detroit 14l terrible mpg

If I'm correct, you run 78 up there which does have hills in Alabama but since you're coming back empty you should be averaging about 6 mpg round trip.

You got me on this one. The only other logical explaination would be fuel leaks (but that would be obvious) or unburnt fuel being spit up out the exhaust. That would make sense with the computer and the manual calculations not agreeing....

 

Wow, that is incredibly bad mileage for what you do, even the 5.5 in your other truck. When I pulled a dump wagon out and back, I was getting closer to 6.5, and that was running out loaded from the river in Knoxville into the mountains in western NC and SE VA. I also didn't have a lift axle..Maybe you're just not supposed to pull a dump wagon with a Detroit...

Keep after it, hope you find something soon.

 

93 t600 detroit 11.1l 350hp 13sp .73 od in 13 .80 12th 3.55 rears swapped power divided for lift axle
(thinking of making a 12.7l out of it or swapping it.) Dont know if itll hurt my mpg (any idea?)

88k pounds running back empty for 530 miles 3 daily loads, almost no stop almost no idle or hills im getting 6.8-7.2 mpg at 52-54 1250-1300 rpm in 12th.

Yes takes all day and I burn no more than 78 gals if I go 63 I would be on the deep low 6s to 5s

I calculate this with fillups over time been doing this for 2 years and just got a scangauge d which agrees with my statement.

Maybe buying another truck will be cheaper for u, mechanics will ruin you..