ABSTRACTGlobal fuel economy and CO2 reduction mandates aredriving the need for a substantial increase in vehicle fuelefficiency over the next several years, with improvementscoming from many sources. This paper describes a vehicledemonstration program to improve fuel economy byimplementing a systems approach to reduce friction andparasitic losses. The work concentrated on nearer termtechnologies that can be quickly transferred to productionvehicle programs. Major technologies demonstrated on thevehicle included gasoline direct injection (GDi) with cooledEGR, advanced valvetrain, rollerization of both crankshaftand camshaft, and stop-start engine operation.

The work described in this paper comprises Phase I of a twophase program funded by DOE contract DE-EE0003258. Itincludes a hardware overview and a description of the systemdevelopment activities. Results focus on vehicle fueleconomy benefits compared to a production baseline vehicle.

INTRODUCTIONRegulatory trends are placing increased pressure on fuelconsumption throughout the world. As an example, Figure 1shows the rollout of fuel consumption targets for the U.S.,Europe, and China over the next several years. Dramatic fuelconsumption / CO2 reductions are necessary, both near-termand long-term, in order to meet legislative requirements. Thisis driving the need for substantial innovation to develop andbroadly deploy technologies on vehicles that provide the

required efficiency improvements while also meetingcustomer expectations for performance, comfort and safety.

Figure 1. Rollout of light duty fuel consumption / CO2targets.

A range of options are available to reduce vehicle fuelconsumption ([1] offers one recent assessment of a number ofavailable options). At the vehicle level, reduction in vehiclemass, aerodynamic drag, and tire rolling resistance decreasethe net energy required for propulsion. Other technologiesconcentrate on increasing the overall efficiency of the fuelconsumed to provide the useful work required to propel thevehicle. These include engine and transmission technologiesto improve the efficiency of the combustion process, as wellas methods to reduce parasitic losses due to friction, pumpinglosses, engine accessory loads, and engine idling. Vehicleelectrification is one means to significantly reduce vehiclefuel consumption. However, electrification currently carries a

Development and Vehicle Demonstration of aSystems-Level Approach to Fuel EconomyImprovement Technologies

2013-01-0280Published

04/08/2013

Keith A. Confer and John KirwanDelphi Powertrain

Nayan EngineerHyundai-Kia America Technical Center Inc

Copyright © 2013 SAE International

doi:10.4271/2013-01-0280

marked increase in vehicle cost. While the fraction ofelectrified vehicles, especially hybrid electric vehicles(HEVs), is expected to grow in the coming years, internalcombustion engines are projected to continue being adominant propulsion source for a number of years into thefuture (see Figure 2). Thus, technologies focused onimproving the efficiency of these engines have broadapplicability.

Figure 2. Projected global market penetration for majorpowertrain architectures. Forecast developed using

market share data from IHS.

Delphi Automotive Systems, LLC and Hyundai AmericaTechnical Center Incorporated (HATCI) are currentlyworking together in a program partially funded by the U.S.Department of Energy to develop and demonstrate gasolineengine technologies offering substantial fuel economyimprovements. A significant gain in fuel economy isexpected to come from development and demonstration of alow temperature combustion scheme called gasoline directcompression ignition (GDCI) under development in Phase IIof the program. GDCI combustion is showing excellentresults to date. Progress in developing GDCI is documentedin a number of publications [2,3,4,5], and is not consideredfurther in this paper.

The subject of the present paper is to document the Phase Istudy for this program, which has recently been completed.Phase I focused on the fuel economy impact of nearer termtechnologies that could be quickly deployed on productionvehicles. Two development vehicles were ultimately used toevaluate technology combinations providing more efficientcombustion and reduced parasitic losses. The sections thatfollow offer a description of the technologies implemented onthe two vehicles and their observed benefits to vehicle-levelfuel economy.

FUEL ECONOMY IMPROVEMENTTECHNOLOGIESTable 1 indicates the fuel economy technologies evaluated inthis study. The focus of our work was near-term applicationrather than longer term development. Thus, all technologiesevaluated are readily available. As shown in the table, thetechnologies covered a variety of mechanisms to improvevehicle fuel economy, from improving combustionthermodynamics to reducing parasitic losses due to enginefriction, accessory loads, pumping and engine idling.

