Will adding HP help with MPG's?

If you turn up an engine and run it the same as before in theory you should see a little mpg gain. Pops had a formula 315 he turned up the fuel and got 1.5mpg better. Avg 6.5 before turning it up and got around 7.5-8.0 after. The right driver will see a mpg increase. Our ford 5.4 triton's we tuned up a bit with intake, full exhaust and a mild ecm tune. We went from 16mpg to just under 18 on the highway. You just have to keep your foot out of it or you won't see any gains at all

 

I run a C15 cat, it does not like pushing high RPM. It pulls from 13 through to 1800. Anything after that I think I am just th roughing fuel away. On the highway I keep it to 1500 RPM
I average 5 miles to the gallon but I am pulling max loads 140,000lbs.

 

$300

 

If you're asking about my MPG numbers, I keep really good fuel records. Which only slightly disagree with my ECM.

 

Peak torque on the C13 is at 1250 rpm. So, it doesn't pay to get much over 1500 rpm. Can't see the C15 being too much different.

 

OP stated he is running 1700-1800 rpm @70 on the highway I was thinking this was killing his mileage. I try to keep mine around 1500 rpm

 

I have an ACERT C15 in mine,. and my biggest MPG improvements came from changing my driving habits and learning to keep the motor in its sweet spot.

I have no experience with the C13. The C15 I have (435/1650 BXS retuned to 500/1850) likes to cruise between 1350 - 1450 RPMs. Thats the sweet zone. Unfortunately with 3.55 gears and 22.5 Lo Pro tires,.. 1450 rpm means no more than 65 mph. 70 mph is 1550 rpms,..and I lose .5 - .75 mpg from doing 70 vs 65 mph (Depending on load and terrain).

When I first got my truck it was a lush,..averaging 4.5 - 5 mpg no matter what. I saw about .5 mpg increase from doing little things. Replaced Davco unit, religiously maintaining air pressure in the tires, retuned to 500hp, cleaned out the CAC and replaced all the boost couplers. Had overhead done and replaced soot choked mufflers.

I added a boost gauge (Columbia has fewer gauges than a Honda) and started to watch. Feathering the pedal to stay out of high boost. Short shifting when ever I can. Changing my driving habits netted me the best results. Averaging 5.5 - 5.8 pushing almost 1.3 million.

I recently had an inframe done with new head. I am now seeing 5.5 - 6 mph with winter blend fuel,.. back in Sept till about Oct,.. I was seeing 6 - 6.5 mpg tanks between refueling.

In my opinion,.. you will see your best results by giving your drivers incentives to get better mileage. I was the same way when I first got my truck. All I wanted to do was deliver the load as fast as I could in order to get the next load and run run run. In my mind thats how I was going to make the most money. I was blowing through well over $3000 in fuel a week back in 2014. Fast forward 2016,.. I'm still doing the same number of loads, a bit less on the rates. But much less in fuel costs as well. Between lower fuel prices and better mpg,.. I'm currently using between $750 - $950 a week in fuel.

Hurst

 

There's alot that goes into this as other's have suggested, but in addition:

-Are the trucks driving the same routes?
-Are they driving in the same climates?
-Are they pulling the same weights?
-Do the trucks have the same aero package?
-Do the trailers have the same aero package?
-What do the ECM's say about driving habits?
-Does the red top have a bunk heater while the other guys idle all day every day?
-How are you figuring the mileage?
-Are they fueling at the same places?
-How are you keeping track of fuel purchases (possible two drivers are stealing fuel)?
-Does the red top have old rubber?
-lugs?
-open shoulder lugs or closed shoulder lugs?
-What are the transmissions?
-What is the gearing?
-What are the tire sizes?

 

Have you ran these in warmer states? Last 2-3 weeks my truck dropped down from 6.7 to 5.4. Mostly because of the extra cold.

 

For what it's worth, my 2005 International 9200 had a 435 hp C-13 acert, 3.70's, 10 spd od, cheap caps on drives (always max pressure), conventional 15w-40, and perfect alignment.
I was a brand new O/O fresh out of truck driving school, always kept 63 mph, usually grossed out, and I averaged 6.2 mpg. The absolute worst was 5.5 mpg, 80k lbs, strong headwind for 370 miles, sub-zero windchill, and running a 70/30 blend.
I had nearly zero idling thanks to a rigmaster APU that always got started as soon as I parked. (Still uses some fuel)
The best mpg was 8.2 mpg, 8k lb load, no wind, warm weather.
My engine was drinking oil (no leaks).
IIRC, 63 mph was about 1600-1650 rpm on 22.5 lp's.
I would suspect a non-mechanical problem...