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Duramax 6600 Welcome to the Internet's first Duramax 6600 diesel discussion forum for the LB7, LLY, LBZ, LMM, LML, LGH & L5P RPO code engines. Tips on performance, fuel economy, troubleshooting and more.

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  #31  
Old 08-10-2006, 05:13 PM
Kelly T Kelly T is offline
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Join Date: Jun 2005
Location: Marysville, OH
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Default My 05 LLY

Updated - over 25,000 miles now. 19 MPG seems to be working. Bone stock. 2500 HD CC.

http://home.columbus.rr.com/vfrket/Diesel/Diesel.xls

Note my calculated Miles Per Hour (miles for the tank divided by elapsed time (hours) from the from the DIC) to the far right. BTW, I still like my spreadsheet. There are few rows of data where I had to add a couple tanks together.

Kelly
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  #32  
Old 08-12-2006, 12:44 PM
Uncle Wally Uncle Wally is offline
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Default MPG's

John,

I agree with you. I never thought I would see it either.

Did you have the AC on? I've found that makes a pretty significant difference. Although I will have to admit, it's kind of hard to not run the AC when it's 80+ and humid. Ventshades work pretty good with the windows cracked and the vent on.

I also had the tires inflated to max rating in the rear due to the trailer towing.

I want to try running 235/85's and see if it makes a difference. I have a set off my 94 that's begging to be installed. I just need to use up the ones that are on it now. Just wish I didn't have to machine the Alcoa's to get em to fit.

I'm going to be making a run to Eagle River WI here soon. Hopefully I can back up that 20+ number.

Waldo
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  #33  
Old 08-12-2006, 01:50 PM
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rob from bc canada rob from bc canada is offline
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Kelly T:


I looked at you spreadsheet, and you seem to have a period where your were getting 16-17, and then back up near 19 average. Are these all long trip flatland driving - your average speed per engine hour is about same as mine, or maybe a bit higher.

That is pretty impressive mileage - what did you do different?

Bet I can do with careful driving over a tankful is about 18 US mpg.

However mine is a K3500 = 7000 lbs empty and 4wd, is your perhap 2wd, and less weight, which could make a difference?
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  #34  
Old 08-12-2006, 06:09 PM
Kelly T Kelly T is offline
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Best I can attribute it to is crappy gas in the winter, bad road conditions (some time in 4wd just to commute to work), and maybe some more city driving. My 2500 HD is a 4wd. I live in central Ohio so now and then we get some winter. At the time I was disappointed too.

Behavior-wise - biggest thing is trying not to be hard on the gas in stop/go traffice trying to get out of Columbus when trying to reach the highway. That seems to be the killer on calc and indicated MPG quickest. Sometimes when sitting in traffic (red light, grid-lock) I'll shift to neutral (automatic) so the truck isn't pushing against the brakes. My driving has some hills on it, but not a lot.

I have no bed cover either. I'd like a "Undercover" and an Edge Juice w/Attitude (or maybe a visit to John Kennedy) to see how they play out from an economy viewpoint (and some pep when desired). And then a 4" exhaust (full). I don't do anything wild with air pressure - keep it at the top of the normal limit (50 psi). Not hauling a load too often - when I am it is an morotcycle or 4 wheeler and my milage gets better as it keeps air off the tailgate (or seems too).

2 cents,
Kelly
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  #35  
Old 08-14-2006, 11:31 AM
AlbertaDiesel AlbertaDiesel is offline
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Default Mpg

Hi guys
New here, love the forum so far.
I recently bought an '06 Chev Crew 1 ton SRW LB 4x4 LBZ. My first hand calculation of mileage running empty at average 70mph was 18.32 US MPG. My next was a long trip pulling my 26 foot holiday trailer (which my wife likes to load to the nuts) again at average 70 mph and I hand calculated 10.41 US MPG. Not quite as good as my old '93 Dodge Cummins, but then she couldn't pull that rig at 70 mph all the way, either. I am a mileage buff, too, so I will likely post more results as time passes. With fuel prices skyrocketing lately, good mileage is a big concern. I think a 2 mpg increase would be worth it to justify a "mod".
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  #36  
Old 08-14-2006, 03:32 PM
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rob from bc canada rob from bc canada is offline
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Quote:
Originally Posted by Kennedy
I'm waiting for more feedback from my testers. I started another tester at the Rendezvous.
...
I expect 19-20+ mpg from a single rear wheel truck driven at approx 60mph. My MPG drops at 70, but seems to drop less with tuning.

This "Economy Tune" for sale yet? What is involved and how much?

Need any Canadian testers???

I've got about 17,000 km on my truck now, and I've kept records for every fillup so far.
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  #37  
Old 08-14-2006, 08:59 PM
Kennedy Kennedy is offline
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The tunes are available any time. There is a review by Todd Smith on this site.
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  #38  
Old 08-17-2006, 10:16 AM
sb359 sb359 is offline
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Default mileage

best i've done is 20.1 mpg empty and 15 mpg pulling a 6800lb travel trailer
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  #39  
Old 09-12-2006, 11:14 AM
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ToddMeister ToddMeister is offline
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Thumbs up Long trip update

Recently took a long trip to the East Coast over Labor Day holiday about 1500 miles, 90% turnpike/expressway driving 60-70 mph, 10% city driving. Truck had 4 passengers, box full of luggage/cargo. I averaged 19.8 mpg hand calculated, DIC said 19.7 mpg average. I'm am running Kennedy's economy tune from the Rendezvous. And also running LT265 tires, speedo is accurate (verified with GPS). Had lots of driving in the rain and wind!!!!
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  #40  
Old 09-12-2006, 12:18 PM
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rob from bc canada rob from bc canada is offline
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This "economy tune" sounds real good.

I think mine would have done about 17 -17.5 driving as you have described.

If true, at $3.00 per Gallon, you saved about $30 on this trip, and if you keep the truck for 200k you might save about $4000.

From what I saw on Kennedy's site, you need a spare ECM to load his tunes.

What was the procedure for you, and what did the whole thing cost???
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