Table 1. Fuel economy technologies evaluated

The two development vehicles used in this study were bothderived from a production 2011 Hyundai Sonata with a 2.4LTheta II engine and a six speed manual transmission. Bothvehicles implemented gasoline direct injection (GDi). Figure3 shows the major components for GDi fuel systemscomprising inwardly-opening, multi-hole GDi injectors, afuel rail and an engine-driven high pressure fuel pump. GDiis a well-established technology to enable improved vehiclefuel economy, and its worldwide market share is projected tomarkedly increase as indicated in Figure 2. In many cases,GDi is combined with turbocharging and engine downsizingto improve vehicle fuel economy (see, for example, [6] forone analysis of the benefits of GDi in downsized,turbocharged engines). Neither vehicle in the present studywas turbocharged. However GDi is also a fuel economyenabler in naturally aspirated engines as described, forexample, in [7,8,9]. GDi benefits in naturally aspiratedengines result largely because it allows increasedcompression ratio, and because it complements othertechnologies such as variable valve actuation

Figure 3. Gasoline Direct Injection (GDi) systemhardware

Both vehicles also applied cooled exhaust gas recirculation(CEGR). The CEGR system consisted of an exhaust gasrecirculation valve, an air to liquid heat exchanger and lowvolume plumbing to route the exhaust gas (see Figure 4). TheEGR charge was introduced ahead of the intake throttle bodyin such a way as to promote even distribution for exhaust gasto each cylinder. Cooled EGR provides charge dilution andlower in-cylinder heat transfer for reduced pumping lossesand improved combustion thermodynamics.

Figure 4. Cooled Exhaust Gas Recirculation (CEGR)system.

The remaining technologies were split between the twodemonstration vehicles. Broadly, Vehicle 1 focused ontechnologies to reduce engine friction and accessory loads.Vehicle 2 focused on pumping losses and engine idlingreduction. A brief description of the technologies on eachvehicle is offered below.

Vehicle 1Vehicle 1 implemented technologies that did not require anymajor changes to the engine control module or engine controlalgorithms and only minor changes to the vehicle's

production calibration. Engine friction reduction wasaddressed on Vehicle 1 through piston group frictionreduction, camshaft and crankshaft bearing rollerization,exhaust heat recovery, and engine downspeeding. Accessoryload reduction was accomplished with a two-step variabledisplacement oil pump.

Piston group friction reduction comprised reduced springload and low friction coatings (see Figure 5). Previous workhas shown that the oil control ring has a substantial impact onthe friction of the total ring pack [10]. Oil ring friction wasreduced in the present study by reducing the radial springload applied by the oil control ring onto the cylinder bore.The ability to reduce the oil ring spring load was partiallyenabled by engine downspeeding (described in a followingsection). Optimization work was done to ensure that the oilring maintained sufficient radial force to cope with boredistortion and thermal expansion such that oil consumptionwas not adversely affected over the engine's operating range.

Figure 5. Piston Group hardware

Further piston group friction reduction derived from coatingsto the top compression ring and the piston skirt. ChromiumNitride (CrN) coatings were applied to the compression ringusing physical vapor deposition (PVD). These coatings havebeen reported to have the lowest friction coefficients amongcurrently-available wear resistant ring coatings [11].Additionally, solid lubricant Molybdenum Disuphide (MoS2)coated piston skirts were used. Previous studies suggest thatthe piston itself contributes up to 30% of the total pistongroup friction [12] and that MoS2 offers similar frictionreduction as provided by forced lubrication at the piston skirtthrust face to bore interface [13].

Additional engine friction reduction efforts in this studyfocused on the crankshaft and camshaft. Some reduction wasaccomplished by implementing a roller-type timing chainwith reduced tension. More significantly, stockhydrodynamic support bearings were replaced with needleroller bearings (NRBs) as shown in Figure 6. The split cageNRBs were used with purpose built crankshaft andconnecting rod assemblies. Similarly, the camshaft supportbearings were modified to NRBs for the direct actingvalvetrain. Here each camshaft had 4 bearings converted toNRBs. Only the front #1 location near the cam phaser support

retained a journal bearing. This was required to help maintainpressurized lube supply to the hydraulic cam phasers locatednear this bearing.

