Fuel Mileage-what's yours?

I've noticed that a lot of new trucks with Cat ACERT engines have really high rear ratios, like 3.36 and 3.25. I read some where that these new engines could lug down lower than the older ones and that's why they spec'd trucks with higher gears, and also to help get better fuel economy. Does the high ratio have much impact on the power of the truck as far as getting up to speed and into top gears? My dad and brother both have F-150 pickups with the 4.6L V8. Dad's has a 3.55 gear and my brother's has a 3.31, which should get better mileage, but it has a harder time getting into overdrive. Does this same problem exist in high-geared tractors?

 

Yikes!!!! What the heck is going on up there?

I'm sorry....I thought you made a boo boo....I guess I did.

 

2000 Mack 400, 10 speed Easton Fuller autoshift, usually running about 1450 rpm at about 62-63 mph and I get about 5.5-5.75 in mileage. And that sounds horrible, but the trailers I pull are real fuel hogs. Lots of plumbing, hatches, valves catwalks, and other stuff hanging out in the airstream. Ribbing vertical and horizontal on the sides, and the ends have ladders and plumbing at that end of the airflow. I have found when I pull a van, I get 6.75-7.00 mpg, so this is all the result of the trailers I pull. My trucks specs and my driving technique are much better than you would ever guess from seeing the fuel mileage numbers.

 

But what kind of trailers are you dragging behind you. I guarantee I can pick up at least a mile, and probably more by hauling a van. But the pneumatics are what we haul. I've had a van hooked to me only one time in three years. I have a buddy of mine that had a F/L Classic, got 4.5 with us, and is now getting close to the 6 mark once he switched to another company and is pulling a van. His setup is a former US Express truck. Fuel mileage isn't just the truck, the trailer has a big impact on it.

 

The last time I pulled a van was back in the 80s unless you count storage trailers. It seemed to me that I got worse mileage pulling the van. But then again mt truck wasn't very areodynamic (R Model no fairings) and I am compairing it to hauling crane boom and counterweights on a flatbed.

I was also just thinking about my old Mack wrecker. It was an LJ single axle with an EN707 gas motor in it. If I kept it in a good state of tune, it got a wopping 3 MPG

 

Has anyone ever checked what kind of mileage you get bobtailing? Any guesses? I'm going to be running 1500 miles bobtail soon.

 

Hold the speed down, and resist the temptation to accelerate hard and you do pretty well bobtail. At the very least you have shed the rolling resistance of the trailer and cargo weight, and lost at least 8 tires in the process. I don't bobtail enough to have a firm answer about what it does to mileage (and I hope not to since trailers mean money!) but just the weight difference alone is going to allow the truck to do almost as well as it possibly can.