Catalytic Converter bypass pipe?

[jakec]

Probably more than guy with 52 posts.

Ha, my bad, I forgot that the number of posts you have directly affects your knowledge of vehicles.

 

[Jonathan]

Unless it being an ho vs. a renix will make that big of a difference, I'm gonna call bs. I'm not saying removing the cat is the best thing in the world, but I personally prefer to run without one. I run a cheap turbo muffler, no cat, and it runs great and has lots of torque. It purrs like a kitten at idle and doesn't miss a beat at speed. In other word, it does NOT run like shit. As far as emissions go, I believe keeping your vehicle properly tuned is far more important.

You can believe whatever you want, but it won't change the amount of junk you're dumping out your tailpipe without a cat.

I'm only an amateur mechanic, but I work with the people who are developing the cutting-edge equipment for monitoring what really happens with ICUs when they're in use, and the data is astounding. The difference between a catalytic-equipped vehicle and one without is immediately clear even when 50 yards behind the tailpipe. By the way, that measurement is made on the road: this equipment is mobile and I wouldn't be surprised to see regulatory organizations or law enforcement deploy it widely in the next 20 years.

With a replacement converter only costing as much as two or three tanks of gas then there's really no excuse to not run one in the long run. For the minimal cost and tiny performance loss (if there is one), we can afford to run a clean show, especially considering the image problem that off-roading and SUVs have.

 

[jakec]

Jonothan,

Actually, that is interesting information. Thank-you for sharing. It's hard to argue with actual test results in real life scenarios. But, you only have 7 posts, so I'm smarter than you (j/k!) I still believe what I stated about performance, but I may have to rethink my thoughts on emissions.

 

[rikard]

My son in laws YJ with the 2.5 developed a rattle and then a restriction in the cat. Since we were far from home we just replaced the cat with a straight pipe and drove home. The following weekend we replaced the pipe with a high flow cat from the zone (less than $100). He could detect no difference with the straight pipe or the cat. Many of the early cats were restrictive but the newer ones are much better and cheaper. Changing to a free flow muffler did make a difference. As stated by a previous poster legally you are supposed to keep all of the emission devices that the vehicle had as OEM. You also have to disclose to a buyer if any of the emission equipment has been removed. If you are going to discard the cat use a straight pipe not flex pipe.
YMMV
regards
rikard

 

[Skwerly]

I've heard both, but really either way, it doesn't make sense in the long run to go through all the hassle of eliminating something the vehicle may need to run properly, OR at the very least need in order to pass smog (in smog states). Mine just recenly went bad (demolished it on the trail, sounded like it had a softball in it afterward haha), so i went to Kragen and got a universal one, like 58 bucks. Looks nice, does the trick, and it's smaller! Just my two cents.

 

[j99xj]

get out the popcorn, I'd like to hear about this!

It's true.

The 4.0 doesn't need backpressure as long as it is tuned accordingly.

You can't expect a high flowing exhaust to do anything more than create excess noise unless the ECU can compensate for the increased flow by adjusting the fuel injectors and ignition timing.

Fortunately for us we have fuel injection (and a handful of helpful sensors) so that our exhaust mods will increase power. (the results are there, but aren't staggering)

As it has been said, "its all about airflow" is very true. You can increase airflow on any engine with careful intake and exhaust mods but eventually you will reach a point where you will have to either increase the size of the engine, increase the rpm capability, or both.

But there are mechanical restraints. That's why big engines simply can't rev as high as the smaller ones because the parts will break.

If find it very funny to read about the big block lovers boast about their cubic inches and low end torque and then get destroyed by a much smaller "gutless" engine on the racetrack.

Don't believe it? Look at Formula 1. Those engines are a very conservative 2.4 liters but make over 700 hp without boost or nitrous.

Anyway removing the cat won't make much difference because modern cats are of the "honeycomb" type that flow quite well. (unless completely shot)

 

[F9K9]

OK, I don't want to start a new thread or high jack this one but, I am a retired ( I retired in '02). US Forest Service Law Enforcement Officer/Agent. My expertise was in the counter drug effort and I was in a multiagency task force. We did assist the local tree cops when time allowed. Here in KY we had the Daniel Boone National Forest closed down to all logging and ORVs (off road vehicles) by the federal courts due to grass root environmental groups filing suits.

In the ORV arena, a few bad apples where ruining it for everyone. The agency was mandated to put a halt to the problem ( In KY USFS officers have full state peace officer staus AND DEA powers) and I found myself working 7 days a week. Five were counter drug and two days were in a marked SUV writing tickets on weekends to morons that wouldn't follow a few simple laws.

Your state will start inspections with all of this pressure and we need to police ourselves. Unless you have a "tow rig" and trailer for your trail rig then, I would remain as low profile as I could get.

KY was one of the last states to mandate the seat belt laws and many of the other vehicle related laws. We don't have mandated inspections yet but, we will! If, your state doesn't have inspections yet, you will! The federal governent will cut off federal highway funds in the future if, they don't.

I guess what I am trying to point out is that we all need to try to keep the tree huggers out of ammo, especially now! With all of this global warming and associated "scares" becoming rampant. If, you want a son or younger brother to enjoy what you are enjoying then please stay legal.

