I'm trying to decide between aluminum or steel for a new stock trailer. With my present setup, I'm not noticing a big change in mileage between having two horses on the trailer and being empty. Yet theory says that the more weight, the lower than the fuel mileage. So I guess my question is whether there are any engineering studies that show how much an additional 1,000# cost in mileage?
Certainly weight is going to make a difference. How much, I don't know. It has been my experience that drag makes a bigger difference. In talking with other drivers, I find they get similar milage to myself hauling a high profile 5th of similar size but half again as heavy. The guys hauling more weight in a horse trailer will do far better. 20 to 30 percent better.
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Here's a couple examples that might help you decide.
This past summer I made a 7 state pull to buy a couple ag-tractors.
At 15kGCW empty flatbed trailer I pulled just like I did my 28ft RV at 16kGCW. Fuel mileage was figured ruff at about 1mpg better with the empty flatbed only because it was all flatland pulling vs all mountian pulling on my RV, so that's a wash. My driving style, ie; shift point rpm etc:, was the same pulling both trailers. My truck weighs 8K.
I then loaded on one tractor for 26kGCW. My driving style remained the same as pulling my RV. Fuel mileage dropped slightly by about 2mpg. I keep accurate overall trip fuel mileage but ruff intermediate mpg as I have a aux tank. Sure the load pulled slightly harder than my RV but just not that much difference. This really surprised me.
I then loaded another tractor for 31kGCW. That was a huge weight increase for this truck and I had to change my driving stlye to use full turbo power or 2200rpm to 2500rpm to maintain 50mph to 60mph about 50% of the time as I was also fighting a 30mph headwind. Fuel mileage took a huge hit at a 4mpg loss.
From that I can't see a benefit if your under 26kGCW or so. You might save 1mpg for 3klbs of additional weight, but that would be about it with a PSD. For the cost difference I'd by a steel trailer.
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T_Bone
02 F350, 4X6, Crew, DRW, LWB, PSD, 6spd, 3:73, Island Blue, Stock, AEB2, Phoenix Az
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I think the biggest mpg eater is parasitic drag. When I haul a vehicle on my (Steel) 16'car trailer I get just over 10mpg, When I haul my (steel) 26' 3h gooseneck w/horses I get 12.8mpg with the g/n combo weighing in about 1000lbs more.
Also I believe theres only about a 20% weight savings with going aluminum over steel as it takes thicker aluminum to match (thinner) steel strengh ratings.
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2000 F-250 PSD,SC,SB, 6spd, 2WD, 3:73LS, ORU Diff Cover, Slide-N-Lock Cargo tiedowns, B & W Flip hitch, Timbren Springs, Jason topper, Diablo, 4" exhaust,Southbend clutch, AIS, FPR...M.O.U.S.E!
This isn't what you asked but, I always suggest an aluminum trailer for the following. It will last longer and look better. It will be much easier to sell and you will gain in resale value. No matter how much you keep after a steel , urin , manure, weather will eventually take their toll.
Concerning fuel cost I don't think you will notice much difference between similiar trailers made of steel or alum. I don't see much difference when I am hauling two horses or three or four.
I agree with Fieldtrailer re: buying the aluminum trailer. It will hold its value better, require less maintenance and will look better longer. Some of the better quality aluminum stock trailers that I have seen include Eby, Featherlite and Sundowner. I'm sort of partial to the Sundowners, but the Ebys are really well built and pull nice. The featherlites are not as stoutly built, and I've never pulled one, but they look like they would be good trailers.
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Let's put it this way, I used to drive tractor-trailers. Mine got about 6 mpg hauling 60 - 70,000#.
Wind resistance is a bigger factor than rolling weight at highway speeds. Most of the work is getting the weight rolling, after that there isn't much to keep it rolling on flat ground.
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1985 International rollback, 6.9L 5 speed "Li'l Big Truck"
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I'm trying to decide between aluminum or steel for a new stock trailer. With my present setup, I'm not noticing a big change in mileage between having two horses on the trailer and being empty. Yet theory says that the more weight, the lower than the fuel mileage. So I guess my question is whether there are any engineering studies that show how much an additional 1,000# cost in mileage?
