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  1. #1
    Join Date
    Oct 2008
    Location
    Michigan
    Posts
    83

    Default Soot trap or cat?

    I just removed my nearly new stock exhaust system on my 96 and am looking at what some call the soot trap and the inside looks an awful lot like a cat. I do have the f vin engine which is not supposed to come with a cat. I am wondering if the dealer I bought it from replaced the exhaust system with an s code style. How do I tell the difference just by looking at it?

    The reason I ask is I will be trying to sell the old system and have no idea what, if any, the price difference would be for a cat vs a soot trap. Any help would be greatly appreciated! Just installed straight pipe for cheap and need to get rid of the nearly new (15,000 mi) old system, behind downpipe.

    Thanks

    Will
    1996 GMC Suburban, 6.5 TD, 4L80E, 3.73 Full floating limited slip rear end, 285/75R16E Dayton Timberline ATII's.

  2. #2
    Join Date
    Dec 2003
    Location
    SC
    Posts
    939

    Default

    Soot trap is just what diesel guys call it. Its nearly the same thing as a Catalytic converter. Or Catalyist converter or Cat I can't spell and my chemistry is so rusty I barely remember H2o is water. Anyway its a honycomb looking material that gets hot in the exhaust and reacts with the exhaust gases to react and remove some oxide or other. Something about the Nitrogen in air getting so hot in combustion and reacting and creating Nox's etc. Not sure how different it really is from a gasser CAT similar but probably slightly different. You might find a technical post on it. But CAT is used commonly in a lot of post and is too short so not sure of good search word phrase.

    It surely doesn't keep a diesel from belching black smoke or trap soot from escaping by intent. More or less it does restrict the exhaust gasses and is kinda like a trap maybe why its called a soot trap because it seems to soot up and foul over time with a very poorly running engine. Or maybe that it traps the exhaust gas to increase heat for the catalyst reaction?
    97 5spd K2500 Ext Cab short Bed ~160K miles.
    TM, 3" downpipe & 4" exhaust, remote FSD, remote oilfilter, Gauges: EGT, Boost, Fuel Pressure, B&W Gooseneck Turnover ball, Prodigy Brake Controller. Hi-Temp Hydraulic Oil Cooler Lines.

  3. #3
    Join Date
    Nov 2006
    Location
    Kelowna, BC
    Posts
    1,070

    Default

    Get rid of it. You and your truck will be happier.
    1993 HD2500- 4X4, Nv4500, rc/lb, Lots of mods, killed her. Awaiting her TT rebuild!

    2002 Camaro L36/M49- Killed In Action

    1995 HD2500 - 4X4, NV4500 rc/lb, GL4, Turbo, exhaust

    1994 HD2500- 4X4, NV4500, ec/lb

  4. #4
    Join Date
    Oct 2008
    Location
    Michigan
    Posts
    83

    Default

    Its already off of My rig. I was going to punch the inside out and put it back on but searching online they run almost 400 bucks brand new. I figure there's someone out there who might want it so I decided not to destroy it.
    The burb wasn't as loud after I pulled the cat and muffler as I thought. Will a larger pipe give me more sound or just a deeper tone? I do have noticeably better throttle response and I got an extra 2 mpg on My last tank. also I can actually hear the turbo spool now which was never audible with all that restriction.
    1996 GMC Suburban, 6.5 TD, 4L80E, 3.73 Full floating limited slip rear end, 285/75R16E Dayton Timberline ATII's.

  5. #5
    Join Date
    Feb 2000
    Location
    Montana
    Posts
    11,382

    Default

    The "cat" as used in a light-duty diesel is more accurately defined as a Diesel Oxidation Converter (DOC). The DOC is a ceramic honey-combed structure that is washcoated with a layer of catalyst materials (Platinum, Palladium and other rare-earth base metals). These catalysts chemically react with the exhaust gases to convert nitrogen oxides (NOx) into nitrogen dioxide and to oxidize (burn) hydrocarbons and particulate matter (PM = soot).

    Jim

  6. #6
    Join Date
    Nov 2006
    Location
    Kelowna, BC
    Posts
    1,070

    Default

    Going to 4" is as big as you will need. Anything bigger is kinda pointless. Big tips are fine, but if you start going with to big of pipe the whole way, the 6.5 will sound a little tinny, IMO.
    Throttle response, better mileage, and the sound of your turbo, all are a good payback for opening it up.
    1993 HD2500- 4X4, Nv4500, rc/lb, Lots of mods, killed her. Awaiting her TT rebuild!

    2002 Camaro L36/M49- Killed In Action

    1995 HD2500 - 4X4, NV4500 rc/lb, GL4, Turbo, exhaust

    1994 HD2500- 4X4, NV4500, ec/lb

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