Ford vs Ram vs Chevy diesels

06Fargo wrote:
Proper scientific test :)

I heard this at the Flying J:

Rotating engines can only produce torque, which does the work.

Which is why the nearly 400hp RAM Cummings cannot do the work in 12 hours at the speed limit that a 400hp ISX Cummings can do in a heavy duty truck hauling 80,000lbs, expressed in tons moved x distance in 12 hrs., at the speed limit.

Did I remember that right?

You more than likely remembered it correctly and it sounds exactly what a trucker would say, but it is completely inaccurate.

A 400HP engine is a 400HP engine. It does not matter if it's 1 cylinder or a 16 cylinder. It does not matter what the fuel source is. They will do exactly the same amount of work.

With those two engines what matters is duty cycle. The semi will have 90% duty cycle and the pickup more like 20% duty cycle. The Semi will be happy at WOT all day long where the pickup will either derate or be dead in less than an hour. That's why the pickup engine is considered light or medium duty and the semi engine is considered a heavy duty engine.


Here is 4 HP pulling a semi truck out of a snow bank.

Here is 2 HP pulling 18,000 lbs!!

In the second video those horses are putting out WAY more than 2 HP but they can only do it for a few seconds. Much like the pickup, they have a very low duty cycle when pushed to make a lot of HP. Much like the semi, they can make 2 HP all day long. At least that's what Mr. Watt tells me. :)