Gutting the Cat

[GoBlueHummer]

I know it's done but have any H3 owners done it? I have an '06 so it is a serious consideration but but I'm just a little apprehensive.

 

[erdlen65]

I've done it on other cars but never on my 3

 

[06 H3]

I think one guy did it back on the old forum days...he also did some aftermarket throttle body. His name is escaping me though.

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[M22KLARS]

Do you have emissions testing where you live? If not... cut that ****er off.

 

[GoBlueHummer]

No emissions testing, no inspections at all. I really can't think of a good reason to leave it intact. I guess the worst that could happen is I have to replace the CC if for some reason things went badly.

 

[M22KLARS]

Seriously I wouldn't waste my time gutting it when you can just cut it out completely.

 

[Scarsman]

I'm not sure there would be any point in removing/ gutting it. Modern cats are very different from the original ones that started the removal/gutting movement. They really aren't very restrictive at all. The old ones quite literally plugged the exhaust route, but modern ones flow quite well.

I discussed this at length with Catco when I was doing an exhaust on a past truck I had, and ended up leaving the cat per their recommendation.

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[elripster]

I'm going to echo Scarsman, modern cats flow very well. If want performance and don't need to pass smog you can do more with engine tuning than the rest of us in smogville can.

Frank

 

[Happy Hummer]

I'm going to echo...echo... modern cats flow very well and it is really not ness...
to remove them.

Chris

 

[erdlen65]

Even If they do flow well it's still a restriction, and if your trying to squeeze all the free power you can and you have no inspections or emmisions I would gut it or cut it out. Where I live we have inspections but no emmisions and any vehicle I have owned and changed exhaust I have either gutted or removed the cats. If u do cut it out take it to a scrap yard they're worth about $70 haha might get ya half a tank of gas

 

[Pappibri]

Mine is still intact. I see the reasoning by all. Sure it is just a little bit of restriction, but a whole bunch of littles add up to a whole lot. Once can gut it and do all the engine mods also.. Might as well get all you can out of your rig. When you have the I5, every little bit adds up...

 

[GoBlueHummer]

I understand what you guys are saying. There is a dyno sheet posted on the 355 forums that demonstrate a solid +10 in hp and torque with a gutted cat however, people sometimes go a long way proving their point and just because I saw it on the internet doesn't mean t's true. Many guys over there have posted on the perceived benefits so it lends some creedence I suppose.

I am not hung up on getting every bit of hp I can but more concerned with being as efficient as possible.

Hmmm.....

 

[MaxPF]

I'm pretty sure the H3, like every other modern vehicle, has post-cat O2 sensors. If you gut or delete the cat the PCM will throw an emissions code and light the MIL. A saavy tuner can delete the post-cat O2's to "fix" the problem. Personally, I like cats since non-catted gas engines stink. Even clean burning modern computer-controlled engines stink without cats. I dunno, maybe that's because I am used to the smell of diesel exhaust

The guys above who say the modern cats are very low restriction are correct - your muffler is a bigger choke point than your cat. IMO, if it ain't broke, leave it alone.

Finally, I should mention that when I still had a guzzle-ine engine in my Blazer I smacked the cat on a rock during a wheeling trip. It was a ceramic element unit (most common type), and it plugged and then started to come apart, and the engine ran like crap. Eventually, it blew chunks of the honeycomb core out over a period of several days. Truck ran great after that :wink: When I pulled the gasser to swap in a deezel, I removed the gas exhaust and in doing so got a look at the inside of the cat. It was COMPLETELY empty! Self-gutting cat!! :horns:

 

[GoBlueHummer]

lol I had a cat that gutted itself on an S-10. It must have become pulgged and built pressure and blew the little bung plug out. It sounded like a shotgun and scared the **** out of me.

You are correct, the 3's o2's will throw a code; except in the 06's.