Can a 400HP truck carry 35K 53ft van load on steep grade easily?

It isn't that simple, and your definition of horsepower is lacking.

On level ground you need horsepower to gain the highest speed.
But for acceleration and holding speeds on a hill you need torque.

 

The first big power engine, as much as I hate them, was the 237 Mack, they made enough torque where you could put a 6 speed behind it and still get them to pull, without having your arms stuck through the steering wheel all day, when the late 70s/early 80s rolled around you could not swing a dead cat without hitting a truck with a 350 Cummins in it, they were quite a step up from the 290/335s, of course you had the ktas, 12v etc floating around as well but the 350 then 400 owned the market for quite a while until the b model 425 cat started coming around. A high 4.xx or low 5.xx would get you to 55 mph a ~2100 with most of the rto 13s of the day, maybe touch 60 on the down hill


A 400 hp engine using 400 hp to move a load is going to be harder on fuel then a 550 hp engine that is only using 400 hp, with the right driver

we just sold our last 400 BC earlier this year, it was a day cab Pete with 3.70s and an RTO 13 on 11/24.5s, while my truck was getting inframed I averaged 5.8 mpg with it running my reefer at 80kish, which I thought was pretty good for a 32 year old truck, we still have a 290, and a 237 in the yard, although I’m hoping my uncle will finally let us give that old bull dog the ole yeller treatment


Drivers today have no clue how good they have it

 

Torque is the low range of the motor.

Power is the higher range of the motor.

Who runs around at 1200 rpms.

My current motor torque is 1100 - 1400. Power 1400 - 1700.

My last otr job.
Phx to flagstaff. 30 minutes faster at 1600 rpm over 1200.

In the summer time when you're running hot. You increase the fan speed by increasing engine speed. Power range rather then torque range.

 

Targeted audience. My apologies.

 

Spot On...

 

With the right driver a higher horsepower truck with the same specs as the lower horsepower truck will get better mpg's. You just can't have your foot in it ALL the time

 

Yup
My first rig was a cabover with leaf springs , no power steering and a 350 BC Cummins 9 speed .
It did have cold AC though .

hauled the exact same loads as todays rigs do . Took a extra 40 seconds to go up a hill verses todays rigs .

 

Spent a lot of years in the Northwest at 105k gross with a 475hp engine so I’m sure 400 or 455 will do fine at 70k gross. Although my current engine is 510hp and I’m also rarely above 70k gross and I just sit and cruise at 1100rpm all day.

 

More HP, less foot.

 

510 is just about perfect for all around 48 freight hauling.