Help with dd13 fuel economy

Well,i was thinking you could swap jobs between a daycab and the sleeper but if the sleeper does not have wet kit.......All you can do is have a daycab do the flatbed run for a few days.
That can give you the info you need.
If the daycab gets the same mpg as the sleeper.......you know the gearing is wrong.
Alternative is to have the sleeper keep doing the flatbed work but have the driver dropp his speed to where he is doing no more then 1300rpm.

 

For some comparison... Detroit 12.7L Series 60 pre-egr in Columbia. Average load in a van trailer, about 35K lb. Lots of rural two lane hilly stuff along with rolling hill interstate stuff. Northern tier of country all year round. 7.93 lifetime MPG in 476,000 miles on factory remanned motor. I would expect, and demand, that a DD13 get the same or better. Sure, when bucking high winds and heavy, I see some low 6 mpg stuff. But I also see high 8's frequently at other times and even a few low 9's. For something like Texas, I cannot see why similar mpg's would not be reasonable to expect with a DD13.

 

I think you have your truck restricted too much, and like Road Gator said. I would take the speed limiter off, and reprogram the ECU for max hp.. Most people think you will lose mpg with more hp, but I call BS on that. Anyone that I have spoke to said the Detroit's get their max mileage at 1200 rpm. 1400 is more for a N14. I rin all N14's and they get there best mileage at 1450 or so. Same for C12 which is set at 440 HP.

I installed a power harness on my C12 just because he does a nice job, and didn't feel like making one. Increased my HP about 50 hp, and pulls much better. I also gained 1 MPG
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That is on my dump truck and trailer at 84k. average 7 mpg, but i am empty one way, most of the driving is in the city. I bought 2002 Freightliner Century with a N14. Thing pulled OK, but mileage wasn't great. Pulling B-trains at 105,500. Finally decided to see what was up with the truck as I knew it had different flashes for power settings. It was set up at 370 with a fuel economy tune. Surprised the driver didn't kill me. Gave Cummins the engine serial number and what I wanted. They flashed it to 460, performance mode. The driver said it was another truck. He could pull hills one gear higher, and not have to have his foot in it on the flats. The truck gained 1 to 1.5 mpg. My point of this long post is if you restrict the engine settings too much, your drivers will just bury the pedal more, which loses MPG, just human nature.

I would talk to your Detroit dealer about what the best settings for your area is, flash it for max HP, and shoot for 70 at about 1100 to 1200 rpm. My speed limiters on my trucks are set at 83 mph. I GPS track all of my trucks, and they never get near 83.

 

Cory, My flatbed only gets about 5.3 average with the N14. I don't really think your mileage is that bad. Flatbeds are not very aerodynamic empty or loaded. I am running Idaho, Utah, Oregon and Washington, so we have to pull some serious hills.

 

It could be the DPF filter needs to be shaked and baked. Should be done by 240k on normal hi-way useage. Pulling heavy you would want it sooner check the exhaust resistances. Should be below 3.0. Clogging DPF filter will kill your fuel milage.

 

My dd13 is only getting 5.5, 5.3 against the wind. And I run containers here in Texas. Do you think any fuel additives will help?