If, you don't think the "tree hugging" assholes are reading forums like this then you are woefully behind the times.

Wake up, guys! I am painfully new to all of this and want to see it continue!

 

[Rev Den]

Ha, my bad, I forgot that the number of posts you have directly affects your knowledge of vehicles.

Has nothing to do with post counts as my friend joked about.

Has more to do with me.

My take is he will do what he wants...run it for a while...and realize, hopefully, that it was a bad idea.

Rev

 

[Blaine B.]

Actually I think the backpressure created by the existence of the cat improves performance?

Something I've heard.

 

[j99xj]

Actually I think the backpressure created by the existence of the cat improves performance?

Something I've heard.

That is because the engine is designed to run in conjunction with a catalytic converter. It has to do more with air/fuel mixtures than backpressure.

Anyway modern cats are very efficient. I replaced my stock cat with a "high flow" unit that did absolutely nothing performance wise.

My "high flow" cat is at the top of my "worst mods" list. It was a total waste of money.

At least my dynomax muffler/tailpipe produced a noticeable difference and a reasonable sound for the money.

 

[badron]

Well, for all the tree huggers. A cat on a 92 by now is a waste anyway unless it was up on blocks most of the time.
At 50,000 most cat are just a fat spot in the poop pipe. The new 3 kitty system hold up better. But 100,000 is a lot on them to.
For what it counts: I still have the first car I got new. A 85 Cavalier wagon. That has passed Ohio tall pipe sniffing test 4 or 5 times now. With a gutted kitty and with fair numbers at that.

 

[Crush]

Is everyone crying about not running cats because it makes the vehicle run bad or because it kills the enviroment?In a way Im hoping its because you are worried about another person's Jeep performance.As for the enviroment......http://www.canadafreepress.com/2007/global-warming020507.htm. I have many more links.Let me know if you want more.

 

[law.74]

Is everyone crying about not running cats because it makes the vehicle run bad or because it kills the enviroment?In a way Im hoping its because you are worried about another person's Jeep performance.As for the enviroment......http://www.canadafreepress.com/2007/global-warming020507.htm. I have many more links.Let me know if you want more.

Yes, global warming is BS. Ask any academic meteorologist that isn't supported directly by the recent congressional task forces. The warming climate is, however, giving the environmentalists ammunition.

The fact of the matter is catalytic converters make the air cleaner to breath.

http://en.wikipedia.org/wiki/Catalytic_converter

 

[j99xj]

I believe in global warming....I also believe in global cooling. It is cyclic. Things go up for a while, then go down, and sometimes they stay the same for a while. It's nature.

But I do NOT believe they are the direct result of human activities.

It has much more to do with the sun and cosmic rays, which I can safely say are completely OUT of our control.

But I think most will agree that catalytic converters have more pros than cons.

 

[Crush]

Well this is how I see it.If Global warming is not the fault of man,which I believe its not,then lets get back to cars that didnt have cats. and other emissions crap so they can be more affordable and less money to have repaired.At any rate,if you want to run a cat. so that you feel you are doing your part to keep the air clean then thats great.I on the other hand enjoyed saving 100 bucks on my exhaust.

 

[red91]

Has nothing to do with post counts as my friend joked about.

Has more to do with me.



Rev

:idea:


Glad to see that some can stil read between the lines.


Rev has been working on rigs before you were probably a sperm...


I doubt you'll get that one either.

 

[Blaine B.]

lol

 

[JNickel101]

I have a 2000XJ with the 2 "pre-cats" and 1 "main cat" that sits just before the muffler. Was running a Magnaflow muffler up until last Friday. Had a local shop put on a Twister (interesting design, corkscrew down the middle of a 5" pipe...anyway) - since I bought this jeep a year and a half ago, I replaced the headpipe containing the two mini-cats with a new OEM one and got a new "high flow" main cat - I noticed the BIGGEST difference when I went from the Magnaflow to the Twister....

personally, I don't think removing the cat will do much for performance, but a NEW cat vs one with 130,000 miles on it....yeah, that is noticable...

 

[90Blue_XJ]

:idea:


Glad to see that some can stil read between the lines.


Rev has been working on rigs before you were probably a sperm...


I doubt you'll get that one either.

Well he has to be an old fawker if he was working on rigs when I was a sperm/egg because if I make it to October I will be 60.

And Rev doesn't make points with these noobies by calling them morons either.

 

[Blaine B.]

I have a 2000XJ with the 2 "pre-cats" and 1 "main cat" that sits just before the muffler. Was running a Magnaflow muffler up until last Friday. Had a local shop put on a Twister (interesting design, corkscrew down the middle of a 5" pipe...anyway) - since I bought this jeep a year and a half ago, I replaced the headpipe containing the two mini-cats with a new OEM one and got a new "high flow" main cat - I noticed the BIGGEST difference when I went from the Magnaflow to the Twister....

personally, I don't think removing the cat will do much for performance, but a NEW cat vs one with 130,000 miles on it....yeah, that is noticable...

Isn't there something about it being illegal to dispose of a cat unless it is bad? Not that I care but perhaps some sort of factoid right here :yelclap: