Duramax LBZ & LMM – WHAT’S THE DIFFERENCE? by Duramaxtuner.COM

Duramax LBZ & LMM – WHAT’S THE DIFFERENCE? by Duramaxtuner.COM

(rock music) – Hi, I’m Nick with duramaxtuner.com, and I have Bob Petersen with me today, and we are going to tackle the question of the difference between LMM’s and LBZ’s on today’s DT Q&A. So, 2007-and-a-half, there was a switch over. Tell me what happened, Bob. – The big switch is obviously body style that you can visually see, so the big question we ask, is it a new body style or old, their half year? The other huge introduction is emissions, so you’re gonna have a DPF on the 07-and-a-half, new body style LMM. – Yeah, so like you said, the truck has a new body style, that is the bumper style that
you see in the background. It’s got a DPF on it, and it’s got an LMM motor. – Correct. – We got a pretty solid upgrade, though. Five horsepower. – Yup, yeah. Lot of similarities in
the actual hard parts, other than the addition to the DPF. – Yeah, so I mean, foundationally, the engine is almost unchanged. They take the same power, they have the same
strength, same weaknesses aside from the DPF. There are a couple little things that changed, and we’ll just go over those, and they’re mostly around
emissions equipment. In front of me here, I have the EGR Cooler from an LBZ truck. So, this is on all 2006 trucks. You can see the shape is round. On an LMM truck, so 2007-and-a-half, you have a square-shaped EGR Cooler, and it has a bigger opening on this end. It’s a subtle difference, but the cooler capacity is improved, so the chance of those failures is less. Also, you have the intake piece from an LMM, and the difference that you can see here is that, on an LMM, you
have a four-bolt flange after the intake heater, and there’s a intake airflow valve there to regulate the amount of
airflow allowed into the engine. That’s to control exhaust gas temperatures to initiate the light off of the DPF system. So, if you show them yours, over there. Yeah, and that just connects right to the inner cooler from there, so little difference, and then, also on the LMM, you have a coolant hose that goes off the oil cooler, and we’ll cut to a picture of that. – [Bob] Another difference we have between the two is the ECM. Physically, the case is identical. You wouldn’t be able to know the difference between the two by– – [Nick] They look identical? – By not knowing the
serial numbers on ’em. Obviously, the internals are
gonna be a little different. The LMM has the control of the emissions in the new style.
– Yeah, so you have the code for the DPF control. Yeah, they’re both 80C16, they’re both based on
the same architecture, five position switching
for both of them, right? – Correct, yep, same install, same pins, same location on the trucks. – Yeah. Power-wise? – Same. Working with a six-speed Allison behind both of them, power-wise and the holding.
– ‘Kay, so you can build the trans. – Yep. Holding capability in the stock form is the same, as well as the belt form. The motor limitations are gonna
be about the same, as well. – So a 530 horsepower range is what we’re looking
for with both trucks. – On a stock turbo, yes.
– On a stock turbo. So, really, if you’re building a truck for
performance application… – Yeah.
– It’s a wash. – Yep, if you want the
new body style or old, there if you want them,
that’s with emissions or not. – So, from there to the fuel system, we have the injector difference. The LBZ was a seven hole, 158-degree spray pattern for injector. For emissions purposes,
they switched it up a little bit, to– – Six hole on the OMEM, 159-degree. – Okay, so you’ll see
the switch over, right, if you’re going to the big injector. – Yeah, I believe the seven hole injector is used for anything below 100%, and they’ll
use the six hole for above. They are pretty interchangeable. The bodies are almost identical, the connector’s a little different. They can be interchanged–
– They can be made to work. They’re very similar trucks. The emissions equipment is a bit of a frustration, the LMM is the first year for the
emissions equipment. For the DPF, I should say, not the EGR. The DPF system is not as capable as the emissions system on the LML trucks, so they are a little
more prone to failure. They don’t have the ninth
injector, so you do have the system potentially
washing out the rings, getting extra diesel fuel in the oil, so it requires maintenance. – Correct, yeah, and the big thing is mileage, too. You know, if you’re looking to build a compliant truck, or get power out of a compliant truck, just be mindful of the mileage and the life it’s had, so obviously, these are designed to fail at some point, like you said, and they become overactive and they can hurt the truck, so if you’re looking at a 200,000-mile truck, if it’s never had emissions
equipment serviced or replaced, you’re probably
on the last leg of it. – Yeah, or hasn’t been
well-maintained anyway. An LMM farm truck versus
an LBZ farm truck. You know which one I want. (chuckles)
– Yep. – Cool. So, that wraps it up,
pretty straightforward. I’m Nick, this is Bob.
– I’m Bob.

About the Author: Michael Flood


  1. Wasn't the LBZ rated at 360hp 650lb/ft and the LMM 365hp and 660b/ft?

    You said the power is the same between the two. Is that GM just playing the numbers game with ratings or am I wrong?

  2. Will LMM nozzles fit and work on a LBZ injector? I found a great deal on some 100% LMM nozzles if they will work on LBZ.

  3. I have an 08 lmm duramax, dually long flat bed, gooseneck, pulling 5th wheel camper 15k pounds, I bought the truck with 200k miles, put about 20k on it in 2 years, having all sorts of problems now, but I have narrowed it down to needing to pull the injectors and have them serviced , and pull the cpm pump possibley and put in a rebuilt cpm pump, on this video you talk about the dpf system and how it might could wash out the piston rings with blowby, jeez, and dilute the motor oil in the crank case,…..jeez, how do I check that, do I have the oil in the crank case checked like viscosity or something like that ., ….jeez, I like this truck because it is a western hauler bed, and perfect for us to go camping, but it has stranded us several times, when i have tried to maintain like 60mph on up hill grades over time, then it has powered down, like I said i have found the problem with that, I had a shop guy get in with his computer while I towed the fifth wheel , and after about the usual 30 minutes of heaving towing, his codes found the problem, I have an air dog, etc, everything else is good, just how do i find out if my oil is getting contaminated, thanks

  4. ive got an 06 lbz. I got on it a little hard then it puffed some oil smoke . went to restart it 10 minutes later and it started then stalled. Is there an O ring that tends to go bad that could cause me to have no oil pressure?

  5. Dead serious delete the bull crap emission sp you actually get what u pay all that money for, I had a Cummins dually deleted and I can get sideways in it. My boss has one stock and can barely make it out of the damn parking lot plus he get 8 or 10 mpg while I get 20 to 24

  6. LLY is very good. Stronger pistons. Easy-to-rectify turbo inlet ducting (<$150.), and EGR cooler. No DPF. Best performing VVT turnocharger. Basic design is what counts.

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