Download white paper on fuel economy

March 2006
WHITE PAPER
ON FUEL ECONOMY
KENWORTH TRUCK COMPANY
WHITE PAPER ON FUEL ECONOMY KENWORTH TRUCK COMPANY
White Paper Overview
Fuel economy has always been an important consideration for truck owners – whether
you’re a fleet owner or an owner-operator. In the trucking industry, fuel is one of the
leading operating costs. Fuel economy is even more important with high diesel prices and
the coming EPA January 2007 engine emissions standards.
Kenworth Truck Company has a history of using technology to improve fuel economy.
This Kenworth White Paper on Fuel Economy will examine Kenworth’s wide-ranging
activities and offer information designed to assist truckers and fleets regarding this
important topic. Each year, Kenworth invests significant resources and conducts
extensive road and other testing in pursuit of advances in this area. Kenworth engineers
and dealers also work closely with customers on a continuing basis to strive for enhanced
fuel economy.
There are six major areas covered in this Kenworth white paper:
• Aerodynamics
• Component Spec’ing — Tire Tips (Courtesy of Bridgestone)
• Advanced Technology
• Route Management
• Driver Behavior
• Proper Maintenance
In addition, Kenworth’s website (www.kenworth.com) will provide continuing information
on this topic.
Target Miles Per Gallon & Approximate Yearly Savings ($ / %)
Current
MPG
5.5 mpg
6
6.5
7
7.5
8.0
5
$5,455
$10,000
$13,846
$17,143
(9.1%)
(16.7%)
(23.1%)
(27.2%)
5.5
——
$4,545
$8,392
$11,688
(8.4%)
(15.4%)
(21.4%)
6
——
——
$3,845,
$7,143
(7.7%)
(14.3%)
$20,000
(33%)
$22,500
(37.5%)
$14,545
(26.7%)
$17,045
(31.2%)
$10,000
(20%)
$12,500
(25%)
6.5
——
——
——
$6,154
(13.3%)
$8,654
(18.8%)
$2,857
(6.7%)
$5,357
(12.5%)
$3,297
(7.2%)
7
——
——
——
——
7.5
——
——
——
——
——
SUMMARY
5.0 miles per gallon/100,000 miles = 20,000 gallons x $3.00/gallon = $60,000
5.5 miles per gallon/100,000 miles = 18,181 gallons x $3.00/gallon = $54,543
6.0 miles per gallon/100,000 miles = 16,666 gallons x $3.00/gallon = $49,998
6.5 miles per gallon/100,000 miles = 15,385 gallons x $3.00/gallon = $46,155
7.0 miles per gallon/100,000 miles = 14,285 gallons x $3.00/gallon = $42,855
7.5 miles per gallon/100,000 miles = 13,333 gallons x $3.00/gallon = $39,999
8.0 miles per gallon/100,000 miles = 12,500 gallons x $3.00/gallon = $37,500
$2,500
(6.3%)
Fuel Economy:
A Matter of Dollars
and Sense
Calculate your own
potential fuel savings
by finding your current mpg on the left.
The column to the right
shows your approximate dollar savings per
year as you improve
your fuel economy.
Numbers are based on
driving 100,000 miles
per year and purchasing fuel at an average
of $3.00 per gallon.
1
Aerodynamics
Approximately half the energy used by a truck traveling 55 mph is to simply move the
air around that truck. At 65 mph, about two-thirds of the energy is used to cut through the air.
Kenworth can truly be called the industry’s leader
in the use of aerodynamics in truck design. After
all, it was Kenworth that brought aerodynamics
to the forefront with the 1985 introduction of the
industry’s first truly aerodynamic Class 8 truck
– the Kenworth T600A.
Kenworth engineers possessed the vision
and leadership to take the concept of using
aerodynamics in truck design to produce fuel
savings and made it reality. The result has been
billions of dollars in fuel savings for the trucking
industry since the mid-1980s.
Any discussion of Kenworth and aerodynamics would not be complete without mentioning the
late Larry Orr, the trucking industry’s “Father of Aerodynamics”. Orr was a trucking industry
visionary and innovator.
