catalytic converter?

[shady1up]

Is there much of a performance gain to be had by ditching the catalytic converters for straight pipe? Some times it sounds like wrenchs are rattling in them 2001 yukon 5.3 141,000

 

[Physh1]

You can gain a little performance if they are removed & you get a matching tune. No smog checks where you are?

Cameron

 

[shady1up]

Nope no smog checks in my area of colorado and I thought about doing the egr delete with my tune too. Has anybody had any issues with the egr delete?

 

[soulsea]

Actually, even if there were smog checks, most if not all cars built since 2000 would pass anyway ... as I understand it the catalytic converter is one of the most redundant and unnecessary pieces of equipment on any fuel injected car. It takes fuel to keep it hot to function properly.

There's a great thread about it in another forum I frequent: http://www.abovetopsecret.com/forum/thread572015/pg1

I'm not good with mechanical stuff so I don't know what the HP gain would be by removing it, but it is fundamentally a scam.

Cheers!

 

[07Burb]

Intriguing. I'd never heard that!

 

[brad6603]

I had the so called rattling noise near my cataylic converters on my 2001. Come to find out it was the downstream 02 sensor. I unscrewed it out and you could hear it make a racket when you shaked it. It was like it had busted inside. I later found out it is made of a ceramic material just like a spark plug. Replaced both rear 02 sensors and the rattle sound went away.

 

[ezdaar]

Donot do the egr delete, unless you want to loose aprox 2mpg, The performance gains are so minimal that you need a Dyno to see the difference.
But the loss in Fuel is felt immidiatly in your wallet..

As far as the cat's yea remove them for fakes and get a good tune. the smog test will never know the difference. only visual test will.
I replace mine with hollowed cats, that have a tube stuffed into them to keep my flow pattern the same as a straight pipe, but passes visual.

 

[07Burb]

Where you buy fake pass threw cats?

 

[ezdaar]

Fake Cats, click me

 

[TogaPC]

I could be wrong, but from what I know the performance gain from removing cats is negligible since the stock cats flow very very well. It will be quite a bit louder though. These modern engines are made to work with the cat and EGR and all the other emission equipment to produce great power and a minimal amount of noxious gases. In other words, you don't stand to gain much, and it's a FEDERAL offense.

Does anyone have definitive dyno results or track times that say there is a gain?

 

[chacho44]

removed mine and the truck sounds fine, very little diff in sound but still running stock muffler

 

[Jay]

Modern converters do not rob enough power on a bolt-on vehicle to be worth the trouble of removing them. Like anything else they are designed for a flow rate. The stocker might cost a 5.3 5-10hp at 5k rpm, and considerably less in the lower rpm. The stock muffler robs a lot more than that. If you mod a stock 5.3 or 6.0 to 400hp it'll keep up fairly well. At 500hp (assuming you are turning 6500rpm or more, or using N2O/boost) then the stock converter probably will be eating a lot of power (20hp+)... there is a sharp break-over point to where it really starts robbing power as you increase the flow rate/load rate due to turbulence (study up on Reynold's number for fluid flow).

Personally, for a road vehicle I'd rather keep the cats. Just size it/them to the power level and not have to smell those rancid fumes.

 

[TogaPC]

^+1

 

[sstuck2]

removed mine and the truck sounds fine, very little diff in sound but still running stock muffler

hey man, hate to revive this ancient thread, but I have a 03 z71 tahoe and I want to cut the cat off but i dont want a check engine light on all the time. Did you have any issue like that?

 

[DCT]

hey man, hate to revive this ancient thread, but I have a 03 z71 tahoe and I want to cut the cat off but i dont want a check engine light on all the time. Did you have any issue like that?

How do disable the check engine light after removing the cats?

 

[franksbanks]

How do disable the check engine light after removing the cats?

a custom tune- you can disable the bottom 2 (post cat) sensors-

the o2 sensor above the cats (pre cat) are needed for the truck to operate-

if you dont want to spend 399+ for a tune- the alternative is to use o2 simulator/Eliminators (google search) to keep the voltage registering that theres an o2 sensor actively working.

 

[livingez_123]

Federal offense, your no fun.

The smog check here in Portland, OR is a simple plug in the OBD port and a look with a mirror under the truck to see if the cats are there.

 

[Gzes]

We only got safety inspection here I un gutted cat

 

[jmgak47]

Removing the cats should give you roughly 8 or so hp to the wheels, a slight loss in throttle response and a CEL.

You can eliminate the CEL with custom tuning or spark plug nonfoulers, a cheap alternative.