely stock system resonated worse than the aftermarket sys. I have now.

 

The HydroCarbons are lower at a higher temp because fuel atomizes better in a warmer engine and as the cat(if you have one) heats up it works more efficently. But without a cat your best bet is a cold run if you have NOx problems(most catless cars do), at least thats my understanding of it all. I tested warm and failed, left the car overnight on the dyno, started it next morning and ran it......it passed.

 

that's most odd. NOx is a result of heat, and cats do nothing to control NOx. That's what EGR is all about.

I am not a fan of gutting cats... if for only one reason: if we, as hobbiest and enthusiasts continue to act like its 1966, we will loose everything. the EPA will mandate that every state follow CARB like enforcement. In short, we will be ****ed.

The other side of the equation, states like CA and NY are initializing road side test systems. These will use infared sensors to tag gross polluters. As far as I know, if your car stinks, it will get a notice, no matter where it is tagged. You may not get a fine, but you could get a nasty gram. But don't be surprised if you get a fine. These will start to popup in major urban areas over the next 20 years, I suspect.

The L98 has a most restrictive exhaust system. The best way to liberate power is to remove the entire exhaust system and add a true dual system with high flow cats, located about where the pre-cats sit and an x-pipe. this will keep cabin noise down to tolerable levels and I promise it will pass ANY sniff test.

However, it will fail a visual inspection in an instant. The upside, is that only CA and several northeastern states are requiring visual inspection.

Finally, before we start to collectively hate on big brother, I laud the effects of the EPA re: auto emissions. Do you really think that we would have clean 500+hp engines that can get 26mpg highway on their own? No, I don't.

 

Derek
What are you trying to accomplish? I don't mean "Why, I want to gut the cat you dope".... I mean WHAT are you trying to accomplish by gutting the cat?

Your car is an older one and therefore depending on your state, they're going to shove a probe up the pipe to test the emmisions just like on my 95 and I do not believe that you will be able to pass emissions with a gutted cat.

 

You said it Bogus! Go for a high flow cat. Big brother is inspecting those cats in more and more states.

 

On my old stock L98 with Hi Flow cat , replacing it with the 3" pipe I use at the strip gave .15 better ET back to back everytime.
However as stated above had to install muffflers instead of eliminators because of extra. noise

 

Polk county, FL quit the emissions testing a long time ago because the EPA wasn't making enough money off it. Dunno about the EPA but Federal law seems to override everything. But states like FL give those decisions to the individual counties themselves. I wanted to get a brand new cat but the muffler shop wanted to charge me $700 for an OEM one from GM. Heck no was I gonna spend that money!!! So I decided to just weld up a nice Dynomax bullet muffler in place of the main cat for $30. With free mufflers I could have never been happier but still my exhaust stinks.

 

you don't understand how the EPA works... it has nothing to do with the "EPA making money."

What happens is this: An area has high ozone readings. This is caused by a lot of traffic and climate conditions. The EPA gets a hard on and tells the state that something must be done about the polution. Depending, it could mean that the region is required to test emissions.

For example, FL will not see EPA testing anytime soon thanks to the nature of the tradewinds... all the crap gets sent out to sea, one way or the other.

I used to live in Delaware, and Northern Delaware was under different emissions testing requirements than Central and Lower Delaware. All because of population and the transferance of pollution from the big urban centers (Philly, Baltimore, etc).

The bottom line is this: In many parts of the country, EPA requirements are unenforced mandates. It is still illegal to modify the emissions of your car, regardless of where you live, but it does make it less likely you will get caught.

My fear is that the EPA will one day come down on us... and all the loopholes will be sucked away.

As for a cat for your Vette, you can get high-flow cats for about $100.00 that will remove the stink and be quieter than the muffler.

 

there are good reasons for everything....

 

with Bogus and others regarding the EPA. But, to answer your question, you just remove the cat and take a hammer, a pipe and beat
the heck out of the honey comb inside the cat until it's all out. I gutted a cat when I lived in Kalifornia, at the time thay had road side tests and used the sniffer-I never failed an emissions test! I also believe polution has more to do with an unmaintained (car seldomly tuned) poor running car even with cat(s).