Jim Clark-Dawe
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On the level, multiply the difference in weight by the rolling resistance (probably around 0.01) by the speed by the specific fuel consumption. (probably about 0.5 lb/hp/hr)
For 1 klb and 60 mi/hr:
1 klb * 0.01 = 10 more pounds pulling force
10 pounds * 88 ft/s = 880 ft*lb/s (1.6 Hp)
1.6 Hp * 0.5 lb/hp/hr - 0.8 pounds per hour
(life would be a lot simpler if we used a consistent set of units, but that's covered in the "Metric System Adoption - Why Not?" thread)
If you're cruising at 28 pounds per hour, that additional 0.8 lb/hr is about an additional 3% fuel burn.
On a grade, add the previous result to the power required to drag it uphill - slope * weight * speed.
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Douglas Campbell [drcampbell ot engineer dat kahm]
November 5, 2008: The fat lady sang. Back to actually working for a living.
1986 Isuzu P'up, 177,673.8 miles. Hella headlights, (highly recommended) DOT C-2 back end. (also recommended) R-12 air conditioner converted to R-406a. 4.1:1 rear axle converted to 3.4:1.
9/22/2007, age 21: Still running well when reluctantly sent away for reincarnation, due to body & frame rust.
Here's a couple examples that might help you decide.
This past summer I made a 7 state pull to buy a couple ag-tractors.
At 15kGCW empty flatbed trailer I pulled just like I did my 28ft RV at 16kGCW. Fuel mileage was figured ruff at about 1mpg better with the empty flatbed only because it was all flatland pulling vs all mountian pulling on my RV, so that's a wash. My driving style, ie; shift point rpm etc:, was the same pulling both trailers. My truck weighs 8K.
I then loaded on one tractor for 26kGCW. My driving style remained the same as pulling my RV. Fuel mileage dropped slightly by about 2mpg. I keep accurate overall trip fuel mileage but ruff intermediate mpg as I have a aux tank. Sure the load pulled slightly harder than my RV but just not that much difference. This really surprised me.
I then loaded another tractor for 31kGCW. That was a huge weight increase for this truck and I had to change my driving stlye to use full turbo power or 2200rpm to 2500rpm to maintain 50mph to 60mph about 50% of the time as I was also fighting a 30mph headwind. Fuel mileage took a huge hit at a 4mpg loss.
From that I can't see a benefit if your under 26kGCW or so. You might save 1mpg for 3klbs of additional weight, but that would be about it with a PSD. For the cost difference I'd by a steel trailer.
I'm gonna ride along with Tbone on this one. I've put over 3,000 miles on the truck in my sigline since purchasing it....running unloaded, with no topper, with an ugly windcatching topper, a more aerodynamic sleeper, dragging and empty and loaded carhauler....you name it. Doesn't matter as I've been getting 14/15 mpg in every situation.
Appears to me that up to a certain GVW/GCW, mileage is more a matter of a vehicle's efficiency potential relative to it's power unit, driveline, axle combo and driver's driving style than anything else. Then, once you add weight that exceeds that potential mileage begins to deteriorate. Simply, the total configuration of my truck along with how I personally drive it, and so far up to a GCW of say 14K#, it will get 14.9 mpg.
This info and theory is relative to a diesel powered vehicle. With respect to my gas powered trucks, their efficiency potential was pretty much exhausted just moving the mass of the vehicle alone and, the more weight I added, the worse the gas mileage. The exceptions were 7.4L Vortec GMs....I got 12 mpg empty and pulling a trailer up to 13K GCW.
My last OTR truck driving job was pulling straight tube tanks with a cabover KW w/Cummins big cam 350, 13-spd, and 3.90 rears. Fuel mileage was 8 mpg loaded and 9.5 mpg deadhead. I had to bobtail 400+ miles once and out of curiosity I tanked it up afterwards and it got 10 mpg.
EDIT: Oh....of all the aluminum trailers in my experience, after a couple of years we had to break out the welder and constantly check/tighten fasteners to keep them together. Never such problems with steel units.
Comments?
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Also I believe theres only about a 20% weight savings with going aluminum over steel as it takes thicker aluminum to match (thinner) steel strengh ratings.
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Not true.
Aluminum alloys have a much stronger yield strength than steel. The common steel alloys (C1010 & such) exhibit much smaller yield strengths, but much more toughness and ductility.
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2005 F250 Lariat FX4 Crew Cab. NO MODS = NO PROBLEMS. (Approx: 45k miles) Shaker 500!
