Stuhldreher, M., Kim, Y., Kargul, J., Moskalik, A. et al., "Testing and benchmarking a 2014 GM Silverado 6L80 Six Speed Automatic Transmission," SAE Technical Paper 2017-01-5020, 2017.
As part of its midterm evaluation of the 2022-2025 light-duty GHG emissions rule, the Environmental Protection Agency (EPA) has been acquiring fuel efficiency data from testing of recent engines and vehicles. The benchmarking data are used as inputs to EPA’s Advanced Light Duty Powertrain and Hybrid Analysis (ALPHA) vehicle simulation model created to estimate greenhouse gas (GHG) emissions from light-duty vehicles. For complete powertrain modeling, ALPHA needs both detailed engine fuel consumption maps and transmission efficiency maps. Because EPA’s National Vehicle and Fuels Emissions Laboratory does not have transmission test facilities, it has previously used contractors for full characterization of transmission efficiency. To add to this benchmarking resource, EPA recently developed a more cost-effective in-house method capable of gathering a partial dataset sufficient to broadly characterize transmissions for ALPHA. This technique targets transmission operation observed during vehicle testing over the EPA city and highway drive cycles. This paper describes the method and test results of EPA’s partial transmission benchmarking process. The transmission test method involves installing both the engine and transmission in an engine dyno test cell with the engine wire harness tethered to its vehicle parked outside the test cell. The transmission gear selection was controlled by using the stock PRNDL control in manual mode. The torque converter lockup was enabled with a controller that could interrupt the signals and directly control the torque converter lockup clutch. The specific engine and transmission benchmarked used to develop this process was a 2014 Chevrolet Silverado with a 6-cylinder EcoTec 4.3L engine and its 6L80 six speed automatic transmission. The transmission dataset includes gear efficiencies, torque converter slippage and K factors, oil temperature and pressure, and OBD/epid CAN bus data.