In my last column, I discussed the U.S. Government's Voluntary Truck and Bus Fuel Economy Improvement Program (VTBFEIP) dating back the fuel crisis of 1973. VTBFEIP recommended several areas to reduce fuel consumption. Lets see if the same thirty-three-year-old ideas still have value:
- Steel belted radials reduce rolling resistance by 40 percent. Super singles decrease resistance additionally as well as provide mass (weight) improvements. Make sure tires are properly inflated. Proper balance of the tires is also important by reducing the amount of 'work' the tire does as well as increasing tire life.
- Improved lubricants can decrease rolling resistance two to three percent. These include ester-based lubes or ones with additives such as molybdenum, Teflon or graphite. Run your own tests to separate the flashy ones from the ones that work. Additives have been shown to improve efficiency and reduce wear and tear. Only your testing in your environment will prove the claims.
- Purchase smooth sided trailers with well-rounded corners. Fuel consumption gains for fairings is well established except knowledge of use is important. Roof fairings are only effective when used with vans. Performance is worse than before on dump trailers, flats, and bobtail. To maximize fuel efficiency the trucks/tractors of the future sport smooth wheel shirts, panels between the tractor and trailer and smooth curves on all corners. Smoothing and rounding will increase the efficiency of straight trucks and busses too.
- Improve operational techniques. Under-fill fuel tanks in hot weather (for expansion). If possible, garage vehicles in cold weather to cut fuel on start-up. Improve routing to reduce mileage. If you are cube limited, doubles will provide better fuel gallons per ton-mile. Running with full loads also improves efficiency and $/ton-mile.
- Thermostatically-controlled fans will reduce fuel use. In tests on 23 units the fans ran less than three percent of total engine hours. This can save up to 20hp.
- Re-specify engine to more closely match horsepower actually required, including turbocharged and reduced fuel engines. Consider re-powering before you are about to do any major work on the engine. Specify gear train to minimize RPM (hit the RPM sweet spot for your engine choice) at road speed.
- Lightened components will reduce fuel consumption. Consider aluminum and composites to cut weight (and increase life).
- Govern engines to limit maximum speed. Remember, wind resistance increases eight times as speed increases twice. Also, govern engines to operate at maximum fuel efficiency, which is usually near the maximum torque RPM.
- Keep vehicles maintained. For example, avoid a smoking diesel, keep air cleaners free, use a torque wrench and don't estimate torque of heads, keep wheels and axles aligned (inspect frame for alignment), keep tire sizes matched, keep tire pressure right, and adjust brakes (so that they don't drag).
- When replacing components choose ones that will increase efficiency. For example, when replacing mufflers use low back pressure units (check for dents or twists that would increase back pressure), and change to disk wheels.
- Improved driving practices can save one to ten percent of your fuel bill. These include observing speed limits, keeping RPMs down, maintaining steady road speed, gradually accelerating, shutting off engine when not in use (three minutes idling on start-up and before shutdown), avoiding overfills, and shifting as little as possible.
- Watch the fuel you buy. There are many ways fuel can disappear. It can be pilfered from vehicles, spilled, pilfered from tankage, never received, etc.). One game is to heat the fuel so it expands in the tank truck and is expanded when it is metered for delivered. Once in the ground it cools and will shrink. The delivery meter should be temperature compensated.
If we add all of the ways fuel dollars are consumed the potential for savings is dramatic. Remember that fuel consumes about 20 percent of total fleet dollars.
The right tires can improve fuel efficiency, if you follow some simple guidelines.
Consider balancing all of your tires to improve fuel economy.
Developing a truck that could meet or exceed 10 mpg when fully loaded was considered unlikely, if not impossible, just a few years back, with most trucks averaging between 5.5 and 6.5 mpg.