Exhaust question..

Cat converters are too expensive!!

What kind of potential problems would I run into if I just took the cat out of the loop?

Isnt there an O2 sensor right in front of the cat as well as on the manifold? Can that be tapped into the pipe or use of a welded nut or something by the location where the cat once was, or is it not needed?

Just a couple questions I have before I make the run to the guy to get this done.

(I can get this done, so please dont lecture me about the EPA and exhaust shops......he he, I just want to konw what if any problems i may run into if the cat is left out of the new exhaust, so far NO emissions test in Nebraska)

Thanks,

Cory

csr_011 said:

(I can get this done, so please dont lecture me about the EPA and exhaust shops......he he, I just want to konw what if any problems i may run into if the cat is left out of the new exhaust, so far NO emissions test in Nebraska)

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:lecture: :lecture: :lecture: :lecture: :lecture: :lecture: Federally-mandated cat? Making it a Nebraska-only vehicle that won't pass inspection in most other states? (Dare I say it?)..Giving the anti-recreationalists and anti-internal combustion folks more ammo? Off soapbox now...

I picked up a replacement cat from NAPA a few months back with the O2 bung and all, and the price wasn't bad. I might be able to dig up part numbers and price if I still have them.

Yucca-Man said:

:lecture: :lecture: :lecture: :lecture: :lecture: :lecture: Federally-mandated cat? Making it a Nebraska-only vehicle that won't pass inspection in most other states? (Dare I say it?)..Giving the anti-recreationalists and anti-internal combustion folks more ammo? Off soapbox now...

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That being said...Your profile says you have an '87 so if you don't care about the environment you can put a resonator in place of the cat. Some older Jeeps came equipped that way. If it were an OBDII Jeep you would run into problems doing this.

csr_011 said:

What kind of potential problems would I run into if I just took the cat out of the loop?

I just want to konw what if any problems i may run into if the cat is left out of the new exhaust, so far NO emissions test in Nebraska)

Thanks,

Cory

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Loss of performance. Your low end tourqe will suck.

This aside from all the EPA stuff...buy a cheap cat.

Rev

u lucky guys that live in states were you dont need to pass emissions. or run a cat. well i just bought a dynomax for like $53 off jegs. and as soon as i pass emissions im ripping my muffler off an putting on this glass pack i found on the side of the road

Rev Den said:

Loss of performance. Your low end tourqe will suck.

This aside from all the EPA stuff...buy a cheap cat.

Rev

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X2 My low end sucks off the line since I gutted my cat. I can't wait to get my new exsaust and intake.

Suprisingly some people claim a noticeable gain in power after gutting the cat...atleast thats what i have found after searching this topic several times. Robz95xj: what muffler are you running (if any) behind your gutted cat? Most everyone else feel a low end loss after gutting the cat? I was thinking about gutting mine and adding a flowmaster 40. I've heard that a gutted cat will help cut down interior resonation.

Right now its a Flowmaster 40 delta flow

I figured that i would get this response....he he. I do care about the environment, its just that my pocketbook cant afford those measures right now...

I also planned on going the route of buying the pieces and bringing them to an exhaust shop. I just wanted to know of the kind of performance loss/gain that would happen without the cat. I think that has been answered.

I did price a couple of cats at auto parts stores, not too bad, the exhaust shops around here qouted me $170 for the cat, $150 for the muffler and new pipe from the cat on back, labor included in those prices, thought that was a bit pricey but pretty competitive. Business is business.

Next question:

Where can i get the down pipe from the manifold with the crimp in it? Then i can bring in the new cat, muffler, and down pipe and have them install it with their pipe to fill in the rest. The reason i ask this is that we couldnt get the bolts broke on the manifold to the pipe when pulling the motor for the rebuild, so i cut the pipe as close as i could and they rewelded it at that cut when the engine was installed. I figured i might as well do it all when i do get around to doing the exhaust.

Thanks,

Cory

El bumpo.

Where can the crimped downpipe be ordered from?

Cory

xjfish said:

Suprisingly some people claim a noticeable gain in power after gutting the cat...atleast thats what i have found after searching this topic several times. Robz95xj: what muffler are you running (if any) behind your gutted cat? Most everyone else feel a low end loss after gutting the cat? I was thinking about gutting mine and adding a flowmaster 40. I've heard that a gutted cat will help cut down interior resonation.

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Yeah -- if the cat is clogged to the point that the engine will barely run, like the one on my 87 MJ when I bought it, then gutting the cat will result in more power. But the engine was calibrated to run with a cat, and removing a properly functional cat will reduce low and mid-range torque, although it may gain you high-end horsepower.

With owning an exhaust shop in the past....and being in a state with no e-checks...I've found that on my "trail only" vehicles....as long as they don't read before and AFTER the cat, or just after the cat only, taking them off helps all the way around. If it has a sensor before and after.....or one that is just located after the cat, then it'll probably throw a code because it's supposed to read a change from before to just after the cat.

My current XJ is a 1988 and it has no cat w/a Flowmaster and I noticed a good improvement in bottom, mid and upper rpm ranges. I doubt that you'd get the same results with the newer, non-renix XJ's though. I'm not real familiar with the newer OBD-II or whatever the newer XJ's are using. It all depends on how your o2 sensor reads and if it's supposed to notice a change that's within a set of parameters that they program into it.

Summit racing used to sell a kit that you could weld into a "test" pipe....and it was for GM cats with o2 sensors before and after the cat. It consisted of some wiring and the needed o2 bung(s). It just simply fooled the computer into thinking that it was reading a change that was within the acceptable, pre-programmed parameters. I haven't checked to see if they still offer it...but if they do, you might look into one of those...or that particular manufacturer.

Aron

I don't like to plug business, but both 4wd and quadratec sell the pieces, plus the local part houses should also.