Aerodynamic Developments in the
Trucking Industry
Mid-1970s
• Airshield (Patented Vari-Shield)
Late 1970s through Early 1980s
• Rounded Corners on COEs
• Trailer Bubble Nose
• Cab Extenders
• Roof Fairings
Orr was best known for his leadership role
in the development of T600A. In recognition
of their pioneering achievement, Orr and
his Kenworth engineering and design
team received the U.S. Department of
Transportation’s National Award for the
Advancement of Motor Vehicle Research and
Development in 1995.
Kenworth’s heritage of the aerodynamic truck
continues with the aerodynamic Kenworth
T2000, which builds upon the lessons
learned from the T600A.
1985
• First Industry-Wide Aerodynamic Truck – the Kenworth T600A – with Aerodynamic Hood, Bumper and Partial Chassis Side Fairings
How do Kenworth engineers pursue even
greater fuel efficiency? They use a five-pronged
attack consisting of:
Late 1980s and Beyond
• Full Chassis Side Fairings
• Aerodynamic Mirrors
• Curved Windshield
• PACCAR Technical Center testing
• Computational Fluid Dynamics (CFD)
• Wind tunnel testing
• Real-world highway testing
• Kenworth Research & Development
Center testing
WHITE PAPER ON FUEL ECONOMY KENWORTH TRUCK COMPANY
Computational Fluid Dynamics (CFD)
Kenworth uses sophisticated computer
technology to offer aerodynamics
and fuel economy improvements. The
technology – called computational fluid
dynamics (CFD) – allows Kenworth
engineers to conduct “virtual”
aerodynamic testing.
With CFD, Kenworth engineers
simulate wind tunnel conditions on the
computer screen. This tool enables
Kenworth to evaluate different hoods,
cab-sleeper configurations and roof
fairing designs.
The integration of CFD in aerodynamics helps Kenworth
evaluate and optimize basic truck shape. CFD results
are then used to guide wind tunnel tests that are more
representative of the final design.
In addition to the study of external aerodynamics, CFD is
used to study the underhood heat transfer of the fan and
radiator and the internal flow of the Heater/Ventilation/Air
Conditioning (HVAC) system.
Wind Tunnel Testing
Kenworth has conducted wind tunnel testing since the mid-1970s. This database serves as
an information asset in meeting today’s challenges.
Kenworth uses wind tunnel testing of 20% scale truck models in pursuit of fuel economy
advances. Tests are conducted at the University of Washington Aerodynamics Laboratory
wind tunnel in Seattle. The overall objective is to identify opportunities to improve
aerodynamic performance of the trucks, validate Kenworth’s computational fluid
dynamics (CFD) simulation results, and evaluate the aerodynamic properties, such as
drag coefficients.
Wind tunnel test programs typically run
over a one-week period with individual
tests going five minutes or less to collect
aerodynamic drag force data. Tests that
utilize a smoke wand enable engineers
to visualize the airflow characteristics
over the vehicle. Wind tunnel testing
helps Kenworth study the aerodynamics
of various body shapes. Engineers also
examine the impact of all the attachments
and accessories – such as mirrors,
sun visors and cab extenders – on
aerodynamic performance.
3
PACCAR Technical Center
A third part of Kenworth’s testing program for fuel economy takes place at the PACCAR
Technical Center in Mount Vernon, Washington. The PACCAR Technical Center features
the latest state-of-the-art equipment for testing and product evaluation. Fuel economy
tests are regularly undertaken on the facility’s 1.6-mile, high-speed, banked oval track.
Testing methodology follows scientific
practices developed by the Society of
Automotive Engineers (SAE). Since fuel
consumption performance varies according
to the ambient conditions, the average
temperature, wind speed and barometric
pressure are recorded during the test runs.
Road tests are often preceded by a one-hour
warm-up of the vehicles.
Tests often involve a series of at least
three 50-mile runs on the oval with fuel calculations taken after each is completed to
ensure high accuracy. One complete test cycle covers at least 150 miles. The data and
results collected at the PACCAR Technical Center are used by Kenworth engineers
to help confirm Kenworth’s over-the-road fuel economy test results and to assess the
performance of new designs.
