This document summarizes the process which utilized EPA's laboratory engine and chassis dynamometer test data to generate a full engine fuel consumption map for the Toyota A25A-FKS advanced Atkinson 2.5L engine from the 2018 Toyota Camry tested on Tier 3 fuel. The generated full engine map defines the complete operating boundaries of the engine which are needed for ALPHA modeling including idle, WOT, minimum torque, and maximum speed.
SUGGESTED CITATION:
2018 Toyota 2.5L A25A-FKS Engine Tier 3 Fuel - ALPHA Map Package. Version 2020-07. Ann Arbor MI: US EPA National Vehicle and Fuel Emissions Laboratory, National Center for Advanced Technology, 2020.
Engine Physical Characteristics
Set physical characteristics based on published information "New 2.5-liter Direct-injection, Inline 4-cylinder Gasoline Engine". (n.d.) Retrieved November 20, 2018, from https://newsroom.toyota.co.jp/en/powertrain/engine
engine = [];
engine.name = '2018 Toyota 2.5L A25A-FKS Engine Tier 3 Fuel';
engine.combustion_type = enum_engine_combustion_type.spark_ignition;
engine.displacement_L = 2.487;
engine.num_cylinders = 4;
engine.compression_ratio = 13;
engine.bore_mm = 87.5;
engine.stroke_mm = 103.4;
Test Data
Import EPA engine dynamameter test data from "2018 Toyota 2.5L A25A-FKS Engine Tier 3 Fuel - Test Data Package. Version 2020-07. Ann Arbor, MI: US EPA, National Vehicle and Fuel Emissions Laboratory, National Center for Advanced Technology, 2020." Some high load test data points exhibited unexpected behavior; specifically, at low speeds when increasing commanded accelerator pedal position the result was decreased engine torque despite additional fueling. The resulting low efficiency is not indicative of normal engine operation and thus, the suspect points have been excluded.
test_data = readtable2('4- 2018 Toyota 2.5L A25A-FKS Engine Tier 3 Fuel - Test Data.xlsx','Sheet','Steady State','VariableNamesLine',4,'VariableUnitsLine',5,'DataLine',6); ss_test_data.name = 'SS Test Data'; ss_test_data.speed_rpm = test_data.Speed; ss_test_data.torque_Nm = test_data.Torque; ss_test_data.fuel_gps = test_data.FuelMeterFlow; test_data = readtable2('4- 2018 Toyota 2.5L A25A-FKS Engine Tier 3 Fuel - Test Data.xlsx','Sheet','High Load Initial','VariableNamesLine',4,'VariableUnitsLine',5,'DataLine',6); hl_test_data.name = 'High Load Test Data'; keep = [1:6,9,12,15:40]; hl_test_data.speed_rpm = test_data.Speed(keep); hl_test_data.torque_Nm = test_data.Torque(keep); hl_test_data.fuel_gps = test_data.InjectorFuelFlow(keep);
Maximum Torque (WOT) Curve Data
Add published maximum torque data to supplement the Test Data described above.
wot_data.speed_rpm = [5000; 6600]; wot_data.torque_Nm = [184 * convert.ftlbs2Nm; 203 * convert.hp2kW * 1000 / (6600 * convert.rpm2radps)];
Minimum Torque (Zero Accelerator Pedal) Curve Data
Minimum torque data is included in the Test Data described above.
Fuel Properties
Load fuel properties provided in the Fuel Analysis Report identified in the Engine Test Data package referenced above.
engine.fuel = class_REVS_fuel('FTAG 26781');
disp(engine.fuel);
class_REVS_fuel with properties:
id: 'FTAG 26781'
description: 'Tier 3 Cert'
density_kgpL_15C: 0.7433
energy_density_MJpkg: 41.9540
carbon_weight_fraction: 82.9900
research_octane_number: 92
motor_octane_number: 84
alcohol_pct_vol: 9.6600
gCO2pgal: 8.5557e+05
energy_density_BTUplbm: 1.8037e+04
specific_gravity: 0.7440
Idle Speed
Set estimated idle speed using preliminary EPA chassis dynamometer test data for the 2018 Toyota Camry; EPA published report pending.
