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 2 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 2 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 2 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 2 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 data points exhibited unexpected behavior; specifically, at low speed 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('4a- 2018 Toyota 2.5L A25A-FKS Engine Tier 2 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('4a- 2018 Toyota 2.5L A25A-FKS Engine Tier 2 Fuel - Test Data.xlsx','Sheet','High Load Initial','VariableNamesLine',4,'VariableUnitsLine',5,'DataLine',6); hl_test_data.name = 'High Load Test Data'; keep = [1:4,6,9,10,13:37]; 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 26864');
disp(engine.fuel);
class_REVS_fuel with properties:
id: 'FTAG 26864'
description: 'Tier 2 Cert'
density_kgpL_15C: 0.7425
energy_density_MJpkg: 42.9080
carbon_weight_fraction: 0.8663
research_octane_number: 97.6000
motor_octane_number: 89
alcohol_pct_vol: 0
gCO2pgal: 8.9214e+03
energy_density_BTUplbm: 1.8447e+04
specific_gravity: 0.7432
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( 628 * convert.rpm2radps, 11.0);
0.1526
% Idle @ 577 RPM in gear measured fuel rate ~0.16 g/sec
engine.interp_fuel_gps( 577 * convert.rpm2radps, 15.9);
0.1579
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_Tier2.m', engine);
Engine Build: engine_2018_Toyota_A25AFKS_2L5_Tier2.m
% ALPHA ENGINE DEFINITION % Generated 29-Jul-2020 11:47:29 % Constructor engine = class_REVS_engine(); engine.name = '2018 Toyota 2.5L A25A-FKS Engine Tier 2 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 ; 103.12505234162977 ; 105.05060883873348 ; 121.15898176234263 ; 157.00483285440416 ; 211.47718214102289 ; 265.59208773845728 ; 313.74614017119956 ; 422.72974799570221 ; 470.72348049373937 ; 523.59877559829886 ; 691.15038378975441 ; 725.70790297924214 ; 760.26542216872997 ]; engine.full_throttle_torque_Nm = [ 0.00000000000000000 ; 114.50000000000000 ; 162.53695652173909 ; 179.76779661016951 ; 198.24725274725276 ; 214.35416666666671 ; 225.47875647668405 ; 220.25164835164833 ; 235.16847826086948 ; 236.85520833333331 ; 249.47051199999999 ; 219.02551316964789 ; 187.73615414541248 ; 0.00000000000000000 ]; % Minimum Torque Curve engine.closed_throttle_speed_radps = [ 0.00000000000000000 ; 105.03391438501875 ; 373.95424553230504 ; 470.50585975263135 ; 603.18578948924028 ; 760.26542216872997 ]; engine.closed_throttle_torque_Nm = [ -15.948686146731134 ; -22.000000000000000 ; -31.699999999999999 ; -38.600000000000001 ; -50.700000000000003 ; -59.749821315955444 ]; % Fuel Map engine.fuel_map_speed_radps = [ 0.00000000000000000 ; 40.540642121420589 ; 81.081284242841178 ; 108.90640491021287 ; 138.86135520377456 ; 156.88166247576345 ; 181.05631740574222 ; 211.24466377978447 ; 265.47141566072946 ; 313.66095091606940 ; 373.97057705343684 ; 422.27976929908095 ; 470.51933431633228 ; 518.81071920865065 ; 566.98449891520715 ; 603.19949327398876 ; 681.73245772135942 ; 760.26542216872997 ]; engine.fuel_map_torque_Nm = [ -62.737312381753220 ; -47.516666666666666 ; -37.300833333333330 ; -27.085000000000001 ; -12.425833333333333 ; 2.2333333333333334 ; 10.512499999999999 ; 17.696874999999999 ; 32.564285714285717 ; 45.700000000000003 ; 55.605000000000004 ; 72.757894736842104 ; 87.066666666666663 ; 91.799999999999997 ; 99.400000000000006 ; 113.13999999999999 ; 130.45999999999998 ; 140.84999999999999 ; 151.47248622589532 ; 161.29379940711465 ; 172.35006675567422 ; 189.16123665966307 ; 204.97210407128443 ; 215.87274746501913 ; 230.17722599761458 ; 246.06063179880729 ; 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 0.012623679004597602 0.092874172983330075 0.25827811073192158 0.42143094427348848 ; 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.036472128845502355 0.16458945144503140 0.29546175117465229 0.39289370247255745 0.59807455030884260 0.80074832313257172 ; 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.00000000000000000 0.0035959262960722415 0.042155020264574843 0.10112754434380657 0.17670796249244863 0.28827111353147644 