Real-World Testing
Kenworth engineers also take to the road for test runs designed to increase fuel economy
knowledge. This “real-world” testing is used to help confirm and verify results gathered
from the wind tunnel, computational fluid dynamics and PACCAR Technical Center.
Kenworth has
conducted such test
runs to study aerodynamics since the
1980s. The program
began in 1985 when
Kenworth took two
T600s approximately
2,000 miles from
Phoenix to Miami.
In 1991, Kenworth
ran “Tour America”,
taking three T600s
equipped with different engines nearly
7,500 miles. The
tour started from Seattle, traveled east to Pennsylvania, south to Jacksonville, west to Los
Angeles and then north to Seattle.
In 1994, Kenworth’s “Test of the Best” tour began in southern California and traveled
nearly 2,400 miles to Jacksonville, Fla. Four vehicles were involved – three T600s and
one T800. For the first time, Kenworth started using its own self-contained, fueling trailer
to utilize a consistent fuel supply for the tests.
The trailer carries six, 500-gallon fuel tanks. This allows Kenworth to simultaneously run
WHITE PAPER ON FUEL ECONOMY KENWORTH TRUCK COMPANY
up to five trucks – each with its own designated tank – on long-distance fuel economy tests. The sixth tank
is used as a spare.
In April 2001, Kenworth conducted over 1,000 miles of tests with a
T2000 on the 7.7-mile oval track at the Bridgestone/Firestone Proving Grounds in Fort Stockton, Texas. Another on-highway test of approximately 550 miles was conducted from Fort Stockton to Tucson.
During the summer of 2001, Kenworth began a series of 17 fuel
economy runs with several T2000s – with different engine models
– on a nearly 500-mile course from Renton, Washington to The
Dalles, Oregon and back again. These runs provide Kenworth with
data covering a total of 17,000 miles among the test trucks. In addition, Kenworth uses this real-world testing to evaluate prototype
aerodynamic enhancements to various components, such as cab
and cab roof extenders.
Whether it’s in the wind tunnel, on the computer, on the test track, or on the road
across America – Kenworth’s commitment is to continually explore ways to achieve
fuel economy advances that will benefit its customers.
5
Component Spec’ing
A truck uses energy to overcome aerodynamic, mechanical and rolling resistance.
Enhancing fuel economy can be achieved by reducing aerodynamic drag, minimizing
mechanical and rolling resistance or enhancing engine/powertrain efficiency. A vehicle’s
basic specifications and options can have a significant impact on fuel use.
Kenworth’s Applications Engineering Team works in conjunction with Kenworth dealers,
truck salespeople, and customers to spec vehicles to meet customers’ fuel economy requirements. For example, Kenworth engineers work to help customers hit the “sweet spot”
regarding the most efficient engine operation and fuel consumption curve for their specific
application. Here are some tips to consider.
To enhance aerodynamics:
•
Select a more aerodynamic model – T2000 or T600 – which can increase fuel
economy by an estimated 15% for over-the-road.
•
Select a sleeper package appropriate for the trailers you expect to pull. (For example,
a flat-top sleeper – as opposed to
an Aerodyne® sleeper – will achieve
Impact of Selected Components
(Potential Percent Fuel Economy Improvement in MPG*)
better aerodynamic performance
with a tank or flatbed trailer.)
•
Aerodynamic treatments will
further enhance the fuel economy
performance. This includes a roof
fairing for use with van trailers,
chassis fairings, cab extenders and
Kenworth aerodynamic mirrors.
(A roof fairing and cab extenders
typically may reduce aerodynamic
drag by 10% to 20%. A chassis
fairing may reduce drag by 2% to
3%.)
Full Roof Fairing (for use with van trailer)
5-10%
Cab Extenders 2-4%
Chassis Fairings
1-2%
Air Cleaners (underhood)
1-2%
Aerodynamic Mirrors
1-2%
* - gains are not cumulative
•
Remove accessory components from the air stream where possible. For example,
the use of underhood-mounted air cleaners – not cowl-mounted air cleaners – can
improve aerodynamics by 3% to 4%.
