MPG loaded, m915 vs M916 vs M920 ?

I was trying to figure a few things out, and I wanted to try and compare mpg on the trucks, as close to apples to apples as it could get.
Loaded, being around 80k gross (or more, but 80k for a solid comparison.)
And the 915 could be the older with the cat 7155 transmission and the A1 with the auto.
I know there are a few out there that have the 7 spd double OD setup, but those are not common enough yet.

Now, I know the numbers you guys will have will be with different trailers, different roads/hills, etc. But I know a few of you have more then one of the above, so could give a decent comparison of mpg differences between the trucks.

The following probably doesn't answer any of your questions.

Unloaded M915A1, foot to the floor (62-ish mph, little red light in the tachograph glowing), summertime, moderately inclined interstate: 7 mpg.

Andy

m920 5 mpg

Soni, said he got 3.5ish on his return trip from the M820 recovery.

He said he was pushin a head wind and not paying attention to his foot... but I wouldn't expect good numbers from any listed loaded.

We are talking about moving thousands of lbs...this isn't a Prius.

Bighurt said:

Soni, said he got 3.5ish on his return trip from the M820 recovery.

He said he was pushin a head wind and not paying attention to his foot... but I wouldn't expect good numbers from any listed loaded.

We are talking about moving thousands of lbs...this isn't a Prius.

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If I'm not mistaken, I think Hammer is looking to get one to use commerically. I would suspect his compairing MPG vs Civy tractors.

Josh said:

If I'm not mistaken, I think Hammer is looking to get one to use commerically. I would suspect his compairing MPG vs Civy tractors.

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3.5 isn't bad for commercial heavy haul either.

My buddy hauls a 53' grain hopper, and he averages 4.5mpg loaded.

The average commercial truck on the market gets about 7mpg.

Again thousands of lbs, rolling down the road.

I used to complain about my F350 but I get better mileage than the wife in her F150...

When I want to save money, I walk or ride the motorcycle.

But even the motorcycle gets worse mileage if you consider fuel used to move 1 lb of weight 1 mile. Sure it gets 30 mpg but it's moving 400 lbs. My truck gets 17 mpg but it's moving 8400... vs the M915A1 that gets 7 mpg and weighs 20000....

Yeah, Josh has it right.
I KNOW about running an 80k load.
I know about mileage for big rigs.
I figured the M915 should be fairly close to most of the trucks of that time. Between 4 to 6 mpg loaded, depending on circumstances.
But I wasn't sure what the auto in the A1 would change it to, and how the 916 and 920 would do with the live front axle, plus a bit more weight to them.

Soni's isn't much of a comparison though, he has a newer, and much more powerful engine, and a nice 18 speed transmission.
That does seem a bit low though. I guess it is about the rpm running on the freeway. It doesn't take much more rpm to really suck down the fuel.

The M915 was designed to be a line haul tractor for moving general cargo over various terrains (mostly improved roads) and road conditions.....no transfer case or front wheel drive.

The M916/920 were designed to travel mostly on rough terrain while hauling heavy equipment on flatbed trailers. They have transfer cases, front wheel drive, big winches on back, etc and are geared lower (for the most part) than the M915. To top it off they have the aerodynamics of a concrete block.

You are never going to get fuel milage comparable to a civilian vehicle with any one of them. You may do fair with a M915 but anything bigger is going to suck fuel. It is the nature of the beast.

Soni's truck does not have a stock engine/tranny/gears so there is no comparison with his.

I don't expect to get great mileage like the newer stuff.
But I was asking to see what people WERE getting. I know there are a number of these trucks being used fairly regularly to haul some pretty heavy loads.
I have a few ideas for using them that would make them a nice starting truck for an owner/operator. I was just trying to figure out the numbers based on MPG.
And most of what I would want to do, the rough terrain part of these trucks would be a very nice bonus.

can you get m915a3's yet? Because if so, those are basically just camo freightliners no?

I think the M915A2 is the biggest step up, with the detriot 60 series. Can't remember which transmission it has though.
Doesn't really matter though, as neither of those are really available.

I understand that these trucks will get less mpg. I just wanted to know how much less, to see if it would offset the costs of truck payments, etc. Within a small percentage, the mpg loss is well worth the low startup cost, and the rough terrain capability these trucks offer. But with enough miles, that fuel bill can really start adding up!

wreckerman893 said:

The M915 was designed to be a line haul tractor for moving general cargo over various terrains (mostly improved roads) and road conditions.....no transfer case or front wheel drive.

The M916/920 were designed to travel mostly on rough terrain while hauling heavy equipment on flatbed trailers. They have transfer cases, front wheel drive, big winches on back, etc and are geared lower (for the most part) than the M915. To top it off they have the aerodynamics of a concrete block.

You are never going to get fuel milage comparable to a civilian vehicle with any one of them. You may do fair with a M915 but anything bigger is going to suck fuel. It is the nature of the beast.

Soni's truck does not have a stock engine/tranny/gears so there is no comparison with his.

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Richard is right, the aerodinamics on those trucks suck....It does not make much difference up to 55MPH, but anything above that makes the MPG drop fast.
Also, what lowered the milage on my return trip was the fact that I was at almost 80,000#, had severe head wind, had a load that resembled a 14' by 8' "barn door"and I have also found on past trips, that the 3 axle lowboy has much more rolling resistance then the 2 axle M270A1. It makes almost a 1MPG difference between the two under the same load and speed conditions.
Further imparing my milage on that last 3.5 MPG tank was the fact that I had to leave the truck running for six hours that night because of the starting issue.

