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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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  #21  
Old 06-02-2006, 11:27 AM
Kennedy Kennedy is offline
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Default

Just FYI, the changes made should not have had a big impact on DIC readings, in fact, should be none at all...
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2002 Chev K2500HD D/A CC Long LT 11.77@ 124mph at 7700# fuel only-e.t. needs help
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2007 Chev K2500 Classic EC Short LT (Sold)
2012 GMC K3500SRW D/A CC Long LTZ Happy Birthday to me! Built 1 working day after my birthday and delivered 7 days later.
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  #22  
Old 06-02-2006, 02:15 PM
JoeyD JoeyD is offline
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Easy driving is key to higher milage. I have not done any highway only trips in my Express but I average 17.5 all the time. I keep speed under 70 on the highway and take off easy in town.
I would think 20 is possible on the highway is you keep it under 70. With the 6spd ally you guys in the 06's run maybe better
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  #23  
Old 06-12-2006, 11:22 PM
REDTRUCK05 REDTRUCK05 is offline
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Join Date: Aug 2005
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Default new tunes

Quote:
Originally Posted by Kennedy
I can't get 20's at 70 mph, but at 60-ish mph I can run solidly into the 20's. It will be interesting to see what Uncle Wally reports as I just sent him a tune for his dually. The DIC shows encouraging results so far, just need to hand check to verify...
Let us all know how ur new tunes do. Why is your 05 for sale?
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  #24  
Old 06-29-2006, 10:12 PM
REDTRUCK05 REDTRUCK05 is offline
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Default Mpg

Are you happy getting 14-15 under normal driving conditions? U say your best milage is at 50-60 mph? That makes sense, its logic. People just dont drive that slow on the interstate in Mpls. I like to drive the speed limit 70 mph. If I do this I get between 9 and 11 mpg, pulling 5600 lbs. If I treat the pedal " like an egg shell" unloaded I can get 14 - 15 at 70 mph. If i slow it down to 60 mph ( only when I have to ) I can get 16 - 17 mpg. Do you guys really think these numbers are ok? I think not...
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2007 GMC 2500 crew cab LBZ
6.6L duramax
Roof markers and XM radio
Rhino liner
Plat series nurf bars
Putco bed rails
Truxedo bed cover
edge juice W/ monitor temp uninstalled.
Hypertech stage 3
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  #25  
Old 06-30-2006, 06:05 AM
Kennedy Kennedy is offline
Long Distance Crew Chief for BMDMAX
 
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Quote:
Originally Posted by REDTRUCK05
Let us all know how ur new tunes do. Why is your 05 for sale?
I'm waiting for more feedback from my testers. I started another tester at the Rendezvous.

I'm not really pressing to sell my 2005, but I put it up in anticipation of acquiring a 2006 LBZ.

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.
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Kennedy Diesel-owner
More than just a salesman-I use and test the products that I sell on a daily basis!
Superflow Lie Detector in house
2002 Chev K2500HD D/A CC Long LT 11.77@ 124mph at 7700# fuel only-e.t. needs help
2005 Chev K3500SRW D/A CC Long LT(SOLD)
2007 Chev K2500 Classic EC Short LT (Sold)
2012 GMC K3500SRW D/A CC Long LTZ Happy Birthday to me! Built 1 working day after my birthday and delivered 7 days later.
2016 GMC K3500SRW D/A CC short LTZ

Custom tuning in house using EFI Live tuning software!
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  #26  
Old 07-01-2006, 05:21 AM
ToddMeister's Avatar
ToddMeister ToddMeister is offline
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Thumbs up

I'm the economy tune tester from the Rendezvous John was talking about above. Took a long trip this past week and averaged 20 mpg with expressway 70-75 mph, some highway at 55-60 mph, and a bit of city driving mixed in. Outside temps were 75-80 degrees.

Truck is a 2005 GMC Crew Cab 4x4 Duramax LLY/Allison. Presently 13,000 miles on the truck.

I want to take a trip of primarily 55-60mph highway driving to see what the tune is capable of.

I am also running Michelin LTX M/S 265-75-16 tires, which will lower your mileage a tad bit from the stock 245's.

At 70-75 mph EGT runs 600-650 degrees, and boost is about 3.5 lbs (on flat roads). At 55-60 mph EGT is 550-600 degrees and boost is less than 2 lbs. These readings are taken pre-turbo.

More to come....

Todd
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  #27  
Old 07-05-2006, 04:33 PM
Uncle Wally Uncle Wally is offline
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Default Mileage Update

John - thanks for the reminder. I'm still out of state so there is more to come.

Initial reports thus far:

I weighed or entire rig at the local feed lot as we were leaving: 20500 lbs.

1st tank w/ DIC (no hand calcs at this time) - 13.6 mpg (the wife drove)
2nd tank w/ DIC - 15.8 mpg (I drove)
3rd tank w/DIC - 14.5 mpg (we both drove) This tank also had some some really steep grade coming through Wheeling, EV and then into PA south of Pittsburgh (all hills).

To come:
Hand calcs to compare against DIC (although I did notice less of a discrepancy with the 'fuel used' portion of the DIC).
Empty tank mileage with only me driving
Complete rundown of performance and mileage when I get back home

Just a quick note. Thanks.

