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Fuel and Gas Saving Tips - Conservation Of Energy

35 Fuel Economy Tricks From Tractor-Trailers

David Kennedy
Oct 1, 2008
Contributors: Jason Thompson
Photographers: Jason Thompson, Courtesy of Michelin, International
Photo 2/12   |   fuel And Gas Saving Tips corvette Racing
Hard times give charlatans offering snake oil easy prey. On the bright side, absolutely real solutions are forged from the stress and heat radiating from tough situations. Diesel Power jumped into the swamp of fuel efficiency and sifted the kernels from the chaff. The conservation of energy is an idea that, once mastered, is basically an mpg truth detector. Diesel fuel has a potential energy between 128,700-140,000 British thermal units (Btu). One Btu is the amount of energy needed to heat 1 pound of water 1 degree F. There are an infinite number of things you can do in order to get the most from this finite number. The most efficient heavy-duty diesel engines only use 51,480 Btu per gallon. This article pulls much information from the more advanced world (at least when it comes to the conservation of energy) of heavy-duty diesel technology. Let's apply tractor-trailer ideas to the realm of consumer diesels.
Photo 3/12   |   Replacing the engine's mechanical fan with electric cooling fans has been shown to increase horsepower and fuel efficiency because the engine no longer has to spin the huge cooling fan all the time.
Fuel Economy Tips From Tractor TrailersInternational creates 436,000 diesel engines a year. Check out what it recommends to improve fuel economy. Remember, the first 22 tips are tractor-trailer specific, but with a little creativity they can be modified to our core segment. Here is a compiled list of fuel saving ideas from a profitable medium/heavy truck manufacturer:
1. A worn tire is about 7% more efficient than a new tire. The break-in period for tires is between 35,000 and 50,000 miles.
2. Every 10 psi that a tire is underinflated reduces fuel economy by 1%.
3. Tires make the biggest difference in mpg below 50 mph. Aerodynamics is the most important factor over 50 mph.
4. Idle time is costly. Every hour of idle time in a long-haul operation can decrease fuel efficiency by 1%.
Photo 4/12   |   fuel And Gas Saving Tips m And Ms Truck
5. Above 55 mph, each 1-mph increase in vehicle speed decreases fuel economy by 0.1 mpg.
6. The most efficient drivers get about 30% better fuel economy than the least efficient drivers.
7. Aerodynamic treatments can reduce the horsepower required to move the truck by 30 to 35 hp.
8. Every truck does not have to be fitted with all the aerodynamic features available. For example, if the vehicle is only used for local deliveries, it does need air dams designed for highway use.
Photo 5/12   |   Correct tire pressure is critical to get the most from your tank of fuel.
9. Every 2% reduction in aerodynamic drag results in approximately 1% improvement in fuel economy.
10 The rpm level where the engine cruises can provide critical fine-tuning of fuel economy. To do this, you can spec the axle gearing so that the engine runs at its torque peak.
11. All oil thickens at low temperatures, causing increased fuel consumption. Synthetic oil is less affected by temperature, thus making it more fuel-efficient.
12. Tires flex more at higher speeds. This leads to more friction, higher tire temperatures, and reduced fuel economy.
Photo 6/12   |   Michelin X One tires are more fuel efficient than a traditional dual-tire setup. They also look cooler. When shopping for a truck, remember dual rear-wheel setups are less fuel efficient than single rear-wheel models.
13. Rolling resistance results from the internal friction of a tire as it deflects (flexes) during motion. Energy spent generating heat in the tires is energy that does not contribute to moving the vehicle. Cooler running tires are more fuel-efficient than tires that run hotter.
14. Air conditioner power demands are relatively small compared to the cooling fan, but every little bit helps so drive with the A/C off.
DP Diesel Power Note:
Although lighter duty diesel engines don't have air brakes, they do have A/C compressors and other accessories, which should be inspected to see if they spin freely.
15. Exceeding the recommended engine oil levels can lead to significant oil churning/spin losses, resulting in reduced engine efficiency and mpg.
16. It takes between 10 and 70 hp to drive the cooling fan, so cooling system maintenance can have a significant effect on fuel economy.
DP Diesel Power Note:
Replacing the stock clutch fan with a Flex-a-lite twin electric fan setup is said to recover 27 hp and increase fuel mileage by 6%.
17. A tire that is misaligned only 1/4-degree from straight will try and travel 10-15 feet sideways for each mile, resulting in lower fuel economy.
