My Catalytic converter is bad so I am going to hollow it out until inspection time comes around in a year and a half or so. What is the Outer Diameter size of a pipe that will fit inside the Catalytic converter? What I am asking is what is the Inner Diameter size of the Catalytic converter so I can put a pipe inside cat.

My car is an 89 Iroc 350

 

you could just pound the guts out and leave it as is but it should be slightly smaller then 3 in.

3 in outer diameter cat = ? inner diameter.

 

just measure your y-pipe, the cat's "neck" was a slip fit over the y-pipe, there for the same size pipe should fit on the inside, of course I'm guessing about true fit (rust and stuff), I ended up cuttin mine off and up a pipe in instead

 

I would just pull all the ceramic and what not out the cat and leave it hollow with no pipe. Will be the easiest thing to do until you can get a new one.

 

Well this may be a dumb question.... but i have a 85 z28, what would i have to do to gut my cat since it also is going bad? If it's simply pulling out stuff, i've heard that the stuff inside is toxic, what should i do to take it out or keep from harming myself haha. Im just a kid trying to learn amap sso any help would be aprreciated

 

I wouldn't worry about it too much I did mine about a year ago, I have a foot long drill bit, and some smashing goodies (pry bars, etc) after you mash and mash you I started the car up or sometimes used a shop vac to blow/suck the honey comb out.

as long as you don't eat the crap you'll be fine, I'll still alive, no side effects , but I'm still 19

 

Don't worry it's not toxic. It's not like abestos or something. Just get some good prying tools and mash the comb real good then try a coat hanger or something and pull it all out. Just don't eat what comes out and wash your hands when you are done

 

So if I am about to purchase a new high flo cat should I gut it also to get that throaty sound or not? Will gutting the high flo allow me to pass the Illinois Emmisions test?

What cat should I buy? I have a LG4 4bbl Quadrojet with a Flowmaster 80 series.

 

There would be no point in getting a hi-flo if you are going to gut it. Just gut your stock one and save money. But gutting a cat will make it fail smog. Yes a hi-flo gives you a nice throaty sound. I know mine made me louder

 

Just so you will know, a gutted cat will give your car a crappy tinny sound, I know because I had one for a short time, then I had a buddy at a muffler shop weld in a straight pipe to replace the gutted cat, you would not believe how much better it sounds with a straight pipe there!!!

 

I had my straight pipes made yesterday, if you're going to gut it, put a pipe in it. It sounds *much* better.

 

you can get a replacement cat at Napa for about $100.00

 

Angle grind a rectangle section out of the bottom of the cat box, drop all the crap out, and weld the section back in. (You can leave the cat sensor tube thingy as is). I cut off the rear baffle box, and had a straight single pipe exit from the centre rear.

Sounds good to me. (And not at all *******!)

I can e-mail the sound file.

 

Im going to try to put a straight pipe through the middle of my cat. It hollowed itself out on its own. We dont have emissions tests in Florida.

 

anyone ever have straight pipe rigged up at a muffler shop? with the flanges and all? if so how much, if not...estimate? thanks

 

thats what we did, my buddies dad cut the flanges off my cat and welded it to my pipe. completely bolt in. made the 'ol LG4 sound a good bit more throaty, more defined. wished i coulda put some headers on that thing...