Waldo
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  #28  
Old 08-08-2006, 11:04 PM
Uncle Wally Uncle Wally is offline
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Default The results are in

OK. Sorry for the wait. Taking 3 weeks off makes for alot of catching up to do.

Hand calcs are as follows:
Tank #1 - 13.55 mpg - DIC showed 13.6
Tank #2 - 13.65 mpg - DIC showed 15.8
Tank #3 - 12.84 mpg - DIC showed 14.5
Tank #4 - 22.36 mpg - DIC showed 23.6
Tank #5 - 16.16 mpg - DIC showed 18.3
Tank #6 - 13.15 mpg - DIC showed 13.9
Tank #7 - 12.29 mog - DIC showed 13.3
Tank #8 - 11.58 mpg - DIC showed 12.2
Tank #9 - 12.04 mpg - DIC showed 13.1

Again - I fill the truck the same way every time: fuel is at the lip and almost ready to spill out with the truck sitting as level as possible - engine not running.

I compared these figures to hand calcs from date of purchase. They are as follows:

Bone Stock - average of 13.91 mpg over ~10k

With JK's exhaust, Uni Filter and Mega filter upgrades - average of 13.72 over ~7k

Add EFI Live to above (only EGR fooled with - no added fuel or timing) - average of 15.9 over ~3k

Add JK's timing tune to above - average of 14.9 over ~5k (this is skewed as a majority of this is towing our horse trailer - only about 1500 miles without the trailer)

The shining star thus far: I hand calced a tank of fuel at 22.36 on a trip from Pittsburgh to Baltimore and back. This was my one chance to use an entire tank without my wife's heavy footed influence (which ever peddle she has her foot on, it goes to the floor). I only stopped once and that was to pull into my buddies driveway. I drove like a grandpa (no offense intended) and treated the throttle like an egg, never going above 55 mph, and coasting to stop signs and lights whenever possible. I know everyone doesn't drive this way normally, but I wanted to know what the truck was capable of. I usually drive this way when I just filled up the tank and am pissed about how much it just cost me. After a few hours, I'm back to my normal style that yields about 18.5-19.5 on the DIC. I usually get impatient with drivers that shouldn't be on the road, so there are a few full throttle runs and the occasional 80+ mph flights. With that said, I'm tickled to death that a 4dr dually can get this kind of mileage and have the power to play around every now and again.

Had I to do it over again, I would have done the same mods within the first 100 miles of ownership, and I still have a couple to go as of yet.

I keep some pretty decent records, so I would expect an update by the end of summer.

Waldo
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05 K3500 D/A Crew - Sport Red and sexy! JK exhaust and filtration, guages and EFI Live. What a blast!

71 K20 awaiting Cummins 12v swaps

For Sale: Deep Sump Trans Pan for a 4L80E
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  #29  
Old 08-09-2006, 07:37 PM
Albee Albee is offline
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Join Date: Apr 2002
Location: Cheyenne, Wy
Posts: 105
Default I wanna play this too

I had a 02 LB7 2500HD W/Allison. Took a trip back to Missouri from Wyoming. From Cheyenne to Lincoln Ne. the truck got 20.7 MPG (hand calculated) running 75 the whole way. On the way back to Wy. the truck got 18.3. Here we go with uphill and downhill and wind. The wind always blows here and alway from West to east. I was very happy. The truck got consistent 15.5 to 16.5 running my day to day routes in town during the summer months. During the winter months it would get right at 14-15 MPG.

The new 06 LLY 3500 Dually, Allison does not do as well. I have not taken the trip back east since had this truck. But running my standard routes here in town the truck gets 13-14 in the summer and in the winter it drops to 12. I now pull a 18K fifth wheel with the truck and pull at 60-65 MPH average. Pull 175 miles to camp over three passes going as high as 9800ft. elevation and the average for the trip is 9.3 there and back. I use much more going than coming home. These were all bone stock truck numbers. I have now added 4" catback exhaust. But do not see much difference, maybe .5 MPG improvement at most. This truck does not do as well as the other one. But as stated before it is heavier and has the extra wheels. But she sure do run good!!

This is a great forum!!!! Keep up the good work guys.
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  #30  
Old 08-10-2006, 06:51 AM
Kennedy Kennedy is offline
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Wow 22+ on a dually! I never figured we'd see a dually cross 20mpg. I've been right around 20 with my single wheel, and recently hit 22mpg. Just need to "back it up" a few times...
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Kennedy Diesel-owner
More than just a salesman-I use and test the products that I sell on a daily basis!
Superflow Lie Detector in house
2002 Chev K2500HD D/A CC Long LT 11.77@ 124mph at 7700# fuel only-e.t. needs help
2005 Chev K3500SRW D/A CC Long LT(SOLD)
2007 Chev K2500 Classic EC Short LT (Sold)
2012 GMC K3500SRW D/A CC Long LTZ Happy Birthday to me! Built 1 working day after my birthday and delivered 7 days later.
2016 GMC K3500SRW D/A CC short LTZ

Custom tuning in house using EFI Live tuning software!
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