Remove/gut catalytic conv?

[RayburnRacer]

getting ready to go in with the stroker, i was wondering what everyone does with the cats just down stream of the donut gasket. Remove it, gut it, leave it alone (rather not since they tend to be rather restrictive). Im sure it will upset the O2's so does everyone dummy them or just let the CEL glow.

Also, what oil is a good choice to break-in the new motor for the first twenty min and then the first 500. Up for suggestions...

[yuppiexj]

Don't remove the cats.

Red this brief article http://www.importtuner.com/features/061 ... index.html 1HP and 1 Lb/Ft of torque was gained.

Unless it's going to be an unregistered off road only vehicle.

[amcinstaller]

depending on where you are, you could run without one. we have no emissions testing around here (alberta canada), but we have an ambundance of mosquitos to kill . but really, why not just grab a high flow cat if youre concerned about the power? keep everyone happy and keep the mosquitos biting

[RayburnRacer]

The link below is what Kennebell found out about the hp difference with cat or no cat. 5hp at stock and 10hp at 300hp.

http://www.kennebell.net/techinfo/dodge ... 40tech.pdf

Im in a state and county that doesn't require cats or does emissions. I would love the extra horses if there is a way to dummy the computer to make it think the cats are present. I use simulators on my camaro and vette to fool the computer. Is someone using these on a jeep. The camaro and vette computer doesnt change fuel curve to compensate for the cat it just throws the CEL. I heard the jeep comp will run a rich curve to try and heat the cat. Undesired.

Thanks

[5-90]

Just use a high-flow cat. I tend to run BBChevvy cats on my Jeep - doesn't impact emissions at all (I'm subject to the Air Police.)

Random Technologies also makes some good high-flow units. I don't think they have any that are specified for use with the 242ci, but I'm fairly sure they can help you pick one if you ask!

Let's not give the Greenies any more ammo to use against us, okeh?

[RayburnRacer]

Im not going to run the main Cat just because i would need to buy a new one and since the O2's are not focused around the main cat. But, the pre cats which are monitored by the O2's are something i would be concerned gutting or removing with out the ability to trick the comp to think its there and working.

I live in in texas and work in a refinery. I do engineering that involves dealing with the EPA on a regular basis. i don't want to spoil any tree huggers dream of living in a emission free world, but its never going to happen. In fact the the regulations the government is forcing on the petrochem and automakers is whats causing our country to turn to crap and eventually an economic crash. My company spend 3 million a qrtr on average because of so called violations. We spend billions of dollars on equipment to reduce emissions in which reduces productivity and cause us to make a crappier product. Which is passed down to you and i. You know that our plant can not throw a coke can into public trash because of it PH level. And our analyzers are measuring less emissions a day then comes out a million and half peoples ass. Your car gets produces a 1/4 less emissions, but get less than 1/2 the gas mileage it could without the bullshit. Global warming my a$$, ask washington DC if its warming globally there. Volcano's and ocean vegetation produces 85% of the CO2 in the world regulate that.... Sorry for the rant... Just not to worried about running a cat on my trail jeep...lol

I guess what i wanting to get at is, what do you guys that aren't running the pre-cats do to trick the computer or just run with the CEL and dont see much effect on the AFR.

[SilverXJ]

Let's not give the Greenies any more ammo to use against us, okeh?

x2 Use a high flow cat. Only $80 or less.

Im not going to run the main Cat just because i would need to buy a new one and since the O2's are not focused around the main cat. But, the pre cats which are monitored by the O2's are something i would be concerned gutting or removing with out the ability to trick the comp to think its there and working.

You can get rid of them using O2 sims. Google "02 simulators". There are several companies that make them, most of which you need to splice in your self. Casper use to make some really good ones which I have been running for like 7 years, but they were forced to stop making them. From what I have read the pre cats don't do much.. just for warm up. Its the main cat that does most of the work after warm up. Also, those down stream o2 sensor have no effect on fuel management. They just check the condition of the pre cats.

[RayburnRacer]

Thanks silverXJ,
I have a few simulators that I can wire in just wanted to make sure their readings didn't effect fuel curve.

Any suggestion on breakin oil. I have searched and don't comeup with many threads. Do most convien. oils contain adeqaute ZDDP. Or just buy the additive, I read that a few guys have good luck with royal purple, but not stoked about spend $50 for a 20 minute breakin.

[gradon]

I'm with you on ditching/gutting the precats(and I would never think of buying a 4 o2 sensor cali xj--thank Jah I bought the 95 m3, and not the 96-99s). I swear those precats have got to contribute to injector heat-soak issues. Someone posted a nice high-flow metallic cat that was like $40(+ shipping probably). The 01 XJ I just sold only had the 2 o2 sensors on each manifold and none downstream, so removing the main cat wouldn't have set a cel. How many o2s do you have?
Oh yeah I used Brad Penn SAE-30 break in oil for the cam break in and the first 500(well 600) miles and continue to use their 10w30 racing oil.

[IH 392]

The honeycomb in my cat fell out into the garbage can when I changed my header, the front half was rattling around in there and driving me crazy!, that was about five years ago and the CEL never comes on.
If we ever get emission testing around here the visual will show that I do indeed have a cat on there!

[SilverXJ]

I use Joe Gibbs BR30 break in for the initial cam break in. Then use either Valvoline VR10w-30 or Brad Penn 10w-30. I want to switch to Amsoil after about 5000 miles, but i haven't gotten hat far yet.

[gradon]

Here's the one I was talking about(it's ~$25-30 cheaper than the magnaflow):
http://performance-curve.com/410250-250 ... erter.aspx 2.5" w/o o2 bung
http://performance-curve.com/425250-25c ... tero2.aspx 2.5" w/ o2 bung
and they have other sizes too.

[RayburnRacer]

Reading the thread about what oil to run, i believe i will be using Brad Penn.. Any reason not to... and what intervals are you guys running brad peen for 3000, 5000?

I planned on using brad penn break in for the first 500miles. Should i go ahead and use it to the initial 20 min break in? Or a cheaper conviential with ZDDP additive.

Thanks

[gradon]

I would use a break in oil for the cam break in and first 500 miles.

[MrShoeBoy]

If you have a properly built and tuned motor a cat is not necessary. I came from a smog checking area and tested my Jeep stroker motor with the cat installed and with it removed. Both sniffer tests were under the allowable limits and were with in 10% of each other. Since then I havnt bothered to put a cat back on. This was done 3 or 4 years ago, there was a post over in the speed freaks section of JU with numbers. I just dont feel like digging it all back up.

AARON