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On the level, multiply the difference in weight by the rolling resistance (probably around 0.01) by the speed by the specific fuel consumption. (probably about 0.5 lb/hp/hr)
For 1 klb and 60 mi/hr:
1 klb * 0.01 = 10 more pounds pulling force
10 pounds * 88 ft/s = 880 ft*lb/s (1.6 Hp)
1.6 Hp * 0.5 lb/hp/hr - 0.8 pounds per hour
(life would be a lot simpler if we used a consistent set of units, but that's covered in the "Metric System Adoption - Why Not?" thread)
If you're cruising at 28 pounds per hour, that additional 0.8 lb/hr is about an additional 3% fuel burn.
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The above math agrees with my opinion of what weight does to fuel mileage. If empty my mileage is 13 mpg, adding 1,000# of weight decreases my mileage to 12.61, ignoring grades. Another way of looking at this is that is takes 75.9 gallons of diesel to travel 1,000 miles empty and 79.3 gallons of diesel to travel the same 1,000 miles with a 1,000# on the trailer. This works out to a whopping 2.4 gallons of diesel per 1,000 miles per 1,000# of weight! Or in dollars and cents, about $7 at $3.00 per gallon for diesel.
This formula appears to be constant, so that an additional 1,000# (bringing cargo weight to 2,000#) should only reduce my mileage by approximately 6%, meaning that if I add a ton to my trailer (from empty), I've only increased my fuel cost to about $15 from hauling empty for a 1,000 mile trip.
So I guess my reaction is that any weight savings for an aluminum trailer result in minimal savings at the pump. Based on these figures, saving 1,000# of trailer weight would save me $70 over 10,000 miles and $700 over 100,000 miles. It looks like the payback for fuel savings of buying an aluminum trailer is somewhere around 500,000 miles ($4,000 price difference). So the idea that an aluminum trailer is going to save money at the diesel pump just doesn't work out when you run the numbers.
My cousin is the terminal manager for a specialized flat-bed transportion company in Florida. The only pull flatbed trailers.
The management of his company several years ago decided to spend the extra $$$ and buy only aluminum trailers and have since converted all their fleet to aluminum trailers. As a salesman for one of the big 2 aluminum companies, I was eager to see how they turned out.
He said their profitability went up enough to much more than cover the extra cost of the aluminum trailers....because they could haul heavier loads before maxing out for the D.O.T. He said their MPG went up slightly when coming home for a dead-head, but that was not the big money-maker for them.
I suspect the more hills you have to climb and go down, the more pronounced the savings would be.
Florida Ed
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2001 7.3 F-350 Dually Lariat CC LWB 4X2 Dark Green 4.10 4R100 5'ver Hauler (32' Montana 2 slides 10,500# - 2,000# tongue weight), 106 gal aux tank, 112K miles, nephews arguing over who will inherit it 'cause I'm gonna' drive it 'til I die. Bone stock.
2001 5.4 Gasser F-250 XLT Crewcab SWB 4X2 3.73 4R100 67K miles headed to 150K (wife's vehicle on the "junk-iron" theory of vehicle safety....most junk iron wins in a crash) stock as the day it was made
Before these: '00 F-250 CC PSD, '97 F-250 CC PSD, '94 Ford F-150, '91 Ford E-250, '81 Ford E-150, '66 Ford F-100 (cars not included)
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...
The above math agrees with my opinion of what weight does to fuel mileage. If empty my mileage is 13 mpg,...
Jim Clark-Dawe
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Hi Jim,
If I only got 13mpg empty, I would seriously consider retraining my right foot. [img]/ubbthreads/images/graemlins/biggrin.gif[/img]
My empty mileage= 19.2mpg each and every tank.
My 15k miles life time fuel mileage is 17.1mpg that includes pulling 16kGCW for 6k miles.
My 23k miles life time fuel mileage is 15.2mpg that includes 6k miles of pulling 16kGCW and 3kmiles of pulling 31kGCW. It was that one long heavy trip that knocked my fuel mileage down.
The DBW (drive by wire) PSD is very sensitive to driving stlye to yield the best fuel mileage.
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T_Bone
02 F350, 4X6, Crew, DRW, LWB, PSD, 6spd, 3:73, Island Blue, Stock, AEB2, Phoenix Az
Buy UNION work UNION. It pays off in the long run Define Union: A labor Union is nothing more than united workers with a common goal for better working conditions.
We all are in some sort of labor Union, some are just larger than others with better working conditions!
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