Photo 7/12   |   Removing the front driveshaft is an option on vehicles without lockout hubs. This modification will increase mpg.
18. Selection of the appropriate drivetrain components is critical to achieving drivability and mpg goals. Direct-drive transmissions can yield a +2% advantage in mpg from lower-gear mesh losses and lower spin/oil losses.
19. Road roughness can increase rolling resistance up to 20% due to energy dissipation in the tires and suspension (10% loss in mpg). The best surface for fuel efficiency is polished concrete.
20. For every 10 mph of headwind or crosswind, mpg is reduced by nearly 13%. You cannot escape increasing wind resistance.
Photo 8/12   |   Notice this truck's extended air dam. It pushes air away from the non-aerodynamic undercarriage.
21. A list of behaviors exhibited by drivers that consistently obtain good fuel economy:* High percentage of trip distance in top gear (90+% recommended)* High percentage of distance in cruise control* Minimum service brake activity* Minimum percent idle/PTO operation
22. Michelin is offering a new X One tire for tractor-trailer rigs. Replacing the dual-tire setup with one extra wide tire is said to increase fuel efficiency 5%. A tractor with duals has a total wheel and tire weight of 2,704 pounds, whereas when fitted with the wide X Ones , the total weight is only 1,963 pounds. The X One tires turn much easier than a set of duals because the duals are fighting each other anytime they are not going perfectly straight.
Photo 9/12   |   Be careful when spending money to save money. Additives and fuel saving devices should come with a written guarantee that backs up their claims.
DP Diesel Power Note:
Which staff member at Diesel Power has the most fuel-efficient foot? Stay tuned to find out.
23. Don't Keep Tank Full
Remember that diesel fuel weighs about 7 pounds per gallon. Vehicles have a tendency to nickel and dime their owners to get some revenge and make every pound count. Remember the straw that broke the camel's back.
24. Remove Front Driveshaft
This easy modification drops the vehicle's weight. It also makes for one less moving part on vehicles without lockouts. When winter comes or if fuel prices drop, put it back on.
25. Locking Hubs
Disconnecting the wheel from the axle with lockouts will improve .4 mpg.
26. Live On the Edge and Ditch the Spare
This option will become more real once run-flat tires become an option for consumers. Still, tires today are so good the spare rarely gets used. We would guess that 3 times out of 10, the vehicle's spare tire doesn't have air in it anyway. In its place, have a few plugs and an old-fashioned hand pump. Craftsman came out with a 19.2 volt handheld air pump that inflates low-volume tires up to 200 psi. As for plugs, the ones from Napa are much better than the cheap ones. There is a big difference.
27. Look To Racing
Now is the perfect time to upgrade to fiberglass fenders. Why stop there when you can spring for a carbon-fiber hood? With fuel at the prices they are, one can't afford not to.
Photo 10/12   |   The problem with air dams is they get ripped off when off-roading. An adjustable or hinged air dam might be a solution to this problem.
28. Lexan
Replace as much glass as possible, although be sure to leave the windshield alone. Imagine what would happen if every pickup and SUV would replace just one piece of glass with this welterweight material.
29. Aerodynamic Tricks
Air dams and tire skirts push air away from un-aerodynamic areas. Early Broncos and many other cars from the '50s and '60s used tire skirts. With everyone's attention focused on fuel consumption, we might see this retro styling return.
30. Manual Trans Swap
When shopping for a used truck, avoid three- and four-speed automatics, and seek out five- and six-speed manuals so your engine can stay in its torque peak.
Photo 11/12   |   fuel And Gas Saving Tips ford F350 Dually
31. Radiator Relocation
The mud-bogging crowd has done this trick. With the radiator by the tailgate, the front could be totally blocked off.
32. Diesel Reinforcements
Propane, compressed natural gas (CNG), and hydrogen are alternatives in supplementing diesel.
33. Remove All Traces Of The Air Conditioner
This will make it cleaner under the hood and create less load on your engine. Many serpentine belt systems can be routed with the compressor removed-all that is needed is a shorter belt.
Photo 12/12   |   fuel And Gas Saving Tips ford F250 Off Road
34. Lower The Truck
If you want big tires, get out the saw and cut the sheet metal. Don't lift your truck anymore than you have to.
35.Fuel Connoisseur
Don't fill up when the tankers are filling the tanks. Let the fuel settle before putting it in your truck.


Department of Energy
Michelin North America
Greenville, SC 29602
Navistar International
Fuel Economy.gov