0.42948823356174803 0.58027647068142429 0.69417883436704642 0.93890489022129020 1.1811677103263332 ; 0.00000000000000000 0.025958680890929169 0.066882129989041320 0.091666015839545936 0.11544214320613216 0.12869106714271827 0.14603681906634361 0.16900816971414387 0.22235113221461772 0.28971447543841694 0.40025231928587440 0.51743529524934628 0.65988167719300572 0.82317422183812961 0.99867490286258909 1.1338202122469760 1.4328555863504722 1.7308509319306855 ; 0.011419778982315212 0.080004717016239998 0.15168312795826300 0.19895450525419620 0.23936617519783843 0.26231462712324077 0.29454431600152137 0.33906995607230511 0.43071882332553918 0.53359860244755253 0.69731433690217359 0.85441718731221805 1.0309742629042109 1.2244663748917921 1.4294832850857526 1.5875067587343819 1.9387433698626448 2.2893807798445289 ; 0.025823853201822296 0.10298961244364190 0.18007132820074628 0.23164787774066531 0.28670873419781628 0.32159878922907692 0.36888659988111183 0.42946342084454947 0.54494179259470843 0.66946252600525047 0.86354957571160140 1.0419325371444432 1.2373779127762565 1.4492203860228470 1.6747340058931437 1.8484746323344561 2.2291428152169814 2.6092128656247606 ; 0.037332573832098474 0.12274216591870225 0.20614121167202581 0.26332996890506039 0.33093232902018699 0.37394559035221481 0.43248893234190067 0.50453043464686564 0.64298697819234740 0.78712152964606685 1.0069363640480544 1.2035193130087813 1.4148171163354217 1.6425827506273447 1.8876312142974907 2.0765249767042127 2.4827588815775248 2.8887904348517988 ; 0.055746993686289867 0.15869812410133957 0.26149363886146587 0.33289198901206213 0.42070743583338072 0.47742126299437815 0.55561110090110866 0.65393392922691873 0.84490224251477331 1.0266991674409880 1.2968765383766323 1.5332479083626276 1.7738811950420394 2.0349223455136696 2.3263366048403271 2.5507782043226217 3.0129198356036291 3.4770994968936342 ; 0.066959140738101983 0.19197241559094994 0.31685860018803008 0.40331100628780558 0.50726134050653049 0.57411455349625018 0.66672406870936030 0.78639202281499687 1.0113348476409829 1.2250974718771506 1.5425318366036096 1.8165513255880441 2.0930168229291879 2.3859064373031718 2.7117760145884366 2.9582955927411971 3.4858661488677938 4.0142706767263565 ; 0.074241171277086279 0.21879913177330637 0.36421396097529196 0.46487130748444205 0.58292855718699355 0.65473027721244803 0.75423231798537937 0.88863608091856472 1.1384494068640247 1.3757540568681266 1.7255959354638386 2.0309730384151825 2.3395762192107874 2.6661759093265212 3.0130342683460851 3.2711045173973301 3.8484387577523287 4.4295736698175210 ; 0.086911468722065899 0.26667405760947727 0.44625107423654276 0.56673392055802774 0.70639849511975095 0.79269299277881722 0.91076152460804871 1.0637596900324913 1.3699511875161796 1.6396250289146161 2.0411441073390222 2.4177587241922205 2.7651821962671215 3.1485481932375809 3.5489328450060782 3.8343292711040169 4.4997275092293938 5.1755696622830110 ; 0.098892291510938229 0.30272425392744268 0.50281458365227072 0.64037236677594944 0.79751152690003224 0.89747679724133644 1.0365906029910137 1.2164345023729508 1.5635718466929056 1.8711075897887459 2.3161588650871585 2.7148124532235758 3.1143504013903156 3.5380919672500535 3.9844072089688449 4.3242714505026152 5.0783304731603511 5.8312969930139937 ; 0.10325529950406534 0.31627909147688427 0.52622635709329935 0.66860410072501930 0.82908921485451181 0.93223025011340410 1.0761544003033530 1.2632806401391696 1.6222031565924577 1.9461101984425637 2.4053653386903076 2.8124666594803416 3.2284877798948859 3.6644848379883377 4.1265006324279323 4.4885545411997079 5.2725348430562917 6.0522140691349380 ; 0.11099809631206753 0.33872285073327491 0.56666689813110349 0.71488524705712320 0.88216189925558741 0.98947452042381190 1.1397088884598479 1.3370033744230985 1.7166527048755418 2.0640267668239813 2.5465369616372318 2.9706302139920533 3.4116030345336097 3.8664514354182864 4.3523207879198678 4.7540217508751841 5.5856447764821437 6.4096202174133348 ; 0.13603693565724398 0.37679887511896587 0.61963354213312805 0.78923562313299123 0.97786697384602994 1.0954687695435457 1.2579276190912578 