dd16

Ill bet good money he has a higher gear ratio then you. Maybe diffrent tires but mostly gear ratio. A 3.72 ratio for example will pull away from a truck with a higher horse motor at a say...3.08 ratio on any hill taller then a politicians pecker is long. Throw on diffrent tires and you can get some pretty agressive pulling.

Keep in mind horsepower is great and all but aint a be all end all either. For example a truck with a 600 horse motor but only rocking a say 3.08 is going to have issues in the hills. Meanwhile a dude with a 485 horse motor but rocking 3.72s or 4.10s is going to blow the 600 horse motors doors off going up that same hill.

The really really really basic version is because iirc (and someone correct me if i am wrong) gearing multiplies engine torque by that number. For example im the above equation the 485 horse engine with low gearing (4.10 as higher numbers = lower gearing) is going to have more effective power at the wheels then the truck with a 600 horse engine and a higher gear ratio.

On flat ground however the 600 horse engine is going to be much faster then the 485 engine. Or TLDR low gears = more power to wheels. High gear = better economy and speed. Thats why huge horse motors never really caught on in general application. In most cases slapping some low gears on a truck is going to outperform a big number engine for less fuel in most applications. Also likely last longer too as them high horse motors tend to wear out much faster.

 

It could be the tune your deleted engine has. I’d leave it alone if it is running well.
I knew a guy that had the same experience as you, but he took it to a second tuner that cranked up the power. The engine cracked the liners within four months.
The piezoelectric injectors have to be carefully controlled to avoid over fuelling the cylinders, most places just crank up the injection pulse widths to increase the amount of fuel. But this can cause too much fuel washing out the liners, creating hot and cold spots resulting in cracked liners.

 

Same transmissions and rear axles on both trucks? That’s what makes the difference.

 

A former brother in law had a 600 plus hp isx and his buddy with a 510 hp paccar almost kept up on hills . Both driving w900 pulling 138,000 lbs ..the paccar truck did a full mpg better on fuel.. he turned his down to 565 or something like that . He picked up 3/4 mpg and ran away from the paccar . When it was set at 600ish hp it required higher rpm to keep egt in check so engine cut the hp to be in safe zone is what a knowledgeable mechanic told him that’s why he turned it down. Maybe your 600 hp DD16 is a higher rpm engine as well compared to the 560 version.

 

2014 I think weren’t as good