Truck operators are viewed as a ready market for purveyors of products that promise fuel-economy improvements. After all, fuel is the No. 1 material expense in any fleet budget.
Unfortunately, many products don’t live up to their promises and are useful only as an effective means of ridding a fleet of hard-earned cash. It’s no wonder that many fleet owners tune-out such claims and never give the products a chance.
Yet, turning a deaf ear to all mpg-improvement claims may have its price, because, somewhere in the mix, there may be products that actually do what they say. These needn’t be casualties of educated skepticism.
What these products promise can be measured, and there are scientific methods of quantifying improvements in mpg.
As the late, great Don Dawson, former vice president of maintenance, Roadway Express, Akron, Ohio, once told CCJ, “You can usually tell [what products work] without too much trouble. There are indisputable laws governing matter and energy. If something works, the results are measurable. In other words, you can’t fool Mother Nature.”
Sometimes a product’s worth can be pre-assessed by checking the validity of its premise. For example, Dawson was approached to try a device claimed to increase fuel economy by decreasing exhaust back-pressure.
Dawson obliged. “That was an easy one,” he said. “Exhaust back-pressure is something we can measure. We installed an exhaust pressure sensor and took readings with and without the device in place. There was no difference, so we didn’t buy it. Simple.”
You should be concerned not only whether a product works, however. You should ensure that the product doesn’t hurt vehicles, drivers or the environment.
Blanket insurance
With the assistance of equipment users, truck manufacturers and suppliers, the Technology & Maintenance Council of the American Trucking Associations drafted Recommended Practice RP 1115 to provide end users with guidelines on how to qualify products that claim to improve fuel economy.
TMC investigated many such products, and offers the following broad, product-evaluation guidelines:
- 1. The product must be readily available on the market.
- The product must have at least three Class 8 truck customers.
- The product must have an SAE/TMC fuel economy test run to verify the fuel economy claim.
The results report must reveal who administered the test and must provide a description of the vehicles used, any aerodynamic devices used, the vehicle speed at which the test was run and the road course used.
The Society of Engineers, and TMC jointly developed the SAE/TMC on-road fuel economy tests (Type II, III or IV), which are regarded as the only scientific, accurate and repeatable methods of evaluating products that claim to boost fuel economy.
Many such products come with official-looking test results from credible laboratories showing that the products work. But while laboratory testing has its place, a laboratory isn’t a truck on the road. A measurable reduction of friction or an increase in combustion efficiency in a laboratory doesn’t necessarily translate into an on-road fuel-economy improvement.
The Type IV test (see page 36) has emerged as the most desirable for most fleets, because it allows them to haul freight – hence produce revenue – during the test. However, some find the more involved Type II and Type III tests to be more precise when dealing with very small differences in fuel economy.
“We used a Type II to test some NASA-designed, trailer aerodynamic devices,” says Duke Drinkard, vice president, field maintenance for Southeastern Freight Lines, Columbia, S.C., and one of the TMC validators of Type II testing. “We were measuring down to one-tenth of an ounce of fuel.”
Today, when approached by suppliers of claimed fuel-saving devices, Drinkard always insists that they have an SAE/TMC test done. “But they almost never do,” he says. “They either don’t want to spend the money” – testing is not cheap – “or they’re afraid of the results. They’re gone after a year.”
“I don’t have the time or resources to test every product that comes along,” says Jerry Thrift, group manager of maintenance services for Ryder Transportation Services, Miami. “I tell suppliers, ‘If a product is so great, get behind it, commit to spending the money on an SAE/TMC test, and bring us the results.’ They go away and never come back.”
In some cases, others have done the homework for you. For example, aerodynamic aids are proven to help trucks slip through the air with less resistance. A full-roof fairing, says TMC, can produce a 15 percent improvement over nothing, while an air dam front bumper is good for 3 percent, and side skirts can boost mpg by 3 percent.
Ask tough questions
To further help fleet operators avoid being scammed, TMC has also developed a list of questions to be asked about claimed mpg-improving products, such as:
- How long has it been on the market?
- Where can it be purchased?
- What is the cost (initial, installation and cost per mile)?
- What, and over what period of time, is the return on investment?
- Have any current users been successful? Can I contact three users?
- Are there any other test results (other than SAE/TMC fuel economy)?
- Does the product affect emissions?
- What is the product’s useful service life?
- What maintenance is required?
- What warranty is offered?
- Will the product affect the life or warranty of the vehicle or components?
- Are there any handling considerations regarding installation, operation or disposal of the product?
If the supplier can’t answer the questions, or if you don’t like the answers, the decision not to buy gets easier to make.
Additives
Many products claimed to improve fuel economy are oil or fuel additives. In addition to the previous precautionary steps, the wary fleet operator will obtain assurance that such a product will not degrade critical oil or fuel properties, such as viscosity and ash content (oil), or cetane rating, vapor pressure, stability, cloud point, pour point and flash point (fuel). Specifically for fuel additives, see TMC RP 312, “Qualifying questions to minimize the potential for negative side effects from an aftermarket diesel fuel additive package.”
