Quinney fuel loss terminology

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Analyzing and ReducingAnalyzing and Reducing

Your Fuel EconomyYour Fuel EconomyBy: Bret QuinneyBy: Bret Quinney

Vehicle DesignVehicle Design

ME 497ME 497

1212--55--0707



Fuel EconomyFuel Economy

Fuel EconomyFuel Economy--the amount of fuel it takes to move your the amount of fuel it takes to move your vehicle a certain distancevehicle a certain distance

A few reasons for bad fuel economy:A few reasons for bad fuel economy: Engine ProblemsEngine Problems

Poor aerodynamic dragPoor aerodynamic drag High rolling resistanceHigh rolling resistance

BrakingBraking

Poor operating decisionsPoor operating decisions

Only about 15%Only about 15%--20% of the fuel that you put into your 20% of the fuel that you put into your

car goes into getting your car down the road, the rest of car goes into getting your car down the road, the rest of the energy is lost.the energy is lost.

What can we do to save money,energy, and theWhat can we do to save money,energy, and theenvironment?environment?



Losses of Energy



Reducing Aerodynamic DragReducing Aerodynamic Drag

D = ½ **V^2*CD = ½ **V^2*CDD*A*A

You can improve aerodynamic drag from air You can improve aerodynamic drag from air

dams, spoilers, tonneau covers, and many other dams, spoilers, tonneau covers, and many other

car body modifications.car body modifications.

While in motion, where¶s the resistance at?While in motion, where¶s the resistance at?

air drag accounts for about 60% of total resistanceair drag accounts for about 60% of total resistance

tire rolling resistance accounts for about 25%.tire rolling resistance accounts for about 25%. The rest is accounted for friction in the driveline.The rest is accounted for friction in the driveline.



Tonneau cover Tonneau cover

For a full size truck, changing CFor a full size truck, changing CDD by .01by .01

will approximately change fuel economywill approximately change fuel economy

by .1mpg.by .1mpg. A tonneau cover covers the bed of a truckA tonneau cover covers the bed of a truck

or a convertible to reduce air drag.or a convertible to reduce air drag.

The addition of a tonneau cover will resultThe addition of a tonneau cover will result

in a drag reduction of 2 to 7% and anin a drag reduction of 2 to 7% and an

improvement of .1 to .3 mpg.improvement of .1 to .3 mpg.



Air Dams/SpoilersAir Dams/Spoilers

Air DamsAir Dams--An extension attached below the frontAn extension attached below the frontbumper, improves vehicle performance bybumper, improves vehicle performance bylimiting the airflow that is flowing over thelimiting the airflow that is flowing over the

vehicle. Air dams can assist in reducingvehicle. Air dams can assist in reducingaerodynamic lift, turbulence, and drag.aerodynamic lift, turbulence, and drag.

The increase in frontal area is compensated byThe increase in frontal area is compensated bythe decrease in drag.the decrease in drag.

Rear spoilers help decrease resistance onRear spoilers help decrease resistance onoverflow and smooth undertrays can helpoverflow and smooth undertrays can helpdecrease drag for underflow.decrease drag for underflow.



Percentage of Drag on SpecificPercentage of Drag on Specific

Sections on Car with CSections on Car with CDD

=.29=.29



Percentage of Drag on thePercentage of Drag on the

Underside of the Car with CUnderside of the Car with CDD

=.26=.26



Effects of Rolling ResistanceEffects of Rolling Resistance

RRf f + R+ Rr r = f*(W= f*(Wf f + W+ Wr r ) = f*W) = f*W

Differences in rolling resistances because tireDifferences in rolling resistances because tirematerial and geometry/traction can differ up tomaterial and geometry/traction can differ up to20 to 30% because the friction factor (f)20 to 30% because the friction factor (f)changes.changes.

An efficient car An efficient car--(Ford Focus) can save up to 6%(Ford Focus) can save up to 6%in gas by using optimal lower rolling resistantin gas by using optimal lower rolling resistanttires, going from 30 to 32mpg.tires, going from 30 to 32mpg.

Optimal tire inflation is 35psi for minimum rollingOptimal tire inflation is 35psi for minimum rollingresistanceresistance Under Under--inflated at 28 psi can decrease rollinginflated at 28 psi can decrease rolling

resistance up to 12.5%.resistance up to 12.5%.



