Farmer Duke

I also have a 06 3500 GC dually w/a g56 with 48k miles. I see 13-13.5 mpg . That is hand calculated and 70% highway driving. I always shift around 1800-2000 rpm. I have asked the same question and everybody seems to say the same thing, something is wrong with the truck. I had a Edge EZ on for couple years only got 1 mpg gain no matter what level I ran it on. I like driving the truck just want the "20-25 mpg" everybody else seems to get.

Don M

What size tires?

turbosmoker

i average around 15.5 empty hand calculated and the display claims 17-18. even after smarty jr. i didnt notice any differance. running JR. on sw1.

Farmer Duke

The tires are 235/80/17 stock size have cat and mufler delete, AEM Brute Force intake, Air Dog II, and just went 250 miles about 230 miles were highway driving cruise set at 65 and only 13.44 hand calc. 250 miles put in 18.6 gal dsl filled up same pump before and after, placed nozzle in all the way and when it clicked off I turned the pump off, filled up last night bout 6:30 and this evening same time.

rjmelehan

Farmer,
I have found that diesel foams differently at different times.
So one day I'll get 2-3 gallons more in the tank when filling up than another day.
I think if your going to try to be precise in calculating mileage you need to take the extra 5 minutes or so to completely fill the tank until it does not settle any more.
I have an 06, stock tires, k&n air filter, cat deleted 4 X 4, 4.10 gears. Was getting about 16-17 highway @64mph.

Just installed a Bully Triple Dog. Will report mileage in a week.

Bob in Flat Florida.

simoniz

Another 06 5.9 3.73 owner here with poor MPG's. Smarty box level 3, Straight pipe no convertor. 285 tires and a leveling kit.

Truck has 89K on it now. Hand calculated not pulling 15.9 to 16.3 at best. Overhead says 20 to 21.

Towing my small 6 x 10 utility trailer with a Polaris RZRS in it from Greensboro NC to Princeton WV once or twice a month. 12.5 to 13.1. TERRIBLE!!!! RPMS at 1800 to 2000.

Towing my 24' enclosed on the same trip. 9 to 11.1 MPG's at best! Loaded with 2 RZR's maybe 8000 lbs.max. SUCKS!!!!!

20' bass boat to whatever lake. 13.5 at best.

Bottomline, I'm disappointed, but I gave up on getting any better back in 08. I have recently been pondering on buying something else or keeping this thing and making a few upgrades. Tranny and Turbo...

Rednax

Truck spec
climate
terrain
truck use

are what differentiate one trucks numbers from another. Everything about mine -- spec, climate, terrain and use -- make the numbers no surprise. But I improved them beyond where I started. So can anyone.

The best and worst pro drivers have a 30% difference between them on otherwise exact comparisons.

Records of every mile and every gallon to quit all the boo hoo stuff is how to start making improvements.

Around here (and other truck boards) feelings are substitutes for thinking. Start from scratch and take it seriously. There are guys who do and their mpg is much better as a result of the desire to make changes. Learn. Pays cash money weekly.

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Shorts

Rednax, have you figured at what point the weight of the truck impacts mpg in any way? For example 500lbs over empty? 1k lbs over empty? 2k?

Surely weight plays a role at some point.

Rednax

Hey, Shorts. I'm not missing Dallas this morning any more than I usually do. Traffic here is non-existent. Which would make me think your question has legs.

I don't much notice up to 1k in the back when on the road. I do notice it around town. Less than 500-lbs, no.

But I live on the flat Gulf Coast in a hot climate. Put me in January West Virginia and I'd probably notice it more.

I used to notice even 150-lbs in the gasser V8's I used to own (going back almost 40 years), so I'm happy to say that a CTD is fairly weight insensitive. The "rules" about adding/subtracting weight for mpg starts at north of 350-lbs in my mind.

But I've not driven in the hills or mountains on a regular basis to test that out. A few hundred pounds I've not yet seen even the more "sensitive" worry over (the guys serious about mpg).

10% of 7000 is 700-lbs. That would be noticeable just as 300-lbs in a 3200-lb car would be. I'd think of it as a percentage question on top of the type driving I'll be doing (town or country, solo or towing, business or personal).

With all the above understand that I take great pains on tire pressure against load (weight scale values) as being something to never compromise (tire life and truck handling). So long as I know the points where a tire pressure adjustment is needed (and that ranges from 50 to 70 psi) according to load & duty, I "believe" I have covered the load question adequately.

That's the best I can do with that until my truck use changes from the way I have -- until now -- used it.

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