Figure 6. Roller bearing application to camshaft andcrankshaft

In addition to offering lower bearing friction, the NRBs alsoenabled lower engine oil flow rates to the main bearings,connecting rod big ends and camshaft bearing locations.Results from previous studies indicate the potential forsignificant potential benefits due to both bearing frictionreduction and reduced oil pump demand [14]. Reduced oilflow to meet the lower demand in the present study wasaccomplished by using a 2-step variable displacement oilpump. A schematic for this newly-developed pump is shownin Figure 7. Active oil pressure control via an electricsolenoid switched the pump between low and high modebased on engine speed and load.

Figure 7. Two Step variable displacement oil pump

Exhaust heat recovery was another technology employed forfriction reduction. The exhaust heat recovery system (EHRS)employed a heat exchanger in the exhaust downstream of thecatalytic converter to provide captured waste exhaust heat tothe engine lubricating oil. Additional heating of thelubricating oil reduces its viscosity thereby helping to reduceengine internal friction. Lubricating oil viscosity reduction isparticularly effective during cold start-up when engineinternal friction is high. Figure 8 shows a schematic diagramof the switchable EHRS used to manage heat flow to thelubricating oil circuit. As a complement to the EHRS, waterjacket inserts were used in the coolant flow passages topreferentially channel coolant to the top of the cylinder bore

where cooling demands are greatest. Preferential coolingfurther optimizes oil viscosity to reduce engine friction [15].

Figure 8. Exhaust Heat Recovery System (EHRS)

Engine downspeeding is the final major fuel economyimprovement technology applied to Vehicle 1.Downspeeding was achieved by modifying the transmissionratio. Compared to the baseline engine, rated speed wasreduced from 6300 RPM down to 5000 RPM. Downspeedingprovided reduced friction both directly via reduced enginespeed, as well as by enabling reduced oil ring spring load asdescribed earlier. By increasing engine operating load at agiven power requirement, engine downspeeding also reducedpumping losses and improved engine thermodynamicsafforded at higher engine loads. Engine downspeeding isoften accompanied by engine boosting; however the engineremained naturally aspirated in this evaluation study. Toaugment the down speeded engine's performance, a tallerfinal gear ratio set was added to give a 6 % lower N/V in 1st,2nd and 4th gear and 9% lower N/V in 3rd, 5th and 6th gearscompared with the baseline ratios. Reducing the rated speedof this engine resulted in a reduction in engine power so thatits final value was approximately the same as the PFI baselinevehicle. Consequently the fuel economy difference due todownspeeding reflects an improvement for an engine withsimilar performance.

Vehicle 2Fuel economy technologies on Vehicle 2 did require changesto the engine control system. For this vehicle, a new enginecontrol module was selected for the application and projectspecific algorithms were developed where required. Fullpowertrain calibration was completed using an enginedynamometer engine and the demonstration vehicle.

Vehicle 2 addressed pumping losses via 2-step variable valvelift (see Figure 9) and electric cam phaser (see Figure 10). A

variable valve lift system with cam phasing allowed separateconsideration of differing engine operating conditions.Higher loads utilized high valve lift with phasing optimizedfor good engine torque. Lower loads implemented reducedvalve lift and duration to reduce the air mass delivered to thecylinder at a given manifold pressure for reduced pumpinglosses. The low load scheme implemented in this engine alsoapplied asymmetric lift between the two intake valves forincreased charge motion to help combustion. Compared to ahydraulic cam phaser, an electric phaser (ePhaser) offersincreased phasing rate and higher precision. An ePhaser alsooffers the ability to change cam phasing at zero engine speedand at high and low temperature extremes where oil viscosityeffects make phasing difficult with hydraulic phasers.

Figure 9. 2-step variable valve lift mechanism

Figure 10. Electric Cam Phasers (ePhasers) as used onboth intake and exhaust cams

Stop-start addressed engine idling losses in Vehicle 2 byshutting the engine off when the vehicle was stopped, andthen restarting the engine immediately before vehicle drive-away. Stop-start was mechanized in two ways during thestudy. The control system developed using rapid prototypingwas capable of controlling either mechanization. The firstmechanization simply comprised using the existing 12Vgeared starter motor to restart the vehicle. A secondmechanization consisted of adding a 14V belt-alternator-starter (BAS) system mounted to the front accessory drive, asshown schematically in Figure 11. This 14V BAS unit had a

maximum torque capability of 40 N-m. Fourteen volt systemsare typically designed for a maximum engine displacement of1.6L; however this unit was recently applied successfully to a2.4L engine [16]. It was selected in the present study becauseit offered an easily packaged mechanization of a BAS systemfor evaluation purposes. The BAS system was used for re-start purposes only and did not add tractive force to thevehicle.

