When I pull heavy loads out of soft fields or down soft roads, its hard to beat the off-idle torque of the big inch Cats. The engines may all have the same horsepower rating at 2100, but thats not where I let the clutch out.
Here in manitoba a trucking company called Gee Tee transport has 5 volvos with the d16 @ around 600 hp. pulling super b. he said the isx cummins outpulls it, with less horsepower and uses a lot less fuel. he didnt mention cummins but he said his d16 (he showed me too) averaged 4.1 mpg. the worst i have ever done with my isx and super b is 4.5 last spring on soft gravel roads all the way. no pave at all. so....... cummins all the way for me.
I would have to say cummins for the most part Best detroits i have been around were the 12vs and the 8vs. Also ran a older IH 817 inline wished they would have brought that back also that big 800 v8 ran well in trucks. And for cat lots of high mile 3406s around never cared for them my self only cat i ever ran was a 3408 loads of power
A testemoney from one of our drivers (the one who drives the purple truck lmao) says that the Cummins 400's have absoloutly no guts, he has to go into 3rd or 4th gear in bottom box to get up some of the hills around here with only a single trailer on.
But...he also says that while it is a bucket of crud in the hills it will outrun and leave the Western Stars that the company has. those trucks are a year old and they run Series 60 Detroits. they have stacks of torque but dont hook in as fast as the Frieghtshaker.
But then again...I believe this may be due to the fact that the Western stars have Speed limiters...and the Purple People Eater doesnt..