Best MPG grossing 117,000 pounds

I'm sorry but at that weight a big bore will get better mpg and you'll be pushing the 12.7 to its limits all the time. 3.90 is a great setup for those weights and 4.11 if your in the hills all day

 

True

 

You're right in the ballpark for the big bores, the 12.7 may need 4:30's on low rubber to compete in the hills.
If you check the CDN truck dealers that spec for Super B's, which pull around 135,000 lbs, you'll see that 3:90 and 4:10 are the most popular ratios, with tall tires, 15 liter engines and 18 spd trans, Paccars mostly ISX's @ 565 hp & 1850 ft/lbs, seems to be the most common spec.
I'm thinking you might get away with a 3:70 or even a 3:58 at 117,00 lbs, depending on terrain.
If you're in the hills or mountains all the time, not a good set up, would do a lot of unnecessary shifting.
I pulled trains across #17 in N Ontario regularly in the late 70's, (lots of hills), @ 135,000 lbs with an NTC 350, 4:11 rears, 15 spd direct and tall rubber, not a rocket ship but it got the job done.
When I jumped to 445 HP with a 8V92TA and 3:90's I was ecstatic, not a huge difference in fuel mileage, when I had a "real pro" do "a proper tune up" I rose to the heavens above, but I had to drive a little differently to maintain my old average mpg.

 

Yea we have a mack with tall 24.5 and 4.42 it pulls pretty good with that setup 1600 at 65. The other one has 3.91 on 22.5 LP but i wouldn't wanna put big rubber on it

 

What rpm does your Mack like? Which engine model does it have?

 

Not only that, he can’t do it unless it’s on paper. Sounds to me it ain’t worth doing. Jmo

 

93 E-7 with inline Bosch pump and 99 with EUP's. 1450-1600 is the sweet spot. The older PLN's are smoother and have less issues overall

 

You are correct,sir.
The money would have been to be obscene to run that heavy full tilt. When money is obscene, you don’t have any time for beancounting.

 

He claims it's by ten minutes, if he's not exaggerating real horribly there there would be no other way to do it, no matter how good or bad the money is.

 

It’s a recipe for disaster. Trying to run that fast, that heavy pushing the clock every day. Do a load and a half a day and price accordingly. No point in running your dick in the dirt for two extra loads a week