One additional fact that I think makes a difference on the MPG is that with the truck on cruise control, you loose the feel on how much throttle is needed to maintain the set speed. This keeps you from letting it slow down some in like bad head wind.
You just don't realize how hard the engine is working, until you look down at your boost gauge, and it shows 38# boost on almost level road....


Anyway....normally I get between 5.5 and 7 MPG with an empty trailer or bobtailing and between 4 and 6MPG loaded.

Soni

I have checked my 915A1 several times,empty or loaded it gets about 5.5 mpg or about 550 miles to the fill up,I have not noticed any difference grossing 70 to 80K vs running bobtailed,other than quicker acceleration.

It's not overfueling,very little black smoke on takeoff or pulling hard,rebuilt PT pump and I have adjusted the valves,injectors and Jakes as well as serviced the trans and diffs.

I usually run it at about 2150 rpms or so down the interstate netting me about 57 to 59 mph.

Thank you guys! Empirical data to work from.
I figured it would be easy to run 80k with the 915, but if I got the 920, then I can bump the GCWR up to 105,500. Figuring that the mpg will drop with the added weight and axles, etc, I was trying to figure out if it was worth it, and could I still make money that way.

Of course with the price of these trucks now going through the roof compared to a couple months ago, I fear I missed the bandwagon for getting these trucks 'cheap'...

firefirefire90 said:

can you get m915a3's yet? Because if so, those are basically just camo freightliners no?

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Yeah....915A2 and 915A3 are Freightliners.....A3's have the 6 speed push button Allison tranny! Don't know if they are being sold yet....

Soni

Hammer said:

Thank you guys! Empirical data to work from.
I figured it would be easy to run 80k with the 915, but if I got the 920, then I can bump the GCWR up to 105,500. Figuring that the mpg will drop with the added weight and axles, etc, I was trying to figure out if it was worth it, and could I still make money that way.

Of course with the price of these trucks now going through the roof compared to a couple months ago, I fear I missed the bandwagon for getting these trucks 'cheap'...

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Hammer,

the GCWR on the M920 is 152,000# according to the book. Of course this is all "permit country" and depends on the State your hauling in....

Most states it's a permit above 80,000# on 5 axles. Some States let you buy a permit to go up to 108,000# on 5 axles, but then if you go above that it goes back down to the "Bridge Formula"....in other words by how many axles you have and the spacing between them. For example in most States you can get 20,000# per drive or trailer axle and 36,000# for a tandem. If the centers of the tandem are more then 8' apart (some States it's 10') you get 20,000# per axle or 40,000# total. Thats the reason for spread axle trailers....

Soni

M920 said:

Hammer,

the GCWR on the M920 is 152,000# according to the book. Of course this is all "permit country" and depends on the State your hauling in....

If the centers of the tandem are more then 8' apart (some States it's 10') you get 20,000# per axle or 40,000# total. Thats the reason for spread axle trailers....

Soni

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You mean tire eating trailers don't you? I have friends that haul rolls of coil stock using aluminum trailers and they average 25K miles per set of trailer tires.

Maryland until the late 90's limited the maximum weight to 73,280 unless overwirght permits were purchased.

Every spring to early summer the guys hauling water mellons would get stopped by the Maryland State Police rookies for inspection, weighing and then unloading to get to legal weight. I forgot to mention the hugh overweight fine. After a while it became comical to be passed by someone hauling produce in a open sided trailer flying low only to be caught up at the scales.

Soni, here in WA (and OR, ID and MT I think.) 105,500 before permits, but it is all based on bridge weights above 80k.
Of course the cost of registration goes up drastically above 80k.
So it is the drop axle part that ups the weight for me, otherwise the 916 could technically have the same 105,500 gcwr.
Only problem is the weight of the 916 and the 920. With the winch, hydraulics and front axle, it really makes for a lot more weight then a civvy OTR tractor.
Personally, I was thinking about taking the winch off, and saving that for setting up on a trailer, and keep the pto on the tractor to run as a wet kit setup.

I was trying to figure out if it was worth it, and could I still make money that was.

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Using one of these trucks to make money is a hard row to hoe. They are spartan at best in the way of creature comforts. You can add air ride seats and AC and improve the ride some.

I drove a M916 from Fort Benning, GA, to Fort Chaffee, AR, and back hauling a D8 dozer one time. By the time I got back to Benning I had had about as much of that as I could enjoy for one month.

They ride like an oxcart and there is not a lot you can do about it. Even with a heavy load they will still jar your teeth out when you hit a bad chuck hole in the road.

If you are going to do short haul or permit loads where you are in a motel every night it prob isn't a big deal. You will have to run a log book and if you don't have a sleeper you will have to prove to the DOT that you are getting the proper rest breaks. They can put you "out of service" if they think you are fudging the paperwork.

Just my input for what it is worth.

using m915a1 and m920 for hauling corn/soybeans........ 120 miles round trip. 80000 lbs m915a1 full/30000 empty getting 4.5 mpg average trip.....88000 lbs m920 full/37000 empty getting 3.85 average trip...