2001-early 2004 LB7 Duramax Fuel Economy Poll

Fuel economy is one of the top 2-3 reasons why most people buy a diesel pickup.

What we want to do here is help determine what people are seeing for non-towing fuel economy in actual on-road use.

Let us know what your truck delivers.... This poll is for owners of the LB7 (2001-early 2004 model Duramax 6600 engines). We are assuming summer blend fuel.

You will need to vote before viewing the poll data. If you don't own an LB7, but would like to see the poll data, you'll need to first vote in the poll using the "Don't Own an LB7" selection for both the local driving and highway driving sections.

Round your fuel economy averages to the nearest whole number. For example a 16.4-mpg would be 16, a 16.8-mpg would be 17.

MP

[ 01-03-2005, 02:32 PM: Message edited by: More Power ]

I placed my numbers in the 15-16 off hwy, and 17-18 on hwy, but in reality, I run near 17 off hwy, and near 19 on hwy pretty consistently. I'm seldom down to 16 off hwy, and seldom in the low 18's hwy. Just did not feel that I quite made the next brackets...

More Power,
How about a second poll on mileage while towing. Might break it up into weight ranges.

Weight, wind drag and speed introduce a lot of variables when towing.... It'd be tough asking the right poll questions that would include all of the possibilities.

Open to suggestions.... :D

MP

MP, it might be good to run a 3 different polls for trailering, one for pulling gooseneck and tag open trailers (utility trailers, machinery trailers, and open car haulers), enclosed tag trailers (car haulers and rv trailers), and gooseneck/fifthweel enclosed trailers (Car haulers and rv trailers)... and then in each class break down into weight ranges ie.

gooseneck and tag open trailers
3K and under
3-6K
6-10K
10-14K
14K and up

Enclosed tag trailers
3K and under
3-6K
6-10K
10-14K
14K and up

Enclosed gooseneck/fifthweel trailers
7-10K
10-14K
14K and up

additionally, give the respondents an opt out for each weight category as you have done on this poll so that people may just view the post. This will allow people to respond to the weights which they most pull

just my 2 cents

What towing speeds?

MP

45-55 mph
55-65 mph
65-75 mph

I hope I see 19-20 MPG some day out of my truck. Be curious to know how many of the 19-20 range are stock and how many of those are 6 speeds.

I just did an extended highway trip and purposely drove between 55-60mph the whole distance to check my mileage. Ended up getting 23 mpg (Imperial gallons), so this 19 mpg US (assuming my math is right).

2003 LB7 D/A with Magnaflow 4" exhaust and K&N air filter.

I just did an extended highway trip and purposely drove between 55-60mph the whole distance to check my mileage. Ended up getting 23 mpg (Imperial gallons), so this 19 mpg US (assuming my math is right).

2003 LB7 D/A with Magnaflow 4" exhaust and K&N air filter.

Over the first 10,000 miles I could only get around 14-16. At about 10,000, everything seemed to run "free'er"....most recently a interstate trip back from Kansas in August running at 75+ returned 20-21 MPG !!! [img]smile.gif[/img]

Quote:

---

gooseneck and tag open trailers
3K and under
3-6K
6-10K
10-14K
14K and up

Enclosed tag trailers
3K and under
3-6K
6-10K
10-14K
14K and up

Enclosed gooseneck/fifthweel trailers
7-10K
10-14K
14K and up

45-55 mph
55-65 mph
65-75 mph

---

That's 39 polling questions, not counting the fuel economy range and "does not apply" selections for each weight/speed category. :(

MP

Total miles driven in 2004- 17,811
Total fuel used- 825.408 gallons
21.58 mpg average for the year. No complaints.
2002 GMC reg cab,4X4, ZF, stock. Very light towing and some snow plowing.

I have noticed one thing not mentioned in the poll. In the summer months I typically get an average MPG (60% highway) of 17-18. However wintertime sees this drop considerably to the 14-15 MPG range. I assume this is due to the greater amount of "cold weather additive" used to keep diesel moving in the cold weather. Unfortunately for diesel owners here, Diesel is also at its highest price during the winter (competing with the fuel oil market). No big deal but my old 6.5L chevy never saw this big a drop summer to winter.

It's a combination of winter fuel and cold temps. The engine doesn't run a top efficiency until it gets up to opperating temp.
Cold weather slows this process down a lot. Sometimes if it is really cold, my truck never even gets over 180 degrees unless I'm on the highway for awhile. Don't forget about having to turn gears and driveline components in cold lube fluids.

