Reliability of Paccar MX-13 vs cummins X-15, what do you think?

To a point yes that is true and you can force a driver to get better mileage sure. And in a case where you have many drivers and many trucks it can sense. However, ive found using those devices while i was exparmenting my first year to find the correct ballence and well.....more or less flailing around. I found i on average ended up losing much more money then i saved in fuel. Sure i may save 50 or 60 gallons a week keeping to 60. But if im losing a $1500 load or two every week to keep that 50 or 60 gallons....its a moot point and i lose money on the back end. Someone with multiple trucks. Well just send an extra truck. I dont have that option. If i lose that load on MY truck. Its gone. And while i usually run at around 65-68 when i need to i have zero qualms booking it at 75 where legal to get where i need to be getting.

Most of those fuel savers amount to basically "slow down" which has its place. But for a 1 man band, i cant compete with bigger carriers on low price, capacity or number of loads. I only got speed and service as my niche. So in my use case. Using them hurts vastly more then helps thus limiting my options to use them. Its one of the big reasons why so many of us O/Os are pitching a fit over the speed limiter mandate. Not the only or even main one, but a big one regardless.

Also as for gearing, yes but also no. Ive not had a lot of experince with them in my own rig for the simple fact i have 1 rig and cant afford several gear changes so im stuck with what i got. Namely a 455/1650/3.28 mess it came with for now. So what i say is ancidotal.

With the above in mind a LOT of what i have seen in this line of work however are many rigs playing with that type of very low gearing high torque and loading them up to max gvwr constantly in poor conditions. Is many of them ending up with either blown motors from lugging trying to get going on hills or blown diffs from over stress. Also a lot of people with that setup in my field who end up complaining how often it breaks then switching to a better ratio...or going bankrupt. Something that a fellow end dumper @motocross25 if he will let me drag him in here (sorry for the tag mate) can likey corroborate with all them megas trying to get their foot in the door and blowing up trucks constantly.

The biggest thing that REALLY hurts me though is having to more or less slice off most of my aerodynamics. Roof ferring went so i could fit in many work zones and under towers, side skirts went because they kept getting damaged and finally broke for good trying to slog though poor conditions like deep mud. I run on off road tall tires so i have clearance and grip in favor of road tires with better mpg.

I use steel where ever i can so i dont break stuff such as say rims jumping curbs into construction zones cutting into my weight. I gots my giant bullbar to protect from critters....and stray hondas texting on their #### phones. I have run with the top open after a washout to dry the interior of the trailer so i can get loaded with powders and so on.

A LOT of that stuff has pretty drastic effects on economy just by their nature. And sure i CAN still use them. But it amounts to a lot of lost loads, declined loads and/or lost time. And situations like mine arent unique. Doing specialized work like i do means nothing you use on road doing line haul is going to perform anything like you expect when you throw it into conditions usually reserved for log trucks or into remote places the megas fear to go.

 

Sorry I just now saw this! I agree with everything you said and you said it good! The company I run for has their trucks turned up higher than most, their thinking is if you’re not up against the governor all the time, it’ll reflect in better fuel mileage. And for me, it has. I have a 2021 389 with a Cummins and I’m up around 7 mpg. And I’m in the same boat as @Arctic_fox i am never but a couple 100 lbs under 80k, and seldomly under 85,000 running around in Kansas.

 

I have an 450/1850 X15 in a Peterbilt 579 with a 13 speed, 3.55 rears, and 22.5 lo-pro tires. I pull 77k through hills, 50% of my miles are loaded to 77k and the other 50% are empty at 43k.

When DHing I can get north of 9.6 MPG. Loaded it usually shows between 6.8 - 7.8, depending on my speed.