Opinions on specs for 7-13 axle setups - your dream HH truck

7 axle 132-136k lbs max GVW
13 axle 256k lbs max GVW
NOT the same animal, in fact you are trying to compare golden delicious apples to mandarin oranges.
Up to 170k-ish GVW, no A-box is required. Being close to this all the time, like Ronnie and I are, it's a luxury, not a necessity. I didn't put one in, and I wish I did. That's why I convinced Ron to go that route.
Naturally, this has an effect on final drive ratios.
Terrain makes decisions as well. Most US HHers starting out are hot to trot about double framing. It is NOT needed in MOST cases. I DO NOT have a double frame, and most guys would crap their panties at some of the he77holes I've been into. I pull 160-180 daily for a living. I don't care if you pull an aluminum flat bed with a single 50gallon fuel tank, or you pull a 13 daily; tare weight is ALWAYS a concern. It's just valued and viewed differently at different levels. We have stopped double framing our 13 axle trucks, and only do back end inserts. We still have a couple double-framers for the crap that must be done.
Horsepower and Torque
Torque is a measure of rotational force irrelivant of speed or time. 2000 ft/lbs of torque is exactly that. Put 2000lbs on the end of a one foot bar, and it will have 2000ft/lbs of torque. That simple, just to confuse you, it works the other way too...put one pound on the end of a 2000' bar (if the bar could be weightless) and it will also have 2000ft/lbs of torque. Neat trick huh?
Horsepower
Horsepower standard was created by James Watt. Yup same guy that watts of electricity comes from. It was a standard created when mechanical engines were first becoming popular. How do you explain to a farmer of yesteryear how much power the tractor has? Simple, one horse can pull a one shank plow X number of feet in one hour. This fancy new steam engine can pull a 3 shank plow three times as far in the same hour. Therefore it does the work of 9 horses (3 times the shanks multiplied by 3 times the distance = 9) so it has 9 horsepower. Thus HP is a measure of work over time, which is why HP climbs with rpm, the engine is working faster, therefore less time = more HP.
(That's why gas engines make more HP than our big diesels, way more rpm...)
HP can be calculated from torque. HP = (Torque x rpm)/5252
Now the what this all means, HP is work over time, and this is what you use to properly move mass. Relying on torque INCREASES time, thus increasing the workload stresses on the internal mechanical components, shortening lifespan. It is impossible to change this. This is the dynamic physics of an internal combustion engine.
Simple experiment. Take a square cake pan and fill it with 3" of water. Take your hand and make it flat, fingers together to make the surface area as large as possible. Now slam your hand as hard as you possibly can into the water. I doubt you can hit the bottom of the pan. Horsepower!
Now, take the same 3" of water and your hand the same profile and push your hand into the water. Yup, there's the bottom. Torque!
Now the why, the water is your oil. The pan bottom is your crankshaft, your con rod wrist pin boss, your cylinder walls. Your hand is the con rod bearing, your wrist pins, and your piston skirts on your cyl walls.
Using which one, when do engine components suffer more wear, the HP or the torque?
I know, now that it's explained it's a pretty dumb question, but that's how it actually works...do you really wanna keep lugging that engine under load, or would you prefer to let it run free?
What does all this longwinded BS mean?
Gear your truck to run at 16-1650rpm when you're loaded, particularly when you are grossing 150 or more. (It's actually when your average torque load demand exceeds 34-40%, which on average is about 150k worth of drag) Now you see why the A-box comes into play for bigger weight when it's not necessary for less weight that can safely operate at 1450-1500rpm. You can't gear a truck to move big weight propey and then be anywhere close to efficient when you run empty, the A-box gives you back that flexibility. The best of both worlds, with ridiculous under drive for dead slow backing up which is like totally awesome when you're stupid big.
I don't care what engine manufacture you salesman you talk to and what he tells you. Doing this kind of work creates torque load factors most don't understand. Physics is physics, can't change it. Using torque over HP INCREASES load factor time, creating heat that must be dissipated, and wear because of the load force duration time. The oil simply gets squished out of where you need it to be because the pressure lasts longer. It's milliseconds, but trust me, every single thing in an engine is engineered, designed, and calculated to the millisecond. (Try programming one, it will blow your mind away)

So long story short, you need to decide what you're going to do. You could spec a truck capable of pulling 13 and use it to pull 7, but it would defiantly cause tare weight issues. A-boxes and frame inserts add up quick. Then you're really a glorified 6. For 9-11 you'd be on the heavy end of the spectrum, but not too bad. But be prepared, there will be the odd load that is just that little bit too heavy because your truck is too heavy, and you'll naturally kick yourself for it.
There is NO 6, 7, 8, 9, 10, 11, 12, 13 axle truck or trailer that is optimum for the entire spectrum. It's ALL a matter of compromise. Trust me, I've put WAY TOO much time and effort into trying to figure it out.
Pick a range, and I'll gladly help you spec an awesome truck.

PS: if you know how to read between the lines, the most reliable engine with the best torque curve in the programming is actually not what the vast majority think it is...for heavy work, the 600hp 1850tq engine has the best torque/HP curve bar NONE! (I know, I have every Cal file Cmns has, and a few they don't, as well as some of the big power Dtrt ones too.)

 

Yes, I'm a nerd

No problem. I've edited my post a few times, I'm kinda in the middle of figuring out an issue, so excuse my distractions.

I was going to somewhat suggest that.
I think requests like this should be broke down into several categories, and some of them overlapping.
Example;
6-8 axles
7-10 axles
9-12 axles
11-13 axles
That way you could spec a truck that you could grow with, and not hold you back too much. And when your ready for the next step, you'll probably be ready for another truck.
Trust me, each one will be a thread if their own. As you get bigger, priorities and requirements can change quickly.

 

This post may get deleted, but I hope not.
(Try leaving it for a while and just check out the number of "Thanks" it will get)
Mod's putting this section on notice.
This is how you enter a section with a group of guys with considerable knowledge, present company excluded, and ask your questions to get well thought out and informative posts.
I'm NOT trying to ruffle feathers. Our information is valuable, and we are quite aware of it. @DarkhorseEnterprises came and asked a good question, and quite frankly, I could tell by the wording that he really doesn't have a lot of knowledge on the subject, but he genuinely has an interest to learn.
He did not come in combative and start out explaining what he thinks we just don't seem to understand. This is a shining example of how you get the advise you are seeking.
It was, is, and I expect this to be, a very intriguing conversation.
I actually look forward to hearing others thoughts on his subject.
Sincerely, an opinionated voice.

 

I can tell you that none of the trucks at the company I used to drive for had double frames and we have been upwards of 200k. The double and triple frames are more for trucks that are carrying the weight and off road applications where there is a lot of twisting.

The occasional off road tweaking is not going to hurt the frame. Now these were heavier frames. I think they were 3/8" rails. Now the cross members took more abuse than the frames.

The truck that I drove was a 254" wheelbase W900 daycab c15, 18 speed, 46k rears and a drop axle. It tippid the scales at 24,300 pounds bobtail.

 

Regular freightliner I have can't do it so I'm building an A model KW to take its place..
Detriot 12.7 565hp 1850tq
13spd rtlo w/1241 spicer
3.36 alliance rears w/ 1 locker..
295" wb 14.5k steerable drop.
Low pro 24.5s. Should do most job..

 

What are you planning to pull with it?
Unless it's 80k GVW, you're rear end choice is WAY too high, even with a single over tranny.