engine.idle_speed_radps = 580 * convert.rpm2radps ;
Engine Build for Simulation in ALPHA
Construct simulation input for the engine, combining all of the above inputs. Fit the fueling data onto a grid for simple interpolation and establish points that represent the maximum and minimum engine torque versus speed. Confirm the quality of fit between the input data and the resulting engine description by examining the resulting plots.
engine = REVS_build_engine(engine, {ss_test_data, hl_test_data},'WOT', wot_data,'plot_bsfc','plot_efficiency');
Idle Fuel Verification
Confirm appropriate fuel consumption near idle conditions. The following conditions represent tested operating conditions near idle with the surrogate transmission. The speeds and fuel flow agree with measurements recorded on this engine. However, in general, idle speeds and fueling depend on the drivetrain the engine is coupled to and may change depending on the application.
% Idle @ 628 RPM in neutral measured fuel rate ~0.15 g/sec
engine.interp_fuel_gps( 627 * convert.rpm2radps, 11.5);
0.1458
% Idle @ 590 RPM in gear measured fuel rate ~0.14 g/sec
engine.interp_fuel_gps( 590 * convert.rpm2radps, 15.7);
0.1501
Fuel Map Linearity
Confirm expected trends in output fuel map, specifically in regions where data is unavailable.
REVS_plot_engine_fuel_linearity(engine);
Model Calibration Options
Calibrate additional properties of the REVS engine model which can be set to match observed behaviors during the validation process.
Note: Default values are used unless properties are specified below, which are derived from the composite set of EPA testing and model validation activities.
Accelerator Pedal Map
Apply default pedal mapping for passenger cars, which will linearly increase engine power with accelerator pedal position.
engine.pedal_map_type = enum_engine_pedal_map_type.max_engine_power;
Transient Fueling Adjustments
Use the default adjustment factors during the simulation, since there is no transient fueling data available.
File Description
Generate and write the created ALPHA engine definition into a file for later simulation.
write_REVS_engine( 'engine_2018_Toyota_A25AFKS_2L5_Tier3.m', engine);
Engine Build: engine_2018_Toyota_A25AFKS_2L5_Tier3.m
% ALPHA ENGINE DEFINITION % Generated 29-Jul-2020 12:41:05 % Constructor engine = class_REVS_engine(); engine.name = '2018 Toyota 2.5L A25A-FKS Engine Tier 3 Fuel'; engine.source_filename = mfilename;engine.matrix_vintage = enum_matrix_vintage.present; % Physical Description engine.displacement_L = 2.487; engine.num_cylinders = 4; engine.combustion_type = enum_engine_combustion_type.spark_ignition; engine.compression_ratio = 13; engine.bore_mm = 87.5; engine.stroke_mm = 103.4; % Maximum Torque Curve engine.full_throttle_speed_radps = [ 0.00000000000000000 ; 84.508842381565429 ; 104.06526760511444 ; 105.06526760511444 ; 120.99844105301089 ; 139.00670110402751 ; 157.05114274611151 ; 181.15851237259469 ; 211.38998280647132 ; 265.49125312822645 ; 313.85974433895962 ; 423.00797082335708 ; 470.84970760835927 ; 523.59877559829886 ; 691.15038378975441 ; 725.70790297924214 ; 760.26542216872997 ]; engine.full_throttle_torque_Nm = [ 0.00000000000000000 ; 108.20000000000000 ; 133.43199071616763 ; 158.37904191616764 ; 180.67999999999998 ; 186.56054054054047 ; 194.83088235294122 ; 198.77272727272725 ; 212.66820512820510 ; 220.42264150943393 ; 219.29032258064515 ; 233.80952380952388 ; 236.01546391752564 ; 249.47051199999999 ; 219.02551316964789 ; 187.73615414541248 ; 0.00000000000000000 ]; % Minimum Torque Curve engine.closed_throttle_speed_radps = [ 0.00000000000000000 ; 138.85839528866885 ; 265.46457922833753 ; 373.95424553230504 ; 518.78166686279451 ; 760.26542216872997 ]; engine.closed_throttle_torque_Nm = [ -15.809481808158766 ; -22.899999999999999 ; -25.899999999999999 ; -30.600000000000001 ; -42.299999999999997 ; -54.630871003307611 ]; % Fuel Map engine.fuel_map_speed_radps = [ 0.00000000000000000 ; 40.762164680327558 ; 81.524329360655116 ; 117.50576634052098 ; 138.86333881584747 ; 156.96349128441210 ; 181.06021860244829 ; 211.23458327916586 ; 265.46934230094655 ; 313.74723459107747 ; 374.05468341626522 ; 422.28847961695163 ; 470.53860674269447 ; 518.79567960255429 ; 567.04234327756308 ; 603.42091616524067 ; 681.84316916698526 ; 760.26542216872997 ]; engine.fuel_map_torque_Nm = [ -57.362414553472995 ; -42.783707276736493 ; -28.204999999999998 ; -12.619166666666665 ; 2.9666666666666668 ; 12.718421052631580 ; 28.766666666666666 ; 40.812500000000000 ; 54.439999999999998 ; 63.635277777777773 ; 72.830555555555549 ; 88.879999999999995 ; 103.90000000000001 ; 114.67222222222222 ; 128.53333333333333 ; 135.84999999999999 ; 149.44604316546761 ; 159.71467160604487 ; 169.98330004662211 ; 180.67999999999998 ; 185.18837837837836 ; 196.89281344454776 ; 209.67081272319996 ; 225.33823245652508 ; 243.64113502826254 ; 261.94403760000000 ]; engine.fuel_map_gps = [ 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 ; 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.075518802205716051 0.14437071085240241 0.29170305316180417 0.43806559139141926 ; 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.046884204432192302 0.12530989919656543 0.22941155082336931 0.36611160309842505 0.50216791657841364 0.60197486512241094 0.81059750969056321 1.0164888141337547 ; 0.00000000000000000 0.029304605214868273 0.062149436896392851 0.086158908686558081 0.099098338268550162 0.11001226114027636 0.12477597999748215 0.14703828726280804 0.20063001724110135 0.26934558040764084 0.37989850940676856 0.49740245827835838 0.63831940785790198 0.79773875364498004 0.96653477337084615 1.0949211327614898 1.3692916387024585 1.6374428770296046 ; 0.0081591808105537910 0.078142872742130318 0.14859879294814068 0.20656995988571417 0.23556883224267816 0.25982613716701863 0.29277570361955818 0.33752045879143133 0.43274009037299571 0.54081953045121844 0.70881269081047604 0.86765963993580641 1.0456999128593962 1.2400883221750731 1.4452328280868205 1.6018850289290010 1.9367945239559008 2.2637168043973994 ; 0.014480632746139305 0.098068736487434402 0.18199605613108383 0.25471636477064324 0.29895719531752496 0.33659666850003150 0.38621054966114010 0.44898230246919935 0.57347240586832604 0.70680852870429078 0.91159483590984625 1.0964214166622372 1.2949333589190699 1.5152057340090472 1.7494184276413300 1.9253843180401253 2.2962764800061937 2.6597102415859566 ; 0.023645472029021196 0.13170164995201503 0.24122079652643955 0.33714364236879507 0.39833428481301769 0.45223068566644764 0.52490605998383810 0.61583974709460620 0.79721756363166330 0.97116254153220327 1.2377354696094995 1.4684165745399493 1.6929209793948210 1.9606347701692561 2.2552915680287131 2.4630045256302791 2.8945709494879508 3.3217512077491698 ; 0.032971118104613915 0.16177618597478324 0.28943307609323210 0.40556188376557556 0.47935201951522194 0.54307072679932866 0.62918631758930299 0.73959123115406300 