Tried and true
In some instances, it’s relatively safe to rely on information gathered by others. For example, TMC has found that:
- An on/off cooling fan, compared to a viscous fan, can yield a 1.5 to 5 percent fuel economy improvement;
- A 12 to 13 CFM air compressor, as opposed to a 15 to 17 CFM unit, can improve mpg by up to .5 percent;
- A 25-inch tractor-trailer gap, versus a 35-inch gap, can produce a 0.5 to 1 percent improvement;
- A standard roof deflector, as opposed to nothing, can boost mpg by up to 6 percent, while a full-roof fairing can produce a 15 percent improvement over nothing;
- An air dam front bumper is good for up to 3 percent;
- Side skirts can also boost mpg by 3 percent;
- A smooth-side trailer can yield a 2 to 4 percent improvement over an exterior-post design;
- Rib drive tires, as opposed to lug, can give a 2 to 4 percent improvement;
- Synthetic transmission/axle lube can boost mpg by up to .5 percent in summer, and up to 2 percent in winter.
These findings are based on Class 8 tractors coupled to 48- to 53-foot trailers, with maximum GCWs of 80,000 pounds, at speeds of 65 to 70 mph.
In evaluating more exotic products, as well as checking one brand against another, a properly performed SAE/TMC test will always tell the truth.
Just remember to take the right precautions, ask the right questions – and don’t get taken for a ride.
Testing while earning money
While SAE/TMC Type II and III fuel economy tests use portable fuel tanks (weighed before and after the test) and/or fuel flow meters, the Type IV test uses standard, over-the-road equipment and existing fuel tanks. This makes the Type IV well suited to testing while hauling freight.
In a Type IV fuel economy test, two tractor-trailer combinations are dispatched together. During a one hour warm-up period, the drivers practice speed management using visual and voice contact. Both tractors and trailers are identical except for the component being tested.
Gross vehicle weights must be within 5 percent, and both trucks have their left-side tank isolated, and their right-side tank drained. The right-side tank will be filled from the same pump, to assure equal heat content.
At the end of the warm-up period, both trucks pull into a truck stop and top-off their tanks, one at a time, from the same spot at the same pump. The fuel is brought up to a predetermined point in each tank very carefully, and the temperature is taken with a remote-reading, digital thermometer from a point near the center of the tank. Care is taken to assure that engine-on time and distances moved within the truck stop are equal.
Both drivers leave the fuel station together. The lead driver establishes and maintains the test speed while the following driver establishes and maintains a 15 to 45 second gap between the two vehicles.
Neutralizing drivers
Within 5 percent of the test run midpoint, the drivers pull into a facility that will permit dropping the trailers. The drivers swap tractors but stay with the trailers they pulled during the first half of the run. This eliminates any effect that drivers or trailers might have on the test results.
After leaving the midpoint equipment-switch facility, the driver who led the first half of the test run must lead during the second half. The following driver must maintain the same gap used during the first half.
At the end of the test run, the trucks are again fueled, one at a time, from the same spot at the same pump. The fuel is very carefully brought up to the same, predetermined point on the filler neck (or to the same point on a free-swinging dipstick scale).
After filling each tank, the gallons and tenths of gallons added are recorded, the fuel tank temperature is recorded and a correction to 60 degrees F is calculated. Temperature correction is necessary because fuel density, or energy content of a given volume of fuel, changes with temperature.
Three times does it
The trucks have now completed one test run and are free to complete their trip. Three tests must be completed, and the results must fall within 2 percent of each other for the entire sequence to be valid.
While some fleet managers may opt to perform a Type II, III or IV test on their own, there are independent labs and consultants who can help them. Fleet operators supplying their own equipment should expect to pay $6,000 to $8,000 depending on the consultant’s level of involvement plus expenses (travel, lodging, etc.). Two well respected testers are the Southwest Research Institute, San Antonio, (210) 684-5111 or www.swri.org; and Claude Travis and Associates, Grand Rapids, Mich., (616) 364-0869.
To order a copy of RP 1109, RP 1102 (Type 2) or RP 11103 (Type III), call TMC at (703) 838-1763 or visit this site.
On guard!
The Federal Trade Commission warns consumers to be wary of devices claimed to improve fuel economy. Quantifying such improvements can be tricky, FTC notes, because fuel economy is influenced by many variables, including temperature, traffic, road and weather conditions, driving habits and vehicle and engine condition.
The Environmental Protection Agency has evaluated “more than 100” devices claimed to save fuel, and reports that, for the few devices that provide any measurable benefit, the gains are very small.
Products found to provide no benefit include: intake air modifiers, claimed to increase turbulence and promote better combustion; fuel-line magnetic devices, claimed to improve the molecular structure of fuel before combustion; and oil and fuel additives. The FTC has charged several suppliers of these products with making misleading and unsubstantiated claims.
It should be noted, however, that EPA testing is done on a laboratory dynamometer. CCJ has uncovered no SAE/TMC test results on these products.
For more information on FTC and EPA findings and warnings, visit this site.
