Fuel economy with a diesel truck ?

[MrJimi]

What kind of MPG are you getting empty/loaded and what (if you know rear axle ratio) do you have and what mods/chip/tuner are you using if any.
I saw two threads posted by another member that was truly impressive with all the info. Thanks
Jim

 

[radman1]

You may want to be more specific. Are you considering new vs a few years old? Newer trucks with DPF and more hp are taking a hit on mpg. Most trucks sold in the past year with DPF are getting 11-15 mpg. Less when pulling very heavy loads and rear end ratios such as 4.88. Ford has just started putting 3.55 rear ends as standard on job 3 250/350 diesel trucks instead of the 3.73. 3.73 is now an option.

 

[MrJimi]

Good point, I can not afford a new truck, I have a 02 F-550 with a 7.3 and a 4 speed auto with OD and a 4.88 rear axle. I've been told that I can pull anything but not to look for great MPG. Anything over 10 will make my day empty
Jim

 

[john_bud]

MrJ,

I'd flip out those gears in a half a heart beat! You can probably get 3.73 with limited slip from a salvage yard for a couple hundred bucks. That's probably worth 2 maybe even up to 4 mpg. Don't know how much you run each year - is it worth it or not?

 

[MrJimi]

JB, my rear axle is not like the everyday rear, It is crazy huge. If I put 2,000 miles per year that would be a high number, I only bought this to pull my trailer a few times per year and I have the 4.88 limited slip now. I know it's gonna be a fuel hog
Jim

 

[Nat]

Jim, I doubt it will be a "fuel hog". I have a 2001 dodge with the 5.9 cummins and 4.10 rear and get 19+ around home. I get 13 pulling my 14,000 lbs 5 th wheel. I try to stay under the speed limit on interstates, around 65/68. If I had the 550 with the 7.3 I wouldn't consider trading cause it ain't available anymore, and the alternitive isn't so great. how do you like it with the pickup bed now? later, Nat

 

[john_bud]

MrJ,

No big deal. It's not like your a door to door sales man. Getting 10 vs getting 13 isn't that big of a deal when you only go 2k a year.

I did the math quick. At $3.50 a gal and 10 vs 13 mpg for 2000 miles a year the dollar savings are about $160 a year. Just so you know. It seems that 160 bucks a year is a small price to pay for the ability to yank houses off thier foundations.

A cheap exhaust trick is to get a larger muffler. Donaldson makes some that are large, free flowing, quiet and about $100. With them, longer and larger diameter are better. Might get a touch more.

Post back with your first couple tanks fulls. Hey, it's for TBN - go for a cruise! Git'er done!
jb

 

[ttstraw]

Here are my real numbers.
Truck is a 05 Dodge, Cummins, 6-speed, all stock, quad cab, 4X4, short box, axle ratio is 3.73

2006 I did 16,910.4 miles at an average MPG of 16.7
2007 I did 14,660.5 miles at an average MPG of 16.4

Now, empty at 65MPH on the freeway I have seen 22MPG but mostly it sits right at 21 for an average.

Empty back and forth to work, if I behave, I average 17+, this is anywhere from 25 to 45 MPH rolling country roads with a few stops.

Pulling my trailer, 30' bumper pull camper that loaded runs ~8500lbs, it will vary from 12 to 14 MPG depending on speed, terrain, wind.

The above yearly #'s include all of this lumped in together. Overall not to bad for a 3/4 truck that is a heck of a lot of fun to drive.

Tom

 

[MrJimi]

Nat, LOL It's still in my garage getting the little things worked out. I still have to make a couple of bed mounts and after that I am going to attempt to mount dually fenders that the dealer says wont fit a single wheel bed? I really hope I can do it and If I have to mold the fenders to the bed, I will like it even more, the one time I tried the fit I was alone and just 2 tie-down straps and it did not look too good at all but I have done P&B most of my life and It should work. And after all that I have to remove the bed again to paint it and the frame .
And your F-550 should have the same rear as mine, really huge.
Jim

 

[cschlaps]

I have an 03 Dodge Cummins 5 speed short box quad cab on 35" tires. Not exactly sure on the rear axle, but it's in high 3's. No chip or any other mods. 135k miles.

All highway at 55-60mph (below 2000 rpm) and I can squeeze 20+mpg out of it. My calculations factor in the tire size difference.

If I'm doing a mix of street and highway driving, 17-18mpg is typical.

It's a great truck! Now I just need to find myself a diesel tractor...

Chris