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Duramax 6600 Discussion Forum for the Duramax 6600 Diesel Engine, including the LB7, LLY, LBZ & LMM engine specific topics.

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Old 04-11-2007, 10:20 PM
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I visited the local GMC dealer today and discussed the first LMM 2500HD crew cab they sold a week or so ago. I had hoped to shoot some photos of that one, but missed it. However, I did get some shots today of an LMM equipped 3500HD chassis cab...

The owner of the LMM 2500 reported that his first tank of fuel produced 17 mpg while running at Interstate speed across Montana. This owner has owned a number of Duramax powered trucks prior to this one, his LB7's would produce close to 20 on the same trip, and his last Duramax (a 2005 LLY) struggled to produce 15. So, he's happy with the LMM... so far...

Jim
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Old 04-12-2007, 04:42 PM
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Quote:
Originally Posted by More Power
I visited the local GMC dealer today and discussed the first LMM 2500HD crew cab they sold a week or so ago. I had hoped to shoot some photos of that one, but missed it. However, I did get some shots today of an LMM equipped 3500HD chassis cab...

The owner of the LMM 2500 reported that his first tank of fuel produced 17 mpg while running at Interstate speed across Montana. This owner has owned a number of Duramax powered trucks prior to this one, his LB7's would produce close to 20 on the same trip, and his last Duramax (a 2005 LLY) struggled to produce 15. So, he's happy with the LMM... so far...

Jim
Keep us/me posted I ordered the new body sierra LMM 3500 SRW SLT 4X4 long bed and hope to get it by the end of May.
Anything has to be better than the 6.0 disaster I had.
I know it is early reports but "Thanks for the info".
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Old 04-13-2007, 11:58 AM
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Here's a shot of the 2007 LMM equipped chassis cab.



GVW is reported as being 12K. This one is equipped with dual fuel tanks and 4WD. The exhaust system is equipped with a DOC (Diesel Oxidation Converter) and DPF (Diesel Particulate Filter), but no muffler. Also, the air mixing exhaust tip is a downturn tip ahead of the rear axle.



The engine looks very much like the outgoing LBZ, except there is now a throttle valve in the intake plenum, upstream of the intake air heater.

Jim
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Old 04-14-2007, 04:35 AM
DieselMonk DieselMonk is offline
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[QUOTE=The engine looks very much like the outgoing LBZ, except there is now a throttle valve in the intake plenum, upstream of the intake air heater.

Jim[/QUOTE]

I am trying to compare it to my late production LBZ (12/06). Could you make either a better picture or circle that "throttle valve" please? Ran in the garage this morning and took couple of pictures of my engine compartment to compare it to your pic.
The only thing that is missing on mine is that silver shielded cable thats fastened along the firewall behind the plastic 6.6L cover.
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Old 04-14-2007, 09:10 PM
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GM calls it an "Air Intake Valve", which is controlled by the ECM. The valve is activated during DOC/DPF regeneration, EGR operation and "rich idle".


Jim
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Old 04-17-2007, 10:00 PM
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What did you think of that downturn pipe just ahead of the rear differential?

The C-4500/ C-5500 trucks are the same way. Looks kind of scary!
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Old 04-18-2007, 12:47 AM
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Quote:
Originally Posted by Duramaster
What did you think of that downturn pipe just ahead of the rear differential?

The C-4500/ C-5500 trucks are the same way. Looks kind of scary!
I think GM would rather peel up road stripes than torch pedestrians.....If it ever comes to that.
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Old 04-18-2007, 02:44 PM
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Quote:
What did you think of that downturn pipe just ahead of the rear differential?

The C-4500/ C-5500 trucks are the same way. Looks kind of scary!
The pickups use an exhaust tip that exits under the right rear of the rear bumper. Only the chassis cabs (& medium-duty trucks apparently) get the exhaust tip ahead of the rear axle.

I'll have close-up pics of all this in an upcoming article, but the tip exit looks way too close to the right rear shock....

Jim
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Old 04-24-2007, 06:46 PM
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DIC average for dealer delivery was 17.4. My LLY was about the same when I first picked it up.
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Old 05-04-2007, 11:47 PM
jsracing6 jsracing6 is offline
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i get around 17 empty on highway and 7-9 towing 7000# 28' enclosed car trailer
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