CM2250, fuel leak mystery, please help!!

[JMBT]

(02-01-2018 )Rawze Wrote:  

(02-01-2018 )JMBT Wrote:  ...

I will take a 871 over anything older for the fuel efficiency gains alone. The gains far outweigh long term any higher maintenance costs if you take good care of the engine.

Ya know, ...my brother usually pulls heavy 100-140K gross, but every once in awhile we will book something lighter and get to run across the country together.

The last time this happened, we were trucking from FL to AZ, we each had about 30K on so fairly light, we were running about 60-62mph, and really taking our time. Easy on and easy off the pedals. Me cruising at 1450 rpm and him at about 1200 rpm. At the end of the trip I was at about 7.4mpg overall, (per the dash) which I was happy with, and he was showing 7.7mpg (per his CAT messenger screen). Now all things considered. My truck is a bit heavier then his empty, and we all know that the dash display, and CAT messenger display are not completely accurate, he also has an 18 spd to my 10, which helps immensely with being able to be in the right gear. But I was still taken aback. His is a long hood W9, with massive air cleaners, and a huge flat bumper, pushing 20 year old technology, compared to my "aero" cab new technology Volvo.

The only thing we could come up with was with his massive horsepower and running at such a low RPM, he was just "playing" with the load. Where as I, with lack of gears and a bit heavier truck was having to work a bit on the grades.

It would be interesting to see, two identical truck chassis one with the new motor and one with the old, geared the same, driven the same, with the same load, in a real world test who would come out ahead on fuel economy. My "guess" would be tuned and driven properly, the old would be just as efficient as the new.

I just remember when I got "duped" into buying this 2250, the salesman saying, "don't worry about the cost of DEF fluid, these new motors get such great fuel economy, it will more then cover the extra cost."