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-   -   lose the cat? (

rancherman 07-15-2010 10:57 PM

lose the cat?
hey friends, I use my pickup much like a horse here on the ranch. And as you would expect, tall dry grass rubbing on the cat sure can ruin the day.
before I reconnect the exaust to my re installed 5.9 gasser, I was wondering about gutting the cat before doing so. I wouldn't do this to a fully functional cat, this one has 250k miles on it, and is either partially plugged, or crumbled up inside.

I am wondering if a performance chip from SLR motorsports, (or others) would sense the richer exaust from lack of backpressure, and make the necessary adjustments?

Also, putting a reman distributor in the replacement engine. Are there marks on the block for timing? This is the first dist I have removed from a computer timed engine.

mAs 07-30-2010 04:21 PM

Well my friend, where I live we do not require cats so mine was literally chopped out with my trusty old sawzall and replaced with a custom made Y-pipe I welded up myself from some heavy gauge galvanized electrical conduit, its not pretty but it works and sounds MEAN. I drilled a hole in the Y-pipe in the joining area to install the 02 so the computer would not get pissy or ruin my gas milage. It will depend on your year, I have a 94 so i only have a precat sensor to monitor the stoich, if you have the dual sensors you will need a fake 02 for the postcat 02 or the computer will throw codes and from what i read occasionally cause driveability issues.

I don't know if i would run a gutted cat, you create a pressure chamber then, going from like dual 1.75" to like 6" opening back to 2.25" outlet... that is very turbulent and will also sound rather raspy (like a rice box (aka Honda)). I know this from personal experience because I tried that first and did not like the results so made my custom Y-Pipe. I do sheet metal work for a living and own two welders so it was no problem for me, but its not that expensive for an aftermarket Y-pipe from B&M or whatever. like 30bux or so.

I am not too sure about the SLR chip, my cat was all broken up inside and rattled real bad when u tapped it, or gave it a bit of gas. Removing it for me made a modest power gain because there was no more blockage. The exhaust does for sure smell a bit more gassy, but I would expect that with no CAT to clean things up. I don't think it smells gassy because of less back pressure... but I could also be wrong. Just my opinion :>

Jayhawk320 07-30-2010 05:54 PM

how would you make one of these "fake o2 sensors"? i know for diesel's with DPF you can put resistors in-line to still give the computer a reading. does the same apply?

mAs 07-31-2010 03:29 PM

Im not quite sure how exactly my friend makes these devices... regarding fakie 02's

I am the mechanic and sheet metal guy, hes my programmer and software guy who owns a commercial voice over IP company... Ive known him since grade 3 and he is the computer wizard in my books. Taught me how to build my own computers and what not.

From what I gather though, yes its is some resistors. The fake 02 my friend gave/built me has a PIC controller though, it takes regular 12V power and it goes inline with the post cat 02 sensor, you then can just dangle the post cat sensor under the frame somewhere in the open air, as long as its plugged in it wont throw codes... does not have to be installed in the exhaust. Mind you, I am somewhat taking a guess that it would work for a OBD-II Ram, as my Ram has only the single 02 so I do not need the fake one. The fakie 02 my friend built me was for my 98 Bonneville SSEi, and it works fine on that OBD-II car with deleted cat and dual 02's.

He has done some crazy shit for me in the past, custom chip for my 91 Buick Lesabre Limited for higher octane and to support my ported heads, LIM, CAI, and Harland Sharp 1.9 roller rockers, he made me a serial line driver for the ALDL port to interface with some ALDL software this Australian company makes out of old serial mouse parts so I get a laptop screen full of swankie stats in real time while I drive... He even put slap shift tranny contoller in his dodge intrepid from a eagle talon TSi. He does crazy shit and takes him maybe 2-3 days tops. I could see if he would like to mass produce his PIC controlled fake 02 sensors.

98sst 07-31-2010 03:32 PM

A word of advice, don't go with SLR motorsports. That, and other ebay brands, are not legitimate. The best one for you to look at is SuperChips.

As far as gutting the cat goes, I'd be a little skeptical if you have to try to pass an inspection or have emissions.

whi3500mag 08-03-2010 10:43 AM

I would have to agree super chips is the wat to go i have no cats on my truck and its a 2000 my doesn't through any codes of anykind so i would just go with or with out

carrayz 08-03-2010 10:58 AM

if you do not have emissions control were you live go for the cat elim.checked around a lot got good advice here the superchip is the way to go!!!

Jayhawk320 08-04-2010 10:16 PM


Originally Posted by whi3500mag (Post 274898)
I would have to agree super chips is the wat to go i have no cats on my truck and its a 2000 my doesn't through any codes of anykind so i would just go with or with out

and your truck runs alright with no o2's? my understanding is that the o2's are what tells the computer to rich/lean the mix, correct me if i'm wrong randy

whi3500mag 08-10-2010 02:44 PM

I still have the o2 sensors they are located befor the cat on my truck

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