2017 peterbilt 389

Uprate to 550 or 605 if Cummins will let you. If not, you'll have to look to the aftermarket.

 

What size tires are on it?

 

well, what you are looking for is more power and better mpg. If you had larger tires i’d have said drop a tire size. You might have a convo with Cummins n see if you can uprate to a higher power rating.

 

Are you checking the tire pressure of the container chassis that you're pulling? Containers are the least aerodynamic to begin with. Under inflation of the chassis tires will trash your mpg even more..

 

The power issue you have several options as others have mentioned, but using more power can cost you some fuel economy unless you really watch your driving habits. I have a Pittsburgh Power Box and I am extremely happy with my engine power, but in 5 years I have never gained fuel economy because of it. I also don’t focus strictly on fuel economy like I do getting the job done. Bully Dog and other aftermarket tunes could help as well. In your operation and geographic location in the winter I wouldn’t expect much better fuel economy. Your driving habits (right foot) and routinely checking air pressure in tractor and trailers will be your biggest immediate no cost gains. Long term low rolling resistance tires and warmer weather will help. You aren’t driving an aerodynamic tractor but your trailers aren’t either so you are not ever going to do great compared to some van operations. I consistently do 4.5-4.7 in the winter and 5 or so in the warm weather with a carhauler not running in the mountains. Your challenges are different than mine, but still you have obstacles to good fuel economy.

 

You can up the power if you want, you aren't going to gain fuel mileage. You have just about the least aerodynamic truck on the road, towing an equally bad load. 5mpg is what you're going to see in that application. You might be able to get better by not hogging on it so hard on the uphills and slowing down elsewhere, but then you have to get into the time vs. fuel savings equation.

 

I’m getting 5.5-6.0 mpg with a 485/500 Cummins ISX on a 2014 Pete 388 with a 13 and I thought that was bad, but after reading your post, I guess it’s the normal. My 379 I had to sell(thank you COMMIEFORNIA), was getting 7.0 all day long with a tuned up CAT.