•
Wheelbase and fifth-wheel setting are important considerations. For aerodynamics,
get the trailer as close to the back of the cab/sleeper as possible. The narrower the
gap, the better the aerodynamics. For example, decreasing the trailer gap by 10
inches represents a 0.5% to 1% increase in fuel economy.
To reduce mechanical resistance:
•
Select components that are sized for the job – larger gear sets generally have lower
efficiencies; larger capacity tires have more resistance.
•
Use low-profile tires and aluminum wheels.
•
Use all-position tires on the rear, same tread as the steer-axle tires.
WHITE PAPER ON FUEL ECONOMY KENWORTH TRUCK COMPANY
•
Reduce the weight of “rotating” components such as tires and wheels.
•
Use wide base radial tires, replacing less fuel-efficient dual tire assemblies.
•
Reduce the inertial resistance of the combination by reducing the truck’s weight. (If more weight can be added in cargo, you do not reduce the inertial loads on the engine. But, you do improve the fuel consumption per pound of cargo.)
Select the right engine and gearing for the intended operation:
•
Engine power settings have unique torque, horsepower, and fuel-consumption
curves. Selecting an engine with excessive power can lead to inefficiencies.
•
Select a transmission for the gears that you’ll normally be running. Selecting a gear
set that has the truck cruise at the wrong rpm may decrease fuel economy by 10% to
15%. A 13- or 18-speed transmission is often the most likely selection. It’s also important to select a transmission and rear axle to match the engine and load requirements for the specific application. This selection should take into account the terrain
over which the vehicle will operate. The old saying “Gear fast, run slow” is really the
key to the best fuel economy.
•
Consider spec’ing an automated transmission in order to enhance fuel economy
through computer controlled shift logic.
•
If you have a route that you typically run, contact your Kenworth dealer for assistance in spec’ing the vehicle for that route. Kenworth dealers work closely with the engine suppliers to take into account a variety of speeds and grades. This allows the truck to be fine-tuned for optimum fuel economy.
BRIDGESTONE TIRE TIPS
Don’t forget the impact of tires on the vehicle and trailer.
Bridgestone has extensive information available on fuel economy. Bridgestone has
conducted fuel economy tests under strict scientific conditions for over 20 years. The tire
manufacturer uses the Bridgestone/Firestone Proving Grounds in Fort Stockton, Texas,
and Transportation Research Center, Inc. in East Liberty, Ohio, to test the effects of
speed, load, and tire-related factors on fuel efficiency. Bridgestone also collects data from
real-world testing conducted by customers using their trucks to haul freight.
Here are some tips to remember:
•
Tire rolling resistance accounts for about one-third of a truck’s fuel consumption. In other words, a 3% reduction in rolling resistance produces about a 1% gain in fuel economy.
•
Tread depth has a significant effect on tire fuel economy. As a tread wears, the fuel efficiency of the tire usually increases. The increase is fairly rapid at first, then slows
as the tire wears out.
•
Tire fuel efficiency, especially with fuel-saving tires, is cut nearly in half when speed is
increased from 55 mph to 75 mph.
•
Tire treads wear faster at higher speeds. Tests show that the removal mileage point may come 10% to 30% sooner.
•
Overinflation is neither effective nor recommended as a fuel economy improvement
method.
•
All axle positions are not equal; tires on different axles make different contributions to fuel economy.
7
•
Changing trailer tires to fuel-efficient types produces a larger effect than changing tractor tires to fuel-efficient types.
•
All tires are not alike. Some are better than others when it comes to fuel economy. Increased tire pressure generally means less rolling resistance and better mileage.
But conversely, it can mean more tire wear.
Bridgestone offers a video called, “What Drivers Can Do To Save Fuel”. The 9-minute
program examines such topics as:
•
Why saving fuel benefits drivers,
•
How to save fuel before the trip starts,
•
Why idle control is so important,
•
The advantages of progressive shifting,
•
How to use time management to save fuel, and…
•
Why excessive speed doesn’t pay.
Bridgestone also published a comprehensive, 56-page brochure entitled “Guide To Large
Truck Fuel Economy for a New Millennium”.