Typical Rolling Resistant FrictionTypical Rolling Resistant Friction

FactorsFactors Low resistant tires, car/truck tires on aLow resistant tires, car/truck tires on a

smooth roadsmooth road

0.0060.006 toto 0.010.01

Ordinary car tires on concreteOrdinary car tires on concrete

0.0100.010 toto 0.0150.015

Car on stone platesCar on stone plates

0.0200.020Car/bus on teer/asphaltCar/bus on teer/asphalt

0.0300.030



Comparing Drag and RollingComparing Drag and Rolling

ResistanceResistanceEffects of Speed Between Drag and Rolling

Resistance

m m

km/h

p

ercentage of total work

drag

rolling resistance

As you can see dragAs you can see dragand rolling resistanceand rolling resistancehave different effectshave different effects

at different speeds.at different speeds. It takes more work toIt takes more work to

overcome drag atovercome drag athigher speeds.higher speeds.

Overcoming rollingOvercoming rollingresistance is harder atresistance is harder atlower speeds.lower speeds.



Other Energy Efficient AlternativeOther Energy Efficient Alternative

VehiclesVehicles Diesel enginesDiesel engines About 30About 30--35% more efficient than gasoline engines.35% more efficient than gasoline engines.

Hybrid vehiclesHybrid vehicles Regenerative brakingRegenerative braking

Electric motor drive assistElectric motor drive assist

Automatic start/shutoff Automatic start/shutoff

Electric vehiclesElectric vehicles Converts 70% of its chemical energy to power the car, compared to 20% for Converts 70% of its chemical energy to power the car, compared to 20% for

gasoline enginesgasoline engines

AFVs (Alternative Fuel Vehicles)AFVs (Alternative Fuel Vehicles)

EthanolEthanol BiodieselBiodiesel

Natural gasNatural gas

PropanePropane

HydrogenHydrogen

FCVs (Fuel Cell Vehicles)FCVs (Fuel Cell Vehicles)



New Fuel Saving TechnologiesNew Fuel Saving Technologies

TechnologyTechnology Avg. EfficiencyAvg. Efficiency

IncreaseIncreaseVariable Valve Timing and LiftVariable Valve Timing and Lift 5%5%

Cylinder DeactivationCylinder Deactivation 7.5%7.5%

Turbochargers/SuperchargersTurbochargers/Superchargers 7.5%7.5%

Integrated Starter/Generator Integrated Starter/Generator 8%8%

Direct Fuel InjectionDirect Fuel Injection 1111--13%13%

Continuously Variable Transmissions (CVTs)Continuously Variable Transmissions (CVTs) 6%6%

Automated Manual Transmissions (AMTs)Automated Manual Transmissions (AMTs) 7%7%



Is the Government Doing AnythingIs the Government Doing Anything

to Help?to Help?CAFE (Corporate Average Fuel Economy)CAFE (Corporate Average Fuel Economy)

is a government agency that requiresis a government agency that requiresmanufacturers to average their totalmanufacturers to average their total

productivity of vehicles to certain industryproductivity of vehicles to certain industryfuel consumption standards:fuel consumption standards:

27.5mpg for cars27.5mpg for cars

20.7mpg for light trucks.20.7mpg for light trucks.

Tax incentives for buying alternativeTax incentives for buying alternativeenergy vehicles.energy vehicles.



ConclusionConclusion

Reducing drag and rolling resistance canReducing drag and rolling resistance cangreatly affect fuel economy, especiallygreatly affect fuel economy, especiallyover periods of time.over periods of time.

Using new fuel saving technology willUsing new fuel saving technology willsignificantly save you money, thesignificantly save you money, theenvironment, and save energy.environment, and save energy.

The design of future technologicalThe design of future technologicaladvances is in our hands asadvances is in our hands asengineers.engineers.



Any QuestionsAny Questions



ReferencesReferences

�� Anglin, Donald L., and Crouse, William H.,Anglin, Donald L., and Crouse, William H., AutomotiveAutomotiveMechanics 9Mechanics 9thth Ed.Ed., New York, 1985., New York, 1985.

�� Riley, Robert Q.,Riley, Robert Q., Alternative Cars in the 21Alternative Cars in the 21stst Century Century, Society of , Society of Automotive Engineers, Inc., Warrendale, 1994.Automotive Engineers, Inc., Warrendale, 1994.

�� http://http://www.fordvehicles.com/help/glossary www.fordvehicles.com/help/glossary

�� http://http://www.autotrader.com/research/shared/article_id=22079www.autotrader.com/research/shared/article_id=22079

�� http://www.autospeed.drive.com.au/cm5/article.html?&A=245http://www.autospeed.drive.com.au/cm5/article.html?&A=24555

�� http://www.treehugger.com/files/2005/05/low_rolling_res.phphttp://www.treehugger.com/files/2005/05/low_rolling_res.php�� http://www.tireack.com/tires/tiretech/techpage.jsp?techid=29http://www.tireack.com/tires/tiretech/techpage.jsp?techid=29

�� http://www.fueleconomy.gov/feg/atv.shtmlhttp://www.fueleconomy.gov/feg/atv.shtml

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Quinney fuel loss terminology