View Full Version : dumb question but which one is the cat?
12-06-2002, 11:22 AM
im gonna hollow out the cat this weekend. I see the muffler, which is farthest back from engine, and then about 1 foot away, i think its the cat. thats all there is on the exhaust pipe. from there on up to the turbo its clean. Ive heard of a resonator (i think.) I just dont want to start sawing away and then find out it was the wrong thing
12-06-2002, 11:28 AM
The cat is the round thing that is closest to the engine. It sit under the passenger side of the cab and has a taper to the front of it.
12-06-2002, 11:37 AM
cool, there she sits. Now i just gotta figure out how i want to do this. I dont have a welder, but a friend does. perhaps i can rig some sort of deal with clamps. I can figure out something. thanks for the reply.
12-06-2002, 12:34 PM
i did mine at the beginning of summer. i took a crowbar/pinchbar/prybar- whatever you want to call it and went in through the 3" side. it helped a ton that i got a big hammer (the smaller sledgehammr types). it's a pain to go through, but once you put a hole through the middle, the rest will start to crumble and fall apart easy. just don't breathe that stuff.<br><br>Tom
12-06-2002, 12:50 PM
what will that help? will it improve air flow??<br>
12-06-2002, 03:48 PM
I decided to keep the Cat but remove the gutts.<br>That way, if you look under the truck, it looks all stock. <br>What they dont know is, the cat has been hallowed out.<br><br>Now, to do this is a different story!<br>It took me and my good friend about 4 hours to get this done.<br>The cat was heavily rusted on the exhaust pipe. We used torches, hammers and an air grinder to get the cat free from the exhaust down tube.<br>Once it was free of the down tube, we left it attached to the larger diameter tube leading into the muffler.<br><br>Once we got it free of the down tube, what we found worked the best was the handle from the floor jack. <br>We took the hand out of the floor jack and used a rubber mallet to pound the jack handle into the honey comb catalyst.<br>Working the jack handle in circular motions, we were able to break out most of the catalyst. <br><br>When the catalyst was gone, we placed the cat shell back on the exhaust down tube and tightend all the fittings.. and off I went.<br><br>Looking at the honey-comb matterial, most of it was plugged up pretty good. I'd guess that a little less than half of it was plugged with black soot.<br>This means that only just over half of the exhaust was flowing through without impedence.<br><br>I did not notice any performance gain post cat modification. I do not have a Pyrometer either, so I cant address the exhaust temps. However, I would have to assume that the exhaust temps have gone down with the removal of the restricing honey-comb catalyst.<br><br>One thing to note:<br>The trip I took to California (Pre modifying the cat) I got 20 mpg. <br>The trip home (Post modifying the cat) I got 21 mpg. <br>There were weahter differences and traffic differences that might be relavent, or maybe it was better mileage due to the increase exhaust flow. <br>I dont know, and Im not trying to tell you that modifying the cat will give you better mileage. <br>That is just what it "seemed" to do for me.<br><br>Rich.
12-06-2002, 05:31 PM
Cat removal made no diffefence what so ever on mine. The truck had 155K on it when the Cat was pulled. IMO it was a big waste of time and effort. You could easily see light through it, keep in mind its built in a "corregated" manner and if you look through it at an angle it appears clogged. <br><br>On gutting a Cat. The Cat has cadmium in it, a cancer causing "heavy metal" if you gut it do so in a manner that all dust/debris are contained. WEAR A DUST MASK! I would not mess with it, if one were found on the road in pieces Haz Mat would be called! <br><br>Michael
12-06-2002, 08:00 PM
The Cat has cadmium in it, a cancer causing "heavy metal" if you gut it do so in a manner that all dust/debris are contained. WEAR A DUST MASK! I would not mess with it,<br><br><br>Ah ha! That it explains it! [eyecrazy]<br><br>We were very careful when we did that.<br><br>Rich
12-06-2002, 08:19 PM
Or take a 5' piece of 3" pipe, 2- 3"OD connectors, 4 clamps, and loose both restrictions. It took me an hour to do last week. As long as the windows are up the noise is barely noticeable 8).
12-06-2002, 08:31 PM
Tell ya what guys- My cat did plug.I could not get any boost, egt's were through the roof. If I put my throttle to the floor and counted to three the pyro went to 1000*!!! :o :o :o It is amazing what an 18" long 1" dia. masonry bit can do!!
12-07-2002, 01:13 PM
same thing that happend to Mntom happend to me. It started out frrling life the truck was loosing power then the egt's started riseing.<br>Aaron
12-07-2002, 07:40 PM
Hey BigBad,<br>I took the cat off my truck when the truck was stock and immeadiately noticed a big difference in the power and the sound of my poor old choking 95. I dragrace and had some Hooker Header 4 to 3 reducers around that were purchased for something else, They worked perfecy for making a "test" pipe. This was done 3 years ago, but recently replaced with a complete 4 system. Wish I had saved my money and bought the 4 from the start.
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