Catalytic or no catalytic?

[Riverholic]

I am going to do an exhaust (kennedy's) on my truck and I am wondering if it would be to my benefit to remove the catalytic converter. My exhaust guy told me to order the 49-state pipe to replace the cat. I would only remove it if it could be put back in easily in case california starts smog testing diesels. Would it void my warranty? Also would the missing cat cause problems for the computer? What gains if any would I see with no cat?

[SoCalDMAX]

All very good questions.

1. Instead of ordering the 49 state model, ask Kennedy if he might have one that he can sell you, much cheaper and could ship with the exhaust.

2. Keep the old one, I'm sure we're gonna get inspected/smogged in the future.

3. Don't know what gains will be made. I'm about to find out here in a 1/2 hr. It's very easy to remove/install. I would imagine judging from the way it's constructed that it does mess up flow somewhat, how much is a guess.

4. All we'll really gain is to be on a level field with the 49 state trucks.

Good luck, I'm sure you'll be very happy with the new exhaust!

Regards, Steve

[SoCalDMAX]

OK, spent a coupla hrs wrestling with the pipe. The jury is still out if it's desirable to remove or not.

After removing the cat, seems as though the turbo lag is longer. Maybe my imagination. But the exhaust is defintely a little louder outside, no real change inside. The part I don't like is when using the power plug on max and propane on, the truck emits a noticeable puff of black smoke (2-3ft dia.) at launch before spool up. I used to get a very light hazy smoke, really only visible at night in following headlights.

If someone else wants to do this removal, here are some tips to make it easier.

1. Remove vee clamp at front below turbo with 10mm deep socket.

2. Loosen, don't remove, 4 15mm nuts aft of cat.

3. Remove 13mm bolt at rear of tranny holding muffler hanger assy below cat. Need short swivel socket to start, box end ratchet wrench to finish.

4. Remove 13mm nut from stud on side of tranny for same hanger. Regular socket works here.

5. Slide hanger off from pipe and get it out of way.

6. Unbolt and remove 4 15mm nuts from rear of cat pipe.

7. Drop front of pipe down and rotate pipe while pulling fwd. Cat will wedge between torsion bar and edge of Allison tranny pan. Just push it out, it'll go.

8. Installation is reverse, start the 4 rear nuts first, tighten down the vee clamp, then tighten the 4 rear nuts. Install the hanger last. Much easier to deal with the straight pipe due to more clearance than cat.


I'll run around more with it like this for a while and give an update when I've got conclusive proof one way or the other. My initial impression is that perhaps there's some ECM programming that is different for the CA versions and I'm actually losing a little power... doesn't make sense, but we'll see. I really don't like the smoke, makes me feel like I'm wasting fuel... ;)

Regards, Steve

[wangotango]

great report, thanks

but jeez...get some sleep will ya'

w/t

[ndamico]

Can someone please post a picture of the cat from a 2002 Dmax. I'm trying to find out if my 02 Dmax has one or not...

thanks

[Tader Jack]

You may want to check to see what the law is regarding this. I know I had some trouble several years ago on a suv. I believe it may be a federal law. It went like you couldn't remove or change the catalytic until you had at least 50K miles or it was in a wreck. Don't know if it varies from state to state or whatever, but it is not legal to remove it.

I learned the hard way. Now your state may not have vehicle inspections, but I believe the law is still there. Most exhaust shops pretty well know that. I'm not sure how it applies to diesels, but it might be wise to investigate first and let us all know.


Jack Schultz, McKean, PA
jackschultz@adelphia.net

http://photos.yahoo.com/bc/jack_schultz2001/rlst


2001 Chevy Silverado, 4-WD, 2500HD, Crew Cab, Short Box
LT Trim, Black Onyx w/ Tan Leather
Beltronics 980 Radar Detector • Blinder M-10 Plus Laser Radar Jammer
4 Rockford Fosgate FRC2206 Full Range Speakers • Husky Rubber Floor Mats
Lund Interceptor Wind Deflector • J&J Stainless Steel Tube Grill
Putco Stainless Steel Bed Rails • Access Roll-up Tonneau Cover • Pendaliner SR Bed Liner
DTA Stainless Running Boards and Mud Flaps • VentShades • Pop-Lok Rear Tailgate Lock
Lucerix Remote Control X-Mount Camper Mirrors • Unity Dual Door-mount Halogen Spotlights
Air-Lift Super Duty Ride Control w/ Dual Controller & Onboard Compressor •
Tekonsha Voyager Trailer Brake Controller • Uniden 510XL PRO CB Radio, Wilson Antenna
Kennedy Diesel Headlight Harness with 4 Lamp Mode • PIAA Platinum Super White Headlight Bulbs
Amsoil 2-Stage Air Filter • FPPF Total Power Diesel Fuel Treatment • FPPF 8+ Cetane Improver
Amsoil 15W-40 Synthetic HD Diesel & Marine Engine Oil • Amsoil Series 2000 75W-90 Synthetic Gear Lube (GL-5

[ 05-07-2002: Message edited by: Tader Jack ]</p>

[DmaxMaverick]

ndamico

I don't have one ('01), but have seen them on the new trucks around here, so no pic's from me.

Your '02 CA model should have one. Look at the exhaust system. If there is anything between the turbo downpipe and huge muffler (besides the pipe), you have a cat. They are pretty big, so you shouldn't miss it. The exhaust system is simple. Turbo, downpipe, tubing, [cat], muffler, tubing, outlet. If anything else is in the picture, that should answer your question. There should also be an emissions description sticker under the hood, near the radiator that says "Catalyst".

[mackin]

ndamico,

These are socaldmax's pics.Our friendly moderator ;)


http://www.pbase.com/sfrakes/2002_silverado

Go to Gibbs exhaust... Check it out, the so called CAT is there in front of cross member..Only 02 's in Ca. got them..Thank goodness........as to removal, yes it would be lawful to tamper with......IMHO........Out east the will not inspect emissions unless you have all the factory installed emission equipment........I'm exempt 11,000 GVW WOO......HOOOOO.........How often do the inspect out there? Here it is 2 years.......Most guy's with cars take them off and reinstall before inspection..Due I need to discloser here......
MAC :D :D

[ 05-07-2002: Message edited by: mackin ]</p>

[ndamico]

thanks mackin! i have a bit of time before i'm ready to get exhaust..just seems strange to have it on a diesel. gotta sell my 97 1/2 ton first! anyone need a sweet 1/2 ton with a 6" lift and 35's? it has TV, DVD, and Navigation too!

thanks for all the advice...just figuers, friggin Kalifornia...someday i'll get outta this state!

[stretch]

Here in NJ, the first thing they check for is a catalytic convertor. They run around your vehicle with mirrors on poles so they don't have to bend down and look (saves on workman's comp). If its supposed to be there and its not. instant failure - bye bye. I also heard of roadside inspections where they harass if not impound vehicles for emmission reasons. Definetly retain and/or have the provision for the cat. :eek: