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07 LBZ - questions about removing the kitty

Odlaw

Odlaw

Redneck
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577
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Location
Deep in the woods - near Waldo, FL
OK, after searching around on the web and finding mixed results...and didn't find anything on TTS, I thought I should ask here; on an LBZ d-max are there any computer or sensor related issues to removing the kitty? I want the thing gone, but don't have the $$ right now to just replace the entire exhaust. From what I've read there are no o2 sensors before or after the kitty on the LBZ's (I'll look tomorrow but in the mean time, thought I'd check here).

Also, is it true that the LBZ's don't have a traditional ceramic kitty?


Thanks
Smitty
 
You have a spun metal kitty that really isn't worth the time to yank it off. They simply are not restrictive like the ceramic kitty's were in the past. Your time is better spent blocking the EGR because you will notice that change...

What in the computer would care if the kitty was there or not? - Nothing. The trouble comes from the DPF stuff on LMM's...
 
The cat provides the backpressure so that the EGR can force exhaust gasses back into the intake. SOME trucks will throw EGR codes with the cat off because the flow will be insufficient... mine never did and chances are likely that yours won't either.

About the only benefit you'll see with the cat off is around 200* lower EGT's and more noise, especially at WOT. It won't do anything power/mpg/performance wise. JMO, but if you do take it off, do it right and get a cat delete pipe. Don't hack up the cat or factory pipe just in case you ever have to put it back on.
 
ok, thanks. Yeah, I've already blocked the egr. I have several sticks of pipe...well, emt in 3.5" and 4" and some adapters that I should be able to make work.

Sounds like I'm gonna be disappointed in the outcome...oh well, only one way to find out ;) ...hoping to get a little more whistle out of her. I've heard two sides to the kittys on these trucks. If it helps build back pressure then it must be some-what restrictive maybe? Some say removing it increases whistle from the turbo...some say not.

Thanks again guys
Smitty
 
Certain rpms have a nice throaty rumble and it's wicked loud at WOT, but it sounds more like a pissed off vacuum with no cat because of the turbo. At idle, all you will hear is a hiss like air pressure escaping from a leaky valve. It actually sounds pretty good though.
 
That was my favorite mod to my LBZ (besides tuning ofcourse), makes them sound a lot better than with the stock system in place.
 
OK, for whatever reason the cat on my 07 lbz is a typical, ceramic type...and it's OEM - has not been replaced. This is NOT a California truck either. It was clogged pretty good...so, wanting to minimize the amount of time spent on fabricating, I removed the down pipe and cat and put em on my welding table. On the top side of the cat I cut a large access hole, busted up enough of the ceramic to get it to come out, dumped everything out and welded in a 3.5" diameter pipe straight through the center of the cat, welded the access panel back on, reinstalled down pipe and cat..the whole project took less than three hours...and thirty minutes of that time was trying to get the center exhaust support bracket (that bolts to the ally) bolts started - LOL. I took some pix and as soon as I figure out how to put em this post I'll do it.

Truck sounds sweet! Nice hiss and very slight whistle (not annoying like a totally open exhaust) - I still have the factory muffler. I can feel the difference and the turbo spools noticeablyquicker and spools down really slow like a free flowing exhaust should...and when I shut the truck off you can walk back and hear the turbo winding down for at least 12-15 seconds.
kitty guts.jpggutted pipe welded in place.jpgall buttoned up.jpg
 
I never had an issue with removing mine either. I thought it sounded damn good with a 4" system.

Get you a good CAI and that'll really make the turbo louder.
 
Unit453 said:
I never had an issue with removing mine either. I thought it sounded damn good with a 4" system.

Get you a good CAI and that'll really make the turbo louder.
Click to expand...

Hey Nick, yeah, eventually I'll be installing a 4 or 5 inch exhaust...but in the mean time this was a nice compromise. Some time ago I was looking into a CAI and other than hearing the turbo, everything I read basically said the 07 intake/filter was the bomb...once you remove the restrictive "tornado" fins from the filter housing there wasn't anything gained swapping it out...the stock setup is supposed to flow enough air for 700 hp (IIRC).

