Can someone explain displacement vs HP to me?

I know most manufacturers say there is no "break-in" period for a modern engine, but they always seem to start to pull better once they get some mileage.

 

Also, is rest of power train speced the same?

 

As a "general" rule a larger displacement engine will last longer than a smaller displacement engine doing the same work at the same power level.

Think about it, a smaller engine needs more fuel and air per L of displacement to make the same power as a larger displacement engine. Its working harder to achieve the same amount of work. On new trucks with aftertreatment systems it can be considered an advantage. The engines need to be worked to run efficiently. No sense putting a 500 hp 16L in a truck hauling legal or lighter when a 12L - 13L can do the same job more efficiently.

 

I've always wondered why the 13 you can get 1850 but only 1750 with dd15. Seems like they're pushing the 13. If i had to go with a new EPA engine for 80k and under I'd get 12-13L