1.4718088779922600 1.8996214793395854 2.2665967947745673 2.7921484061876254 3.2642584288124792 3.7497210083571413 4.2366990139042953 4.7553167799991867 5.2281534880863783 6.1530394507332673 7.0706345048293295 ; 0.23009010366580107 0.46925483792006439 0.71797861715249633 0.90135702833009901 1.1117299283894952 1.2446173463520698 1.4258091019282138 1.6623195765267931 2.1214282118635079 2.5323977817531276 3.0969976176659300 3.6375412632811548 4.1793742215209164 4.7377974108846717 5.3295843539924990 5.7995642937244671 6.8640149326070965 7.9474520002088918 ; 0.33037811069854761 0.57147436703264765 0.81675475892671967 0.99764205729738309 1.2101309648936283 1.3449657728023658 1.5326271307884514 1.7807978166678664 2.2610361913267343 2.7003406676521555 3.2919807517845090 3.8491208606211607 4.4310071412702134 5.0355588811361214 5.6722356343304341 6.1706309682261162 7.3185174878867274 8.4980436336106262 ; 0.45415546374504473 0.70568013570099497 0.95382727219190533 1.1251070113136168 1.3277005354802358 1.4555779109508755 1.6364038397927347 1.8878636585886228 2.4037204569390935 2.8777236707993850 3.4993790453241145 4.0811010764757683 4.6988796183253907 5.3409007699049225 6.0299416408576363 6.5698147754737022 7.8069355959510158 9.0754191304897720 ; 0.57940845481238212 0.84234000880536686 1.1136776179294348 1.2924666340439068 1.4521527649138426 1.5620848947555632 1.7312196427133164 1.9933450777245745 2.5172825204023752 3.0393854565543861 3.6911578259834434 4.3136428930409032 4.9618186740393231 5.6311532721147284 6.3781701871855914 6.9619030365424122 8.2818769573028455 9.6199106218004626 ; 0.72791284341419282 0.98796607577739415 1.2323771139476327 1.3857787854295196 1.5575814288720502 1.6774373363756345 1.8530510686137989 2.1262361871478159 2.6765722379913792 3.1988424897727223 3.9319285970306965 4.5937458692136737 5.2637609733761881 5.9921408359292689 6.8035595127955046 7.4368988445983133 8.8425399533377185 10.241071906527393 ; 0.93348421777998658 1.2113541330632123 1.4808434653447444 1.6591595063442859 1.8471332777006333 1.9693685428031862 2.1459397100082804 2.3862511879441688 2.9501105430385266 3.5068733091098410 4.2989194849900780 4.9925277125770444 5.6924297485372719 6.5992135353025478 7.5493083427841166 8.2582353788796166 9.7474874064540700 11.190850080282528 ; 1.1114338823727437 1.4606388882383117 1.8140251580043434 2.0614292475284635 2.3310327085570886 2.4929450635753541 2.7091049141624080 2.9875333561816499 3.4821420106997185 4.0376015150443889 4.7004084654886347 5.5141939308682666 6.3827809003420324 7.3693897728148618 8.3694525016025612 9.0997598320525448 10.600406094839673 12.060673055731430 ; 1.2526494159088677 1.6586992473488098 2.0708450033634334 2.3636049677413320 2.6936553924481204 2.9030253239797768 3.1966990632165770 3.5796308816800737 4.0685205202352259 4.5889727030357150 5.2642001359492125 6.0495650398219993 6.9399305450079636 7.9152415431884480 8.9366964088100183 9.6591488693775052 11.160378462767179 12.644535681741386 ; 1.4718295539887079 1.9525072511133248 2.4396819963973200 2.7799971872119431 3.1492771241721331 3.3695624795953592 3.6598243887828743 4.0012669700404322 4.5095277912456897 5.1291702811585322 6.0223902217451393 6.8150867278876435 7.6456333696853358 8.5389040985784721 9.5848180728023973 10.311777205296432 11.849859006916125 13.393987686140733 ; 1.7689675811327503 2.3056187846886558 2.8406670826550742 3.2036552839738013 3.5878670649719093 3.8146988932616663 4.1141199306089034 4.4793458861634630 5.1235525912177913 5.7621210584844782 6.6489851934062063 7.3833184454044440 8.1648355409700972 9.0490315260335841 10.085533414918656 10.871613920953168 12.543430383608438 14.208327501486536 ; 2.0917161412128746 2.6593713235123455 3.2220894774786162 3.6034333674217498 4.0098831744694747 4.2530828705010988 4.5784460549513346 4.9844510123708758 5.7188145353833875 6.3797365094910514 7.2321336850029141 7.9582225856337168 8.7488240170282001 9.6346679890011160 10.616076900153958 11.395457984316902 13.188353954219414 15.011517172971606 ]; % Fuel Properties engine.fuel = class_REVS_fuel('FTAG 26864'); % 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 --