Will adding HP help with MPG's?

What kind of RPMs are the other two trucks turning at highway speeds compared to the one with the N14 525?

 

I can tell you from personal experience that my 05 C13 gets around 1mpg better after a 500 horse tune. However, it's not the horsepower that does it. It's the torque. Mine was set at 435hp/1450ft.lbs. It's now at 500hp/1700ft.lbs (I think those are the numbers anyway). I drive it the same as before the tune (like a little ole lady) and am at 6.7 this winter. Was 7.6 back when it was warm out. Last winter I was at 6.0ish. And early warm weather was only at 6.5mpg. Got my tune at Diesel Doctor in Effingham, IL. It has been said there are others that can tune it better than them for quite a bit more money.

 

With a good driver you could see better mpg with higher hp but most drivers don't care its a race to them smash accelerator to the floor and go. Give your drivers a incentive to get better mpg by either bonuses or something else first and see if it increases. All the hp in the world wont increase mpg with a bad driver.

 

Higher HP doesn't give better fuel mileage, period. If that was the case, my 400HP engine should be doing far worse than your trucks, but I'm getting 7 to 7.5 However, you are also comparing Cats with a N14-Cummins, which is going to vary. How many miles are on these engines? When have they been overhauled? They might need tuning, they might just be tired and in need of major work. There are a lot of dynamics to fuel economy. Heck, a simple crapped up sensor can throw fuel mileage in the toilet. The biggest factor, however, is how those trucks are being driven. Multiple trucks, I'm guessing, means multiple drivers. You can put two different drivers in the same truck and see a huge difference in mileage.
(Looks like shovel98 and I were typing at the same time!)

 

I agree on the torque. I was told of 500hp/1750 torque up from 435hp/??? torque.
My mileage didn't go up that much but still about .2MPG.
Don't get trapped by the higher pitch of the turbos. You don't wanna hear them or you ruin your mileage.

@Rusty Bolt where do you take your numbers from?
Just curious, because the mileage I'm getting on the Qualcomm ist off by about 12% after the tune. Before it was quite accurate with my records from pump to pump. And the Qualcomm takes that info from ECM.