Fuel mileage

On the top speed at 59 what's your rpm range 500hp in a 10 speed should be like 75-85 before you run out of rpm but dont know your trans gear or tire size and if that's all its got on the top I would think you would be money ahead going with a 13 speed trans if you go to the dealer they should have spread sheet with trans, rear end and tire size to give you engine rpm and max rpm that dont sound right I have worked on heavy haul trucks with 4.76 gears that will still run over 80

 

Get the progressive shifting off. It doesn't create any fuel mileage in an off-road situation, as well as making things a lot more annoying for the driver.

The trucks aren't doing badly given your weights and the fact that it's local work. However, I'd concur with the other opinions that your rear end ratios are still too tall, and a ten speed frankly is a poor choice for off-road or heavy work.

I've done a whole bunch of off-road work, at similar weights, albeit with a tanker. The best fuel mileage we got was with ISX600's, 18 speeds, and (I think) 4:56 rear ends, in 2012 Peterbilt chassis with a 5000 gallon tank on the back. Mid 6's were the norm, even with extensive PTO time.

 

If running off road and heavy, you may want to even look at an Allison automatic. There is a 6 speed automatic, but with the lock up torque converter you have from what people say, 12 gears. The over drive is really tall. They work well in a dump truck, but not sure how well they would work for your application.

 

Mack CHU-600 is worth a look..... mp8/mdrive auto trans.....

 

An auto shift and automatic are not the same, an Allison is a power shift transmission with a torque converter. An auto shift is a truck with an automated transmission, it has a clutch, not a torque converter.

 

Stop showing off with your good MPG.....



Normally over 100k lbs, and wide and tall.

Martin

 

Now thats the way to burn!