See your Bridgestone representative, call 1-800-847-3272, or email your request to
[email protected] to obtain the guide and video.
For more details on tires and fuel economy, go to Bridgestone’s website (www.trucktires.
com). Click on Library, then Publications and scroll down to Feature Publications. Click
on “Guide to Large Truck Fuel Economy for a New Millennium”, which offers an electronic
version of the guide.
WHITE PAPER ON FUEL ECONOMY KENWORTH TRUCK COMPANY
Advanced Technology
The use of advanced technology is a key area of focus at Kenworth to further enhance the
fuel economy of tomorrow’s truck. Kenworth engineers regularly explore a variety of technologies that can help to significantly reduce fuel consumption.
Is 10-plus miles per gallon feasible for a heavy-duty truck in the future? Perhaps. But it will
take technology advancements and initiatives to pursue and achieve such a goal. Kenworth
research and development engineers are working in a number of areas to study advanced
technologies that impact fuel economy. These include:
•
A digital fuel economy gauge to provide the driver with feedback on the instantaneous
fuel consumption.
•
Telematics to provide driver/vehicle utilization and productivity data for fleet operations.
•
Advanced tire-pressure monitoring systems to ensure that the tires are maintained at the proper inflation pressure.
•
Electronic vision systems offering the potential to reduce the size of, or eliminate the need for, external mirrors, thus providing improved aerodynamics.
•
Stricter engine emissions standards.
•
Hybrid electric systems to power accessory devices.
•
Kenworth High-Tech Trucks to validate promising technologies.
9
Kenworth’s digital fuel economy display under development will help a driver easily monitor fuel parameters such as road speed, engine speed and turbo boost. The display will
also provide easy-to-read data on instantaneous fuel consumption, trend graphs and
average trip fuel economy to help the driver achieve outstanding results.
Kenworth GPS and cellular communications, will help fleets monitor driver performance
trends in real-time. This system can also be used by fleets to monitor fuel consumption
and provide feedback for driver training. In addition, fleets may elect to use the system to
provide incentives to drivers for exceptional performance.
Advanced tire-pressure monitoring systems will keep drivers updated on the status of
pressure of all tires and ensure low rolling resistance. These systems will also provide
early warning of tire-pressure changes that can lead to premature wear or sudden tire
damage.
Kenworth’s Advanced Idle Management System provide heating, cooling and hotel power
without the need to idle the truck engine. This reduces fuel consumption in additional to
complying with state and federal regulations. Additional benefits include elimination of
engine noise and vibrations, which improves rest quality. The package includes enhanced
sleeper insulation and LED lighting and is fully compatible with short power.
Kenworth is involved in several projects involving object recognition technologies. In the
future, vision systems may replace mirrors, subject to government approval. It is estimated that eliminating the current mirrors and holders will offer a 3% to 4% reduction in
aerodynamic drag – or a 1% to 2% increase in fuel economy.
In addition to these efforts, Kenworth has been studying how the tougher EPA 2007
engine emissions standards will impact fuel economy performance. The industry will face
an increased challenge of achieving current fuel-economy performance with the reduced
emissions. Kenworth engineers are identifying opportunities to further optimize the integration of this powertrain and cooling system into the vehicle, thus mitigating the impact
to customers.
Even more stringent engine emissions standards are coming in 2010. To meet this challenge, Kenworth and Caterpillar have contracted with the Department of Energy on a
major project in conjunction with the 21st Century Truck Initiative. The 42-month research
and development program is exploring ways to significantly reduce truck fuel consumption and emissions. It involves engine parasitic energy-loss reduction (mechanical losses
from accessory devices driven by the engine) and enabling technologies for Class 7 and
8 trucks.
Major goals are to reduce:
•
Parasitic losses,
•
Idling emissions, and
•
Refrigerant gas leakage.
Finally, Kenworth showcases technologies that enhance customer productivity and profitability through High-Tech Trucks annually developed as concept vehicles and displayed
at many of the North American truck shows. These trucks highlight promising technologies which may eventually go into production and further help customers reduce fuel and
operating costs.