Figure 11. Belt Alternator Starter(BAS) system

EXPERIMENTAL RESULTS /DISCUSSIONVehicle fuel economy and emissions tests were performed atHATCI's emissions site in Superior Township, Michigan. TheEPA Federal Test Procedure (FTP) and Highway FuelEconomy Test (HWFET) drive cycles were used for all of thefuel economy testing and combined, unadjusted values werecalculated from the test cycle results. All test methods, fuels,vehicle settings and procedures were consistent for Vehicle 1,Vehicle 2 and a baseline PFI vehicle. Both Vehicle 1 andVehicle 2 met the same tailpipe emissions standards as theoriginal production vehicle from which they were derived.

Table 2 below highlights key differences between the 2009baseline PFI vehicle and the 2011 GDi Sonata vehicles.Higher compression ratio afforded by gasoline directinjection, electric driven power steering, improved Cd withlower friction in the driveline and reduced curb weight aresome inherent advantages the 2011 Sonata has over thebaseline vehicle prior to deploying fuel economyimprovement technologies described above.

Table 2. Vehicle comparison

The overall fuel economy test results for Vehicle 1 are shownin Figure 12. Fuel economy improvements of 13.9% wereachieved for the highway drive cycle compared to the PFIbaseline vehicle. City fuel economy was improved by 12.6%and a combined unadjusted fuel economy improvement of13.1% was realized for the vehicle.

Figure 12. Fuel Economy test results for Vehicle 1

The overall fuel economy results for Vehicle 2 are shown inFigure 13. A fuel economy improvement of 13.4% wasachieved for city drive cycle compared to the PFI baselinevehicle. Highway fuel economy was improved by 12.8% andthe combined unadjusted fuel economy improvement was13.4%.

Figure 13. Fuel Economy results for Vehicle 2

Both vehicles showed broad benefits from the technologies.In both cases the combined fuel economy benefit was inexcess of 13% compared to the PFI vehicle. Improvementswere similar for the highway and city test cycles. Results forVehicle 1 were biased slightly in favor on the highway cyclewhile Vehicle 2 was slightly better over the city cycle.

Figures 14 and 15 give an estimated breakdown bytechnology for the overall Vehicle 1 and Vehicle 2 test resultsrespectively. For a given vehicle, exact partitioning bytechnology of the total fuel economy improvement is notpossible due to system level interactions between theindividual technologies. For example GDi was implementedwith several other changes between vehicle model yearstherefore the fuel economy improvement due to GDi iscombined with the other vehicle level changes. The estimatedcontributions represented in these figures have beendetermined through measurements of incremental fueleconomy improvements as the technologies were sequentiallyadded.

GDi plus vehicle model year upgrades were common to bothvehicles. However their fuel economy impact varied betweenVehicle 1 and Vehicle 2. As described earlier, EMS changeswere required on Vehicle 2 to implement the additionaltechnologies. The increased fuel economy, while notexpected, could be due to these changes in the engine controlsystem.

Considering Vehicle 1, base engine technologies -downspeeding and engine friction reduction - were appliedsimultaneously to the engine so that determination of theirindividual contributions is not possible. These base enginetechnologies combined, however, accounted for about onethird of the total fuel economy improvement.

Figure 14. Estimated Fuel Economy contributions bytechnology for Vehicle 1

Reduction of the accessory load through the use of a two-stepoil pump also contributed significantly to the vehicle levelimprovements. The production oil pump was constrained toover lubricating the engine in most regions in order to meetthe engine's oil demand at the high engine speed upperboundary. The two-step oil pump provided lower oilpressures and flow rates under lower engine loads to reduceparasitic losses. Optimization of the two step oil pumpallowed a balance between minimizing parasitic oil pumpingwork while supplying enough oil to minimize friction atinterfaces.

While crank-train rollerization did result in FE improvementstesting within the test cycles, further testing revealed that thebenefit did not extend into higher RPM areas that are withinnormal driving ranges. Additionally, durability concerns forcrank-train rollerization were found with the system asmechanized for this project. The rollerized camshaft systemdid not exhibit bearing problems during this study howeverengine durability testing was outside the scope of this project.