Worst mileage recorded, 11.73mpg, gooseneck loaded GCVW=24,500.Best recorded 20.73.Running empty@ 68 mph.

Overall Average-49,005 miles, 2,736.93 Gallons=17.9 MPG. in 1101.1 hours=44.505 MPH lifetime average so far. I'm surprised it's that high. I did 453 offroad miles Hunting in Colorado, some it crawling through the canyons in 4 low. It ain't my old K3500 dully, but I sure like the fuel mileage better.

I would like to know how you can get over 17 mpg? I have never got more than 16.5 weather I baby it or not.

17 to 20 most common

Check out results on this link below question (12), results of 61 people from 2001 to 2003 Chev/GMC owners

http://hobbycanada.qazam.com/Surv/Ch...to%202003.html

I can't believe the excellent milage you guys are getting. I got 37k on my truck and have NEVER been able to go 400 miles on a tank. Therefore, I have never seen even 13mpg.

Dealer tells me that is perfectly normaly for a big truck like mine (see sig). Are there any other 3500 4x4 guys out there that have been able to break 400 miles on a tank full?

I have a little over 17K on the clock now and solo average about 14.5 to 15. Never have seen much better than that on the average. I do have J/A installed so that may be skewing the numbers. Towing my heavy rig the milage will be between 9.5 and 11.5. I never drive over 70 with the fiver.
Denny

I have and 02 with "Edge" and never see more than 17.5 solo and 10-12 pulling my 5th wheel. I did go as low as 7.5 in North Dakota, but that was with a 40MPH head wind and 50 MPH. While I would like to get better mileage, I'm a little to heavy footed to really realize any better.

At 75 on hwy, I am disapponted to see less than 22mpg at 60 I get 24mpg my city average is 17 with 28000 on the clock the only mod is a ventalated air box and a soft toneu cover

I filled up late yesterday. Fuel economy for this tank was 17.8 mpg - winter fuel in January. Pretty typical.....

MP

Good Day!

birddriver: Are you calculating your mpg from your odometer & the gallons you pump, or from an electronic readout in your cab? If you

Good Day!

birddriver: Please don't take this truck to your dealer, then get it back & tell us you now get 18 mpg - get it to someone who knows about these things & find out why you're doing so well, if that's possible. :D Then for those few of us where mpg is more important than snort, we can duplicate whatever you're doing or what's different about your truck. ;)

Blessings!

Brian Johnson, # 5044

Last year (winter) I went on a 6000 mile trip towing my 28.5ft tag loaded at around 9000lb. I drove the northern route to Phoenix, flagstaff and down,then the southern route back to IL
Going out I averaged 70mph coming back was 60mph. This was hand figured at every stop as well as at the end.
Without towing and traveling I run 72 and will get 17.5-18 around town and normal driving I get 18-18.5

03 d/a, cc, 41K miles. Consistently average 18mpg. Haven't seen anything over 20+. I filler up to the top of the cap everytime and calculate the mileage manually. Daily driver, 38 miles one-way to work, 97% freeway, doing 70mph. No performance mods. Have had 1 injector replaced and 1 allison tranny replaced.

22mpg Highway @ 80mph.
17.5mpg mixed driving.

14-16mpg towing 6,000lbs @ 75mph.

I tow with Attitude set at level 1. Stock exhaust, stock air box....

Hey all,
I've never gotten better than 14.5 mpg D/A and I'd like to know what I have to do to improve. I've got about 35,000 miles now..
Thanks for any input... :rolleyes:

SORRY for the long delay in a reply.
A few times I have checked the mileage by hand.
mostly it is of the DIC. Fuel used is always within a 1/10th or so from what I refill to.
I always fill it to the brim so there is no guessing in that.
When I modified the air box I Removed three sides leaving the engine side,bottom and the four corners, also removed the foil patch from the inner finder. Then I smoothed the top and heavly blended the air tube transition and blocked off the little bulb "do-hicky" at the other end.
I use No additives or synthetic oil.
The best I can say is that the LORD has blessed me with a good truck!
Please note: My truck is TWO wheel drive.

Birddriver, can you provide a little more info/detail regarding what you have done to your airbox. i.e., (I smoothed the top and heavly blended the air tube transition and blocked off the little bulb "do-hicky" at the other end)

Thanks, John

HEY DA_MAXX, WHAY DID YOU HAVE TO HAVE THAT ALLISON REPLACED? [NOISE]?

Good Day!