WHITE PAPER ON FUEL ECONOMY KENWORTH TRUCK COMPANY
Route Management
Route management is another important factor in fuel economy. In trucking, there are different ways to go from Point A to Point B. The goal is to get from Point A to Point B in the
most efficient and economical manner while also meeting delivery deadlines.
This can be easier said than done because even veteran truck drivers may sometimes
have trouble finding a delivery location. Some companies and drivers make many deliveries to new locations – especially on backhauls. Searching for a customer’s location can
add stress to driving. Out-of-route miles and lost time can result if a driver misses a turn,
impacting on-time delivery.
Of course, out-of-route miles also result in burning more fuel. It’s estimated that out-ofroute miles may account for between 3% to 10% of a driver’s total mileage each year.
Let’s assume 100,000 miles driven a year at 6 miles per gallon and an average cost of
$3.00 per gallon. Out-of-route miles of 3% – or 3,000 miles – requires 500 extra gallons of
diesel fuel. Multiply that by $2.50 per gallon and it equals $1,500 in additional fuel costs.
Out-of-route miles of 10% – or 10,000 miles – equates to 1,666 extra gallons of diesel
fuel. Multiply again by $3.00 gallon and it equals mearly $5,000 in additional fuel costs.
And these figures are just for one truck.
Kenworth believes it’s essential to help drivers and fleets find ways to reduce their
out-of-route miles and boost overall fuel economy and route efficiency, thus increasing
truck asset productivity.
Driver Behavior
While Kenworth engineers and the Kenworth dealer network can work closely with customers to spec a vehicle for fuel economy, driving techniques and habits have a major impact on
achieving what the specs set out to do.
Kenworth offers these tips for getting the most out of your equipment:
•
A fuel economy display is essential as the driver must be able to monitor and correct fuel economy performance by the minute. Once the fuel is used, it is very difficult to retrieve the loss. Examples of fuel economy displays are the Cummins RoadRelay and
Caterpillar Driver Information Display (DID).
•
Excessive speed is the largest single factor in reduced fuel mileage. Reduce speed to a reasonable level of say 60 mph and eliminate all non-essential stops. A general rule of
thumb is that every mph increase above 50 mph reduces fuel mileage by 0.1 mpg.
•
Use restraint when accelerating from stop. Short-shifting at 1,100 to 1,200 rpm in all the low-range gears keeps fuel consumption low and still moves the truck. The step to high range requires a bit more RPM and then use 1,500 rpm as maximum shift point. Lug
the engine to 1,150 rpm before downshifting. The upper end of the power curve – 1,500
to 1,800 or 2,100 rpm – has the most severe fuel burn rate – so try to avoid this.
11
•
Minimize idling. Five minutes of warm-up is generally adequate and cool-down is accomplished when pulling in for parking. To verify the negative effect of excessive idling, watch the fuel economy display.
Utilize these fuel-economy tips and you’ll be well on your way to receiving better fuel economy for your truck or fleet.
Proper Maintenance
Proper maintenance is also important in the fuel economy equation. Here are some
things to remember:
•
Make sure to maintain proper tire inflation pressure. Check tire wear.
•
Replace air & fuel filters at the proper intervals.
•
Keep all axles – drive and steer – properly aligned to minimize rolling resistance.
•
Monitor your fuel quality at the pump. Make sure that you are not getting dirty fuel that
causes the fuel injectors to clog or disrupt the spray pattern.
•
Repair any body damage. For example, that front corner of the dinged-up bumper hanging down hurts the vehicle’s aerodynamics, and thus, fuel economy.
•
Use a good synthetic or semi-synthetic oil in the engine and drive axles. Also use a good synthetic transmission fluid. Kenworth uses synthetic oil in the axles and transmissions of new trucks coming off the production line.
•
Don’t use a higher viscosity oil than actually needed for the operating conditions.
WHITE PAPER ON FUEL ECONOMY KENWORTH TRUCK COMPANY
13
To learn more about fuel economy, be sure to visit Kenworth’s website
(www.kenworth.com) for continuing information on this important topic.
ISO 9001. © Kenworth Truck Company, A Division of PACCAR.
For more information, please call or visit your local Kenworth dealer or visit us at www.kenworth.com
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