Power or Speed

Its kinda hard to a one size fits all but I run a 565 x15 cummins with an 18sp 3.58 rears and 11r22.5 at 105,500 here in the northwest area and it seems pretty well balanced. 1400@65mph pulls the 4-6% hills at 28-35mph avg 5mph with a 388 peterbilt and tanker trailers but have kinda high idle hours due to pto pump offloads.

 

If you're going to run in Ontario you're required to have the speed limiter set at 65 mph.
So knowing that you should gear your truck for peak economy at 65 mph like most trucks have been geared to do for the last 40 years or more, at least in Canada.
You can disable the limiter or bypass it, I think, pretty sure that's been figured out already.

If you're going to run around with a half loaded trailer then 450 hp with a 10 spd that runs at peak efficiency at 65 mph is all you need.

If you're going to run with a full jag all the time over most of the continent, I recommend you look in the 500 to 550 hp range, look at the power curves for all of them and find the one that suits your needs or driving style, put a 13 or 18 spd behind it and I recommend 24.5 rubber, just a preference based on my own experience.

With big rubber a 3:55 or 3:70, should be a good all around gear for transcontinental work and give you a fairly versatile truck.
It won't cruise at 85 mph with a half empty trailer and give good fuel economy with those gears, but it will cruise comfortably at 65 to 70 mph at 1500 rpm with 100,000 lbs plus in nearly any conditions.

If you want to be a superstar, or happen to be a real deep thinker and want the best of all worlds, then ponder this, a 2 speed differential.
Last time I looked, Eaton made a 40,000 lb, 2 spd diff with 3:08 and 4:88 or 4:63, I think, can't remember.

According to the road speed calculator, on tall tires you had 3 gears that you could cruise at 65 mph within the engines peak economy range and a real going home gear.
You wind up with a truck that will hit 100 mph, be able to play in the dirt and climb mountains like a goat.

Speed doesn't matter unless you're anal retentive, have anxiety issues or want to win a race.
Overall, a steady and versatile truck is the best kind of truck.

If you don't need speed or power, just consistency, look at 450 hp at 1750 ft/lbs and consider a 15 spd OD.
Top gear is .78 I think, bit slower than .73, less of a split from direct to OD which can be and advantage over a 10 spd if geared correctly. plus you have deep reduction which is a bonus.

 

Epa10 and younger are low rpm high torque engines
Pre ELD are higher rpm.

Running at 80 000lbs gross max with EPA 10 or younger.....get a 13l.

Epa 10 or younger ,you have to check each engine seperate for it's sweet spot.

 

Cat 600 with 3;52 worked out really nice for me.

13sp.

 

Had a Cat 3406 turned to 525HP. 3:52 rears. 13 speed. Would cruise all day at 74 mph at 1475 rpm. And decent fuel mileage pulling that 48’ shiney hiney loaded up with chicken Alabama to LA.

 

My Cat is 550 with a 13 and 3.55s. Have no trouble pulling the mountains in the West at 30-35 loaded. Have been getting 6 mpg according to IFTA.

 

What's up with the '70 Duster with (CalTraks)?

 

If I had to chose, it’ll be a BXS Cat with 1,200 horses, 18 speed, 3:55 or 4:11 rears.

I find Cats are at their most efficient when they’re up around 800 hp or more. They do not like being severely detuned in my opinion.

I currently drive a 1998 Ford with a 475 hp 6TS 3406E. Has been averaging 5.5 mpg (cnd) with 4:11 gears and 18 speed.

I’m currently doing an inframe on a 2005 BXS. When that truck is finished, I’ll be back in it.

It’s tuned to 575 hp/2,050tq, 4:11 rears, 18 speed. It also averaged 5.5 mpg with B-trains.

 

I was happy with the old M11 Cummins or the 3176 Cat,,, less that 350 hp.. worked well in the midwest and still stayed around 9 mpg.