Thanks, birddriver. Guessing your airbox work & 2WD are helping lots. Sure wish I had some time to play with my junk

Using a Dremal tool I removed all the cross hatch support from the top lid and smoothed it. The air tube transition needs to be rounded as much as posible if you cut to much You can use some of the now scrap and a good soldering iron to weld up holes.
((((( Take the MAF sensor out of the air tube BEFORE you begin )))))

I regularly get 18.6 driving back and forth to work (100 mi per day 60 Hwy/40 City). On the open hwy, the mileage is directly related to speed.
Spd/Mpg
60/24
65/22.6
70/21
75/20.2
80/18

The truck is 100% stock 2002 DA 2500HD CC LB. I run AmsOil 15w-40 synthetic oil and a OEM style K&N air filter.

Mike .T.

2 years ago I drove from Reno, NV to Anchorage, AK on $232.00 worth of fuel, mainly due to the fact that I only had $240.00 left on me and I was forced to drive this thing like grandma to church. At an average price of I am guessing around $1.50/gal back then divided by 3200 miles or so it comes out to about 20.5 mpg. This is seriously babying it, never acelerating hard from a stop at all and driving at a max of 70mph with the cruise control.

I think that some of you never see over 16-17 mpg because you are as addicted to the right pedal as much as I normally am and enjoy the power and fun that these trucks offer. Those experiencing the high mileage are babying it, never accelerating hard and never drive very fast.

I have also driven about half way thru Canada coming down from Alaska never going under 90 mph and let me tell you I only got about 350 miles per tank. Once I realized how much my speed and acceleration affected mileage I was forced to backoff because at the rate I was going I could not afford the fuel. Then I got up to 600 miles per tank.

So speed and acceleration makes a huge difference. For those of you never getting great mileage, don't feel bad, you are just driving the truck the way it is meant to be driven. There always is a trade-off between mileage bragging rights and having fun, and I suspect that it is way more fun to get worse mileage than it is to drive this truck like a model T just to say how good of mileage you get.

One thing to remember also is sometimes the electronically controlled torque converter slips more than it should, and the truck can feel sluggish and mileage can drop down to the 10-12 mpg range. When this happens, and it happened to me once, if you do the tranny reset sequence, which is going 50+ and shifting to first and bringing it down to a stop 3X in a row it will reset the computer and Voila, the mileage and power is back.

Thought I would add to the mileage info,just bought used 2002 Silverado C/C D/A.Am getting 18mpg empty hiway,17 around town short trips,Towing 28' Jayco probably around 14-15 thousand gross 11 mpg through Texas and I-40 into NM turned north into 30-40 mph headwind to Alamosa Co. 9mpg. Came across mountains into Grand Junction 12 mpg I would like to do better but am satisfied so far. The D/A will certainly pull,Let the Allison do it's thing,dropped out of overdrive occasionally in the mountains and strong headwinds.Running 60-65 mph Shorty

I didn't see anyone mention this so I will. Its not only your rate of acceleration that counts for fuel mileage, its also your rate of deceleration. I suspect that is where a lot of you are loosing out. With these high compression engines if you just jump off the accelerator you are wasting a lot of energy stored in the velocity of the vehicle. You've spent the $$$ to get it up to speed which is where most of the fuel energy is used. It doesn't take much to hold a steady speed. To keep from loosing more fuel mileage decelerating try just backing off a little until you see the speedometer just start to decend. Try to keep the rate of decent in the area of coasting, where you are not using the engine to drag down the vehicle speed quickly but a just supplying enough fuel to keep it at a rate of slow decent. Your best mileage will be when you accelerate and decelerate at a slow rate and cruse at a steady speed for hours at a time, like out in the middle of nowhere. Remember its the rate of change that makes the difference. Food for thought.

For all of you using chips/programers, remember your truck DIC MPG reads too high when using chips/programers. You have to calculate the MPG the old fashoned way. By the way, the DIC Gallons used display also reads inaccurate, too low, you have to use the pump reading when doing you MPG.

I purchased two 05 trucks in nov & dec 04. both are 2500hd 4x4 d/a's one cc & one ext c. I drove each of them kenosha, wi. to florida. they both got 22-23 mpg for the whole trip. now one has 13k miles and one 6k mi. one is avg 16 mpg and the other 17 mpg local driving. when we drive out of town & run steady we see much better mpg, as expected. the secret,i think,is keeping your foot from showing you how much power is under the hood! i carry a lance 915 truck camper sometimes. with that,i get only i5mpg on the highway - but i keep the speed down to 60 to 65.