What is really weird about this cat is everything I've read here and elsewhere has basically said "nothing to be gained, muffler is more restrictive than cat, cat is metal type which flows nice and is not prone to stopping up" etc. etc... well, obviously that's not the case...wonder if some trucks came with different cats or if there is just a lot of misinformation out there.

I was just out in my shop putting up tools and cleaning up and was explaining to my 14 year son how a cat works and looking through the big chunks with my shop lights in the background I could see a lot of blocked holes. Looking on the bench where I busted it up to get it out there were a bunch of little black "sticks" about 1/4 to 3/8 of and inch long laying all over the place...it was the contents of the webbing of the cat!

I cranked the truck to move it out of the shop and he said "dad, your truck sounds awesome" - lol we both stood at the back of the truck listening to it idle...that's what I call a male bonding moment. :thumbsup:

Smitty
 
Mad Maxx said:
Good Choice in Deleting it, and nice Work on the Cat to "Stay Under the Radar".
Click to expand...

Thanks, and in case anybody is wondering, the reason I welded in a straight through pipe was to retain the thick insulation that is attached to the inside of the cat - it'll still pass a knock test...not that it matters in florida. You can't see it in the pix but the holes on either end of the cat are not aligned so the pipe had to be cut at an angle and obviously I couldn't weld all the way around it but it was a nice snug fit...I was hoping to keep the insulation from disintegrating a clogging up the muffler(the insulation is very dense and appears to be robust in construction except where I gouged it) ...so, the pipe itself is not totally "sealed" but the access hole is.
 
Looks good. Nice job. I am anxious to find out if you gain or lose fuel mileage, as other members who removed the cat have lost fuel mileage. As Bill stated, you will notice a drop in EGT's.
 
If you get tired of teh jet engine exhaust, come on down and I can set you up pretty cheap with an EFILIVE tune. The one I built up a few weeks back was IMPRESSIVE for a stock truck with just an exhaust, TRANSGO JR, and tune(would break the tires loose in 3rd).
 
I would have never guessed that you would lose fuel mileage by removing the cat...I wonder how/why that happens...I mean, I understand that the first tank or two the mileage will drop (as it does with any mods...like my old 6.5 - mpg went in crapper the tank after I added the boost gauge - lol). If it still drops after I get done playing with it, that is going to suck.
 
THEFERMANATOR said:
If you get tired of teh jet engine exhaust, come on down and I can set you up pretty cheap with an EFILIVE tune. The one I built up a few weeks back was IMPRESSIVE for a stock truck with just an exhaust, TRANSGO JR, and tune(would break the tires loose in 3rd).
Click to expand...


LOL 3rd gear? that is impressive. I'm sure I'm going to take you up on your offer...might be a bit, gotta get my funds in order.
 
RI Chevy Silveradoman said:
Looks good. Nice job. I am anxious to find out if you gain or lose fuel mileage, as other members who removed the cat have lost fuel mileage. As Bill stated, you will notice a drop in EGT's.
Click to expand...

First tank of fuel (playing with long pedal on the right just to hear it whistle) I got 16.5 mpg which I expected(normally average 18.7 running back and forth to work). It was also in the low 20's a couple of mornings so a good bit more "idling/warm up time". Second tank, was getting around 18 and then had to tow a trailer with a self contained, 3 point hitch backhoe - probably 3k pounds plus 1k trailer. Got 17.3 mpg on that tank. So far, I haven't seen any loss in economy...and really don't see how that could happen...but hey, I aint the sharpest tool in the tool shed, maybe somebody could 'spain it to me.
 
Well I cant explain why you would get lower MPG but I am itching to get an exhaust set up on my truck. I just doubt I will get 18-20mpg just tooling around still, I can barely keep myself from watching smoke puff as it is....
 
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