B+O

he's half right.

in essence it's torque that gets you off the line and torque that keeps you going through the end. what HP is, is just a way to tell you how fast you can get the torque applied to the ground in the higher RPM range.

diesels don't play nice with high rpm, so they're torque monsters. Moreover they cant take that torque out to higher rpm-or a longer distance per unit time-as the get inefficient all you really end up with is slabs of torque, and a decent amount of hp (or the ability to use the force or torque it's capable of producing for longer and longer amounts of time.) if you peep a diesel run out, they usually fall off pretty hard after 3000rpm.



EDIT:



just found this. lets examine...

Lightblue=torque, darkblue=hp

oh where they cross is about 4000 rpm just for reference.

See how the light blue is huge on the bottom end? that's the torque. it's extremely stong on diesels. but since they aren't very efficient at keeping that torque as the distance covered per unit itme increases, it falls off...and HOW!

the dark blue is the HP. but if you can see, the light blue is falling off pretty steeply, the dark blue is kinda still going up for a minute but then falls off just as hard as the light blue? that's the torque falling off pretty hard, and since the torque is what you feel and HP is a function of that force over a said amoutn of distance per unit time, if you reduce the force per distance/unit time. you're going to have lower output. and that's what's happening in this dyno sheet. the force is falling off, as distance covered is getting greater, less force for the distance covered is equal to less work done, less work done is less ability to accelerate, and thus "less horsepower"