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As part of the U.S. Environmental Protection Agency’s (EPA’s) continuing assessment of advanced light-duty automotive technologies to support the setting of appropriate national greenhouse gas standards and to evaluate the impact of new technologies on in- use emissions, a 2016 Honda Civic with a 4-cylinder 1.5-liter L15B7 turbocharged engine and continuously variable transmission (CVT) was benchmarked. The test method involved installing the engine and its CVT in an engine dynamometer test cell with the engine wiring harness tethered to its vehicle parked outside the test cell. Engine and transmission torque, fuel flow, key engine temperatures and pressures, and onboard diagnostics (OBD)/CAN bus data were recorded. This paper documents the test results for idle, low, medium and high load engine operation, as well as motoring torque, wide-open throttle torque and fuel consumption during transient operation using both EPA Tier 2 and Tier 3 test fuels. Particular attention is given to characterizing enrichment control during high load engine operation. Results are used to create complete engine fuel consumption and efficiency maps and estimate CO2 emissions using EPA’s ALPHA full vehicle simulation model, over regulatory drive cycles. The design and performance of the 1.5-liter Honda engine are compared to several other past, present, and future downsized-boosted engines and potential advancements are evaluated.

As part of the U.S. Environmental Protection Agency’s (EPA’s) continuing assessment of advanced light-duty automotive technologies in support of regulatory and compliance programs, a 2018 Toyota Camry A25A-FKS 4-cylinder, 2.5-liter, naturally aspirated, Atkinson Cycle engine with cooled exhaust gas recirculation (cEGR) was benchmarked. The engine was tested on an engine dynamometer with and without its 8-speed automatic transmission, and with the engine wiring harness tethered to a complete vehicle parked outside of the test cell. Engine and transmission torque, fuel flow, key engine temperatures and pressures, onboard diagnostics (OBD) data, and Controller Area Network (CAN) bus data were recorded. This paper documents the test results under idle, low, medium, and high load engine operation. Motoring torque, wide open throttle (WOT) torque and fuel consumption are measured during transient operation using both EPA Tier 2 and Tier 3 test fuels. The design and performance of this 2018 2.5-liter engine is described and compared to Toyota’s published data and to EPA’s previous projections of the efficiency of an Atkinson Cycle engine with cEGR. The Brake Thermal Efficiency (BTE) map for the Toyota A25A-FKS engine shows a peak efficiency near 40 percent, which is the highest value of any publicly available map for a non-hybrid production gasoline internal combustion (IC) engine designed to run on 91 RON fuel. Further improvement is possible by application of fixed discrete or full continuous cylinder deactivation, both of which are currently in production on other engines.

Ongoing work with methanol- and ethanol-fueled engines at the EPA’s National Vehicle and Fuel Emissions Laboratory has demonstrated improved brake thermal efficiencies over the baseline diesel engine and low steady state NOx, HC and CO, along with inherently low PM emissions. In addition, the engine is expected to have significant system cost advantages compared with a similar diesel, mainly by virtue of its low-pressure port fuel injection (PFI) system. While recognizing the considerable challenge associated with cold start, the alcohol-fueled engine nonetheless offers the advantages of being a more efficient, cleaner alternative to gasoline and diesel engines. The unique EPA engine used for this work is a turbocharged, PFI spark-ignited 1.9L, 4-cylinder engine with 19.5:1 compression ratio. The engine operates unthrottled using stoichiometric fueling from full power to near idle conditions, using exhaust gas recirculation (EGR) and intake manifold pressure to modulate engine load. As a result, the engine, operating on methanol fuel, demonstrates better than 40% brake thermal efficiency from 6.5 to 15 bar BMEP at speeds ranging from 1200 to 3500 rpm, while achieving low steady state emissions using conventional aftertreatment strategies. Similar emissions levels were realized with ethanol fuel, but with slightly higher BSFC due to reduced spark authority at this compression ratio. These characteristics make the engine attractive for hybrid vehicle applications, for which it was initially developed, yet the significant expansion of the high-efficiency islands suggest that it may have broader appeal to conventional powertrain systems. With further refinement, this clean, more efficient and less expensive alternative to today’s petroleum-based IC engines should be considered as a bridging technology to the possible future of hydrogen as a transportation fuel.