My truck with 4.10s gets better fuel economy than my father in laws with 3.54s. That's loaded or unloaded. Both trucks are 5 speed NV4500s. Last time we both pulled loads together he burned over half a tank more than me. I think the difference in gears has a big effect on the load of the motor. He was down shifting and throttling harder on hills and take offs than I was. The lower gears means the motor doesn't work as hard.

 

I'm getting anywhere from 20-22mpg mixed hwy and local. Straight hwy I can see over 25mpg. On the hwy I run 65 mph, in 5th, and the rpm is right around 1800rpm. I'm running 235/85/16, highway tread, with 3.54's.

BTW the sweet spot on our B-Series cummins is 1750-1900-ish RPM. This is the optimum power/torque zone and therefor the motor is at peak efficiency.

 

Is that US MPG?

 

The Canadian vs US gallon is pretty irrelevant now days....since all fuel in Canada is sold by the liter. So if you are doing the math, then you just use 3.78L for a US gallon...which is how I figure things.

 

Yup, its just the math that many get wrong.

 

Okay so the overall best mileage seems to be with lower gears well then im toast I am downright certain mine has the 3;07s but I could be wrong and wb JQ he says he gets up to 27mpg pushing 430 hp on fuel

 

If you don't have the optimum HP to turn the double OD and high rear end gears of the 3.07s, you will burn more fuel. I would think the friction drag losses on JQs truck is like a 4.10 truck with a loaded bed of weight. 400hp will be needed.

This also brings up another point. 3.07s and 3.54s create more heat due to drag, friction, ring gear contact area than a comparably 4.10 equipped truck.

Posted via Velocity LG ALLY

 

That is very interesting....good to know.

 

Yea its great info thanks again guys but what would your typical W350 get for mileage?

 

My best was 18.8 MPG and I consistently see between 17.5 and 18. That is with 90% of my miles on level freeway going between 60 and 65 mph. All terrain 235/85/16 tires, no lift, DRW, 4.10 gearing, 5 speed. All stock motor with exception of 3200 spring.

 

Well I know the dually I am looking at has the 5 speed buttt I am not sure of the gearing either 4:10s or 3:54s

 

I would think that flat bed truck you are looking at should be lighter than a standard bed truck as well?

 

With POD's and all my other crap, I am averaging between 17 and 18 in the winter.

 

Even if all you got was 17mpg, its a darn sight better than my 6mpg with the 360 gasser! not to mention I can climb hills at twice to three times the speed!
I love my Diesel!

 

I am guessing it depends lol