I have seen “gutting the cat” mentioned a few times here on this site so I looked into it to see what was up. Is there any reason (better or worse) to gut the catalytic converter over just getting a cat delete pipe? And I noticed that on sites where they sell a cat delete pipe they say “for off-road use only” – what’s the deal there? Is it illegal to remove the cat? So wouldn’t it be a better idea to keep the old cat in case you needed to replace it? Or do you want to leave it gutted, in place, so it looks like it is still there? I’ve also read that there is no need for a catalytic converter on a PSD – true?

 

There is no cat on your truck, it is a soot convertor. A diesel does not produce the gases which a gasloine motor does, and the cat does not do anygood on a diesel because the gases are not there in the first place. I would gut it out and put it back on there, so if a state patrol looks under your truck it looks like its there.

 

In addition to what 78fordman said, some of the trucks don't even come with cats. The automatics don't have them, but the manuals do. Why this is, I haven't a clue. I'm removing mine in the next couple weeks and putting a 4" turbo back straight pipe.

Terry

 

Actually,

The Catylitic converter does work, and yes there are "gasses" coming out of your tailpipe, otherwise you wouldn't need an exhaust pipe. The purpose of the catylitic converter is to process unburned /partially burned hydrocarbons into more benign products. In a sense it is a "soot converter" but not quite. It gets some of the unburned or partially burned fuel, but not all, thats why you can get black smoke when you romp on it. They need heat to work properly, and once up to temp they get really hot when they are processing the exhaust gas that has something to burn off. A catylist is a material to enhance chemical reactions by lowering the energy required for a reaction or facillitating of a chemical reaction. And yes it is illegal to remove a cat from a vehicle that was manufactured with one per EPA rules. But that won't stop me or anyone else from taking it off. I agree they don't do much, but in the big picture, every bit helps air quality. I'd take it off and save it when you sell it. Some states won't allow you to sell the vehicle without it, it will not pass a physical inspection. I had a hard time convincing my state exhaust testing agency that my 78 bronco did not come with a cat, and therefore had a hard time getting licensed.

 

you dont need it, i deleted my cat and i love it and wont ever go back! gutting the cat is just a wimps way of wanting to be an outlaw, i think that if your gonna do it you might as well go for the gold! ford didnt have cats on their 99.5 to 2003 7.3 psd trucks so why should we? nobody will know that your cat is gone unless you get pulled over for a sound violation which to me is nearly impossible in a diesel pickup cause all the cops these days spend they're time pullin over the rice burners with coffee can exhaust and gutted kitties, and all the rice burner drivers think they got power........ha ha ha, wait until they race me!

 

Actually, there were cats on 99.5-2003's because I have an 02 and it has one. Some came with them some not. Otherwise why would there be a "cat delete" pipe sold for 7.3's? As I understand it, in 02, manuals got them, but not autos. Other years who knows, I think some autos got them too. It differed from year to year.

 

well you may be right, i know i have a 01 f350 with no cat, came that way straight from the factory as i had ordered my pickup through the dealership. who knows, there is probably an assortment of psd's with and without cats.

 

ColtM4 is right, 99.5 and on it depended on where the truck was built and was shipped to.
Thats what a local stealer told a guy i work with.

 

Mine is a 97' auto and it has a cat, damn I hate cats, the hairballs and such.

 

i yanked my cat off last weekend actaully. after running just the cat and about 2 feet of pipe for a couple of weeks, i tried swapping. now i'm running the stock '95 muffler (this year was a flow-through), with a pipe coming out the side in front of the wheel. so far as i can tell, it sounds good without much turbo flutter. spent around 2 hours cutting and welding my old pipe into the right shape, but i got it and i'm happy with it. i just threw the old cat into the yard in case i need it later on. if you'd like to see the setup email me and i can send ya some pics. i know its illegal, but the Sheriff's hardly ever stop us for noise, mostly just when we're kicking up dirt on public property :-P

 

OK, jeeze, looks like everyone has different information! My 1997 250 PSD with auto tranny has a cat. And I understand/agree with ColtM4 that “A catalyst is a material to enhance chemical reactions by lowering the energy required for a reaction…” so unburned fuel is (without the cat) going to dump out the tailpipe (and into the EPA sensor at the testing station). But I read in someone’s post (I think Quadzilla posted it) that in Washington state they only inspected for opacity – thus the “soot converter” remark by 78fordman makes sense.
So what I think I’ll do is install a “cat delete” run the truck thru inspection and if it passes good, if not back to the cat.
Do any of you guys have an old cat that they want to get rid of?

 

I gutted my cat(eww!) and it reduced a lot of turbo lag, so that makes it a must do for 7.3's, but I would definately hang on to that cat if you remove it. I run a trucking company and the EPA has its cross hairs on commercial trucks lately so I'm guessing our pickups could be next, considering how many diesels are being sold.

 

My '99.5 never had a cat. I just replaced the original pipes with a 3 1/2 to 4" from the group buy.

 

My auto early '99 has a cat, but not for long. Magnaflow will take over 3.5" down to 4" pipe/muffler once I receive it this week(?) Postal closed tomorrow...

 

Technically it is a catylitic converter and is supposed to reduce soot, but the reality is it only reduces the small portion of unburnt fuel at normal continuous operating range, and I say this because if you romp on it, you still get black smoke. Part of the reason it happens is because you have fooled the computer into somehow dumping fuel into the cylinder with not enough air. Under normal operation there is a small amount of unburnt fuel aka soot, or other less than visible hydrocarbons and that is what the cat is supposed to get rid of. I agree, the cat is a must go item, but use the cat delete pipe and save the cat in case you need it. Fortunately, I live somplace where they aren't testing for opacity yet, but I'm sure they are working on it. Unfortunately, I can't justify a new exhaust yet, but maybe if they keep salting the roads like they did last winter and I'll need one soon and I'll delete the cat. Pulling a cat is much cleaner than gutting it, less blood and gore left over. Incedentally, I think the 02's with a manual have a cat because the computer allows for more fuel or the fuel programming is more forgiving than the auto, which results in the higher hp rating for the maunals and the way to keep it "legal" was to add the cat. This I think is also the reason why for the few people who have test driven or own a 6.0 with the manual feel that there is less low end power, because the engine is programmed to not dump fuel at low rpm, to prevent black smoke. I'm not sure what the test protocol is in washington, but I think I read someplace that the kalifornia "stab" test is to just romp on it from idle and require no black smoke.