0.95434524435815982 1.1684222173543095 1.4675750083934933 1.7271436442358192 2.0016660122294003 2.2932339453385944 2.6176873076273832 2.8560026574501229 3.3486095494864134 3.8343771518486038 ; 0.045193193127722665 0.20306196589405009 0.36243801852520696 0.49719941308329052 0.58099408636526650 0.65330573642944434 0.75247142521569388 0.88229034197398137 1.1396363470720907 1.3925832480734244 1.7400306598486259 2.0408987846670463 2.3542586880321705 2.6858485389644495 3.0359581057113161 3.3018559825629219 3.8696162806580485 4.4344239391781661 ; 0.055440070852056766 0.22770356260602162 0.39878550695296222 0.54992905062627462 0.64397656184762408 0.72500101333111844 0.83581302563643278 0.98157152401537739 1.2746159538260033 1.5383548738645014 1.9066601338637084 2.2527954527706209 2.5918406728107910 2.9470100314922676 3.3231510530956538 3.6085350113741965 4.2291469498236633 4.8538703326261157 ; 0.066611794409925956 0.25318619882378290 0.43875191440339062 0.60320205812908745 0.70671213074070216 0.79516768450544262 0.91820259451621133 1.0820689048935190 1.4088231436043384 1.6735809192152757 2.0814708284475945 2.4703694131437142 2.8259713602187411 3.2045730023162351 3.6115404434492016 3.9187862796693147 4.5958114425947452 5.2845736475995642 ; 0.090138977001691739 0.30532962445155964 0.51625506095108842 0.69620659332049295 0.81367356714339778 0.91864490538782717 1.0632284644528733 1.2545034379865827 1.6175868680663874 1.9253551478286908 2.3963109106551701 2.8189743455131855 3.2301147329929010 3.6604241994219677 4.1166254932910649 4.4712706977172703 5.2654234215862532 6.0787142281866222 ; 0.12498698176768640 0.36391505715225392 0.60068953016434690 0.79607778522811157 0.92457897228364372 1.0392922781070608 1.1990035121459717 1.4089338536352158 1.8089041545639402 2.1719868856064619 2.6773024672293437 3.1280100991703264 3.5948233036405952 4.0823256740421190 4.6125167636742814 5.0252207843521859 5.9480340239537774 6.8913148762835164 ; 0.16876679933642608 0.40907093804279548 0.65095451607252497 0.86594033966507544 1.0055337712590982 1.1286579184462759 1.2993503467794922 1.5240464890780714 1.9563125698345245 2.3413531024265204 2.8752079183344637 3.3612658165043499 3.8682462692594726 4.3905961982259454 4.9889186516585600 5.4483047395347270 6.4690282091149891 7.5097127740901577 ; 0.26151781648583838 0.49309330629346210 0.73382154402949684 0.96558081696725984 1.1143423028498833 1.2458163804740516 1.4272390780024640 1.6651129319604674 2.1274378912012191 2.5545019836840037 3.1303704911127355 3.6684997203824317 4.2334739129393073 4.8399552795268219 5.5058387608065251 6.0251579415991996 7.1767296840341972 8.3456283337596613 ; 0.33046540066447122 0.55987795173423771 0.79919928106208604 1.0339653829707589 1.1825455292624343 1.3150881322127006 1.4994298170300597 1.7474684934734719 2.2246475332304945 2.6708506040736526 3.2624186958814763 3.8207062531375020 4.4209410165635736 5.0780110693837193 5.7921095054943015 6.3452321714165585 7.5639494335709729 8.8004295470451641 ; 0.49239483638125264 0.73092876423971642 0.96897587563495413 1.2048975226044329 1.3558768968102552 1.4860080968753682 1.6655623935629389 1.9228161932527077 2.4262480466302576 2.8930123336631604 3.5234279231267140 4.1102003771694262 4.7680846808451083 5.5124729575862705 6.3451156116837142 6.9644648214072840 8.3057779570632668 9.6669942862119402 ; 0.62783472334015189 0.90157470127124462 1.1782014475480811 1.4114564089434618 1.5510674119854493 1.6767763401291269 