The final two technologies applied to Vehicle 1 were CEGRand EHRS. Cooled EGR applied to Vehicle 1 was found togive significant NOx reductions. This enabled slightly leanertransient engine calibration resulting in fuel economy gainswhile still meeting emissions targets. The exhaust heatrecovery system used to pre-heat the engine oil yielded littlefuel economy benefits as mechanized in this study.

Estimated fuel economy contributions for each of the fueleconomy systems incorporated in Vehicle 2 are shown inFigure 15.

The advanced valvetrain technologies (2-step valve lift andePhasers) yielded the highest fuel economy improvementgain for Vehicle 2. During the vehicle calibration, the low liftvalve operation range was maximized to take advantage ofthe reduced engine pumping work and improved fuelconsumption.

Figure 15. Estimated Fuel Economy contributions bytechnology for Vehicle 2

Considering Vehicle 2, cooled EGR again resulted in notablecombined fuel economy benefits. For this vehicle, cooledEGR was verified to have the positive effect of reducingknock due to the relatively low temperature of the inertcooled EGR gas when compared to internal EGR deliveredvia cam phasing. This knock reduction allowed use of the lowlift cam to be extended to higher loads that were previouslyknock-limited without cooled EGR. Recent work in theliterature implementing cooled EGR has generally focused onturbocharged GDi engines [17-18]. Results from the presentstudy indicate its utility for naturally aspirated engines aswell.

The Stop/Start system contributed significantly during thecity drive cycle but was not a factor in the highway portion ofthe drive schedule since there are no idle conditions duringthat test. As discussed earlier both a 14V BAS system and thestarter motor were mechanized for the stop-start function.Testing generally indicated better NVH performance for theBAS system, with no determinable difference in fueleconomy performance between the two mechanizations.However, addition of the 2-step variable valve lift system tothe vehicle resulted in an increase in motoring cylinderpressure such that the 14V BAS system did not havesufficient torque capacity for reliable re-start. Consequently,all Vehicle 2 results shown in this paper were obtained usingthe geared starter motor for stop-start.

It is interesting to discuss results from the present study incomparison with a recent report from the National Academyof Sciences (NAS) [1] that assessed fuel economytechnologies for light duty vehicles. Technologies comprisingGDi and vehicle model year upgrades in the present studywould expect to yield approximately 9% fuel economybenefit based on summation of the average values tabulatedin the NAS report. This simple summation offers a roughvalue for comparison with results from the present work. ForVehicle 1, GDi and vehicle model year upgrades yieldedabout a 2% improvement in fuel economy compared to thePFI baseline vehicle. The larger 4% improvement offered byGDi and model year upgrades for Vehicle 2 was alsonoticeably lower than the 9% rough target from the NASreport. Fuel economy benefits will vary vehicle-by-vehicle,

and interactions between technologies affect their impact onfuel economy.

Additionally the model year upgrades included increasedengine power and torque (see Table 2). These factors likelycontribute to the reduced fuel economy benefits in this studycompared to the rough target from the NAS report.

Engine downspeeding and friction reduction combined tooffer approximately 4.5% fuel economy benefit in the presentstudy. The NAS report attributed an average 1.3% to frictionreduction, but did not directly consider downspeeding.However, the report did attribute significant fuel economybenefits to increasing the number of transmission speeds. Forexample, an average 4% fuel economy improvement isestimated for a 6-speed transmission compared to a 4-speedtransmission. Engine downspeeding is one factor that resultsin improved fuel economy for vehicles with a greater numberof transmission speeds. Using the NAS report as a guideline,the measured fuel economy benefits for downspeeding andfriction reduction are within a reasonably expected range forthis technology combination.

Rollerization was not considered in the NAS report.However, the benefits of this additional friction reductiontechnology in the present study are estimated to be roughlythe same as the total average benefit for friction reduction inthe NAS report. Nevertheless, based on durability concernsand increased friction at rollerization does not appearattractive at this time for a production vehicle application.

Neither cooled EGR nor exhaust heat recovery wereconsidered in the NAS report, so a direct comparison withresults for these technologies in the present study is notpossible. However, the EHRS was implemented to reducefriction by heating the engine oil to provide more favorableviscosity. The NAS report did consider low frictionlubricants, whose estimated fuel economy benefits were only0.5%. In this light, the marginal benefit attributed to exhaustheat recovery in the present study is not surprising.

