NEW TRUCK gear spec help

I don't think you can get good fuel mileage with a long hood truck, pulling a quad and running 70mph

 

That c15 acert can be made to get better mileage but you'd have to slow down too

 

If fuel mileage is the goal, you've picked pretty much everything wrong to do it with. From truck to weight and speed to operating area.

 

Might try a 579, they are still very nice trucks and mine with a 455hp MX 13 and 3.25s pulling a dump gets around 6.5 doing 100% 80k-85.5k and 8-9.3 while empty Not as nice as a long nose but it rides better then my bosses old 389k did and the sleeper is to die for.

the 510 tune supposidly still gets simular MPG, however i dont have the tune yet so i cant confirm first hand. I do plan to up my 455 to 510 and upgrade my clutch to handle it as soon as i recover from the 5th wheel incident.

Gimme a bit to charge my laptop and ill pull up davie4 to show you the actual engine logs for the last 10k miles.

 

I mean your not wrong. How about go for something in the middle and get a 567? 2022 Peterbilt 567 | new Tractor For Sale | 30A763066B You get most of the looks of a square nose but a lot of the aerodynamics of a 579 and weight in between the two. So best of both worlds there.

Im sure the MPG would be simular to a 579 maybe not as good but likely close. I dont like ISX engines. Heard to many horror stories of them going boom due to pumps. MX engines usually have sensor errors but with mine i pulled and cleaned all my sensors and it fixed 99% of the emissions issues it had from the dealer. Just need to have a davie4 analog tool such as my diesel laptops system to keep em happy.

 

Pulling the weight your pulling at 70 your getting good fuel mileage now