Is D13 455hp enough for mountain？

That depwnds on how fast you want to get to the top of the mountain. A 400 hp engine will get you to the top same as a 750 hp engine... Just takes a little longer to get there.

 

Dd15 has max tq of 1700 d13 is 1850 i outpull freightshakers all day long

 

The d13 has an option for more torque over the dd15 the ishift is also a much better trans

 

It all depends on set up of truck, HP not really relative also there is other tricks to volvo like Performance mode and downshifting before the trans does on auto and you will be able to fly up the hill, depends what speed you want to cruise at, usually all mine are set up with 455hp and eco torque 3:08 rears and od trans cruise efficiently at about 68 to 70 but with a couple of tricks will fly up hills, top speed for fuel is about 72 once you pass that fuel economy goes out the window.

 

British Columbia only requires 425 hp to pull 140,000 lbs super b trains through the mountains. I did it with 450 hp.
You’ll be fine at 80,000 lbs