The last technology groups for comparison with the NASreport are stop-start, the two-step oil pump, and advancedvalvetrain (2-step valve lift with ePhaser). Stop-startaccording to the NAS report (described therein as 12V BASMicro-Hybrid) offers an estimated 3% fuel economy benefit,while in the present study stop-start contributed an estimated2% benefit. The two-step oil pump comprises an improvedaccessory. The NAS report attributes an average 1% fueleconomy benefit collectively to improved accessories. This issignificantly lower than the approximate 3% benefitestimated for the 2-step oil pump in the present study.Finally, the NAS report estimates a 2.3% benefit for discretevariable valve lift. However, other studies focused on 2-stepVVL indicate fuel economy gains of roughly 5% (see, for

example, [19-20]. The present work estimates about a 5.5%benefit for 2-step combined with eVCP.

SUMMARY AND CONCLUSIONSThis study considered a number of readily availabletechnologies for spark-ignition engines to improve vehiclefuel economy in the short term through improvedthermodynamics, reduced friction, improved accessories andlower pumping losses. The technologies were evaluated usingtwo demonstration vehicles. Fuel economy was determinedover the EPA FTP and HWFET drive cycles

These demonstration vehicles were derived from a production2011 Hyundai Sonata. Each demonstration vehicle met UStailpipe emissions standards. Using a systems level approach,different technologies were evaluated on the two vehicles,although GDi and cooled EGR were common to bothvehicles.

Each of the two vehicles demonstrated in excess of 13%improvement in EPA combined fuel economy compared to a2009 Hyundai Sonata PFI baseline vehicle. Minimal overlapbetween technologies implemented on the two vehiclessuggests that further combination of favorable technologiesevaluated in this study would likely offer furtherimprovement on a single vehicle whose fuel economyimprovement could approach 20% compared to the PFIbaseline.

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CONTACT INFORMATIONKeith ConferEngineering ManagerDelphi Advanced Powertrain3000 University DriveAuburn Hills, MI 48326keith.confer@delphi.com

John KirwanChief ScientistDelphi Powertrain3000 University DriveAuburn Hills, MI 48326john.e.kirwan@delphi.com

Nayan EngineerManager Engine Design and Test GroupHyundai-Kia America Technical Center, Inc.6800 Geddes RoadSuperior Township, MI 48198nengineer@hatci.com

ACKNOWLEDGMENTSThe authors gratefully acknowledge work contributions fromHarry Husted, Gregg Roth, Mike Lavan, Gary Fulks,Timothy Henshaw, Andrew Fedewa, Robert Hammond,Edward Joo, Donald Johnson, Jason Eiseman, JeremyKraenzlein, Jeff Cowan, Xiaojian Yang, Raymond Parker,and Paul Rau (from Delphi Automotive Systems, LLC), JohnJuriga, Sung Seo Park, Dong Suk Chae, Sangsik Kim, PaulArlauskas, Mark Bourcier, Mark Shirley, Thomas Hollowell,Steven Stewart, Jeffrey Hollowell, Joel Cherry, StevenRathbun and Eric Seaberg (from Hyundai-Kia AmericanTechnical Center, Inc.)

Research sponsored by the U.S. Department of Energy,Office of Energy Efficiency & Renewable Energy undercontract DE-EE0003258

DEFINITIONS/ABBREVIATIONSBAS - Belt alternator starterCEGR - Cooled exhaust gas recirculationCO2 - Carbon Dioxide

CrN - Chromium NitrideDOE - Department of EnergyEGR - Exhaust gas recirculationEHRS - Exhaust heat recovery systemEMS - Engine management systemEPA - Environmental Protection AgencyFE - Fuel economyFTP - Federal Test ProcedureGDCI - Gasoline direct compression ignitionGDi - Gasoline direct injectionHATCI - Hyundai America Technical Center, Inc.HEV - Hybrid electric vehicleHWFET - Highway Fuel Economy TestL - LiterMoS2 - Molybdenum Disulphide

NRB - Needle roller bearingN/V - Engine Speed [rmp]/Vehicle Speed [mph]NVH - Noise vibration and harshnessPFI - Port fuel injectionPVD - Physical vapor depositionrmp - Revolutions per minute

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