Has Anyone Replaced the Catalytic Converter w/ a Bypass Pipe

trzrtree · **Posted:** Mon May 21, 2012 10:40 am

I've read allot of great posts on swapping out the restrictive muffler with a quality after market piece and a few brief comments about eliminating (or gutting) the catalytic Converter, but nothing substantial... Has anyone got any leads of a bypass pipe and what of the sensor? - Does this send the computer into convulsions. - Any solid info would be great (^_^)

trzrtree

CATCRD · **Posted:** Mon May 21, 2012 7:54 pm

There is no O2 sensor, if that's what you mean, so gutting or removing the cat has no effect on the computer.

trzrtree · **Posted:** Mon May 21, 2012 9:29 pm

Great! - So I was about to ask, if there is a trick to gutting the converter, but I'm getting information, that there would be no noticeable performance gain by doing so.... I guess a good "straight through" exhaust is the best bet?

AZ CRD · **Posted:** Mon May 21, 2012 9:50 pm

What catalytic converter?

Silverdiesel · **Posted:** Mon May 21, 2012 10:44 pm

Is it a particle oxidizer?
Got mine gutted. In Az Emissions still require it be there but they cannot tell what it is and even they call it a converter.

Silverdiesel · **Posted:** Mon May 21, 2012 10:51 pm

Also IIRC Chrysler has issued a technical bulletin stating the oxidizer needs to be replaced by 120K miles as they do eventually plug up affecting turbo back pressure resulting in overboost conditions and throwing a code. I had a muffler shop cut open and removed the material then braise back shut hence my gutted oxidizer.

PhilStubbs · **Joined:** Mon May 21, 2012 10:09 am **Posts:** 5

Not much of a trick. Wear a resperator(not a dust mask) and jam a broom handle in there till its all gone.

I have been tuning turbo cars professionally for quite a few years and I'm not buying the idea that the cats don't restrict flow. I am new to diesel performance but gas and diesel still "suck squish bang blow" and more air in means more needs to come out. Sure the housing of the cat is quite a bit bigger than the pipe on either side of it, but the cat material still(in my mind) takes up more volume of space than the larger housing adds. Turbos love free flowing exhaust and I have yet to find any negative effects from an exhaust that is "too big". Turbo engines, unlike N/A engines don't need exhaust velocity(don't confuse that with back pressure) post turbo. Pre-turbo, yes. The turbo manifold does need to be properly sized to keep velocity up and keep heat in the exhaust gas and not dissipating through the manifold.

DOC4444 · **Posted:** Tue May 22, 2012 6:17 am

GDE has gone on record as stating that there is no gain from gutting. There is more smell, though.

DOC

PhilStubbs · **Joined:** Mon May 21, 2012 10:09 am **Posts:** 5

I am going to keep my thoughts to myself on that subject. My thoughts don't bash GDE at all, but it would open a can of worms I don't want to deal with. I stand by what I said with 10 years experience in automotive tuning.

DOC4444 · **Posted:** Tue May 22, 2012 7:57 am

Phil,

Search the site for my dyno test results. You may find them interesting.

DOC

warp2diesel · **Posted:** Tue May 22, 2012 10:35 am

For a 2.8L CRD, get rid of the 2 1/8" restriction on the rear CAT flange, go 2 1/2" the rest of the way back and your back pressure will drop to 0.0 PSI. Even with a higher performance tune.
I ran a bunch of tests before and after and posted it.
My before back over the road pressure tests that ran as high as 5 PSI under high torque load towing a trailer. Others have posted dyno tests that show similar results.
Conclusion the CRD CAT (or Soot Trap) its' self is not a restriction but the 2 1/8" choke flange and the crappy stock muffler are the source of restriction.
We need to put this into a noob sticky.

geordi · **Posted:** Tue May 22, 2012 1:43 pm

Yea, I pulled mine and the CRD coasts a lot better... But the smell was worse on low sulfur or high sulfur than with ulsd or bio. I also opened the rest of the system... So my benefits might be b/c of what Warp said. I still might put the cat back someday, I know it is laying around somewhere...

Has Anyone Replaced the Catalytic Converter w/ a Bypass Pipe

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