1.8568595133849140 2.1020389518419349 2.5913069392963521 3.0734045486907271 3.7399252996710430 4.3641844134988164 5.0562060875896133 5.8416222417413906 6.7666858102123966 7.4380951504935711 8.8819040983781576 10.334795849996283 ; 0.76218803656282785 1.0701823686170060 1.3659000705192064 1.6005619740785697 1.7463479017938881 1.8812621442997421 2.0800377960937309 2.3244284203008481 2.7859402428311104 3.2680895812998787 3.9832238000847551 4.6560191869025411 5.3847688506983928 6.2240054673598584 7.1869497463660528 7.9158133005727995 9.4682033123813412 11.006822696293129 ; 0.88644046282532507 1.2270683602465808 1.5650479283480376 1.8532346859779703 1.9964573552945468 2.1278216471397262 2.3293292248021507 2.5808086835902562 3.0415575677462736 3.5238852240854910 4.2535878765078756 4.9989699278661677 5.7837593571061436 6.6828927490929466 7.6780658967106419 8.4447001603459011 10.090033452767198 11.704695652081636 ; 0.93470392719207784 1.2872523816906571 1.6364530567436950 1.9247881380143126 2.0813641614062659 2.2237575609921665 2.4291345720512232 2.6947062515834097 3.1686467529385096 3.6573386173967259 4.3710823655557371 5.1427434137751060 5.9528520091931245 6.8836690256864159 7.8979546463804029 8.6784332407463900 10.354711394867921 11.997013296437558 ; 1.0478396560049457 1.4258754354849841 1.7949789430155474 2.1084288149816457 2.2981401873277023 2.4660411982860837 2.7118160028245097 3.0237976013627152 3.5696314522135588 4.0937337166118946 4.7041901692449288 5.4906371482316558 6.3914701339812483 7.4261983348792118 8.5044483162383067 9.3165319618603828 11.048713661773226 12.749505799660485 ; 1.1467647427464549 1.5662633236085197 1.9894725214574422 2.3844050190559671 2.6370664941668620 2.8609257423422343 3.1743045061529709 3.5856342288203660 4.2099712434487708 4.8162618646410662 5.1920014628889906 5.9765382202384068 6.9578241297743837 8.0864402886156288 9.2239407745563611 10.053837466121651 11.810955907859675 13.552751289610043 ; 1.2664956205483044 1.7731176690161348 2.2912903992974814 2.7679515838253952 3.0572871475722856 3.3038225632701277 3.6309307038784295 4.0263797809002853 4.6060753333608728 5.0653397554500659 5.9947729755049517 6.8210860994758855 7.7632262528676259 8.9620977501078301 10.083870479736980 10.943218791390102 12.723898554566592 14.510611361848897 ; 1.4592257390876604 2.0493905448117573 2.6401264623709886 3.1580964446264059 3.4614954123040036 3.7161845240064051 4.0507472370397641 4.4598913181381663 5.1667701227253957 5.8433634783304287 6.8683894617138632 7.7380302693311656 8.5923061093928279 9.7285439881327793 10.914541301391784 11.809531280336987 13.708701502307811 15.598533327225205 ; 1.6852007667060620 2.3207331477744089 2.9525507473553945 3.5048859437628970 3.8311607524036360 4.1073535995087216 4.4752389804318495 4.9386279642306414 5.7954176773019856 6.6054371037098418 7.6799298541009611 8.5911973431974484 9.5585560754353214 10.610647581167557 11.745758021339432 12.634435528587224 14.633763258978776 16.665369877936328 ]; % Fuel Properties engine.fuel = class_REVS_fuel('FTAG 26781'); % Idle Speed engine.idle_speed_radps = class_REVS_dynamic_lookup; engine.idle_speed_radps.axis_1.signal = 'veh_spd_mps'; engine.idle_speed_radps.axis_1.breakpoints = [ 0.00000000000000000 10.000000000000000 ]; engine.idle_speed_radps.table = [ 60.737457969402662 ; 60.737457969402662 ]; % Pedal Calibration engine.pedal_map_type = enum_engine_pedal_map_type.max_engine_power; % Calibration Adjustment Factors % -- None --