30% Fuel Economy Gain Seen for Gasoline Engine

Researchers have used available technologies to boost the fuel efficiency of a gasoline engine 30% in the lab. They say they are on track to build a commercially viable prototype by 2014.

The $25 million project is being co-funded by the U.S. Dept. of Energy under a four-year program called ACCESS (Advanced Combustion Concepts Enabling Systems and Solutions). About half the funding comes from program partners AVL, Bosch, Emitec, the University of Michigan and Stanford University.

The four-year effort, which began in 2010, aims to match the performance of a 3.6-liter V-6 gasoline engine with a 2.0-liter, four-cylinder turbocharged powerplant that delivers diesel-like fuel efficiency and a SULEV emission rating.

ACCESS engineering activities are headed by Hakan Yilmaz, chief engineer for gasoline systems at Robert Bosch GmbH. The system developed to date combines a high compression ratio with extra turbo boost, external exhaust gas recirculation, a multi-mode direct- and port-injection system, variable valve actuation, advanced electronic engine control, start-stop and thermal management.

An earlier iteration combined turbocharging to boost power with supercharging to maintain homogenous charge compression ignition (HCCI). Yilmaz says the current design uses a less expensive dual-stage turbocharger instead. The team also is considering whether to use combustion pressure sensors to help control the HCCI combustion process.

Current work is focused on developing control strategies for the engine. The team aims to test a working prototype of its "final" technology setup in a Cadillac CTS car two years from now.