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In previous work, Gasoline Direct Injection Compression Ignition (GDCI) has demonstrated good potential for high fuel efficiency, low NOx, and low PM over the speed-load range using RON91 gasoline. In the current work, a four-cylinder, 1.8L engine was designed and built based on extensive simulations and single-cylinder engine tests. The engine features a pent roof combustion chamber, central-mounted injector, 15:1 compression ratio, and zero swirl and squish. A new piston was developed and matched with the injection system. The fuel injection, valvetrain, and boost systems were key technology enablers. Engine dynamometer tests were conducted at idle, part-load, and full-load operating conditions. For all operating conditions, the engine was operated with partially premixed compression ignition without mode switching or diffusion controlled combustion.

To meet future particulate number regulations, one path being investigated is higher fuel pressures for direct injection systems. At operating pressures of 30 MPa to 40 MPa, the fuel system components must be designed to withstand these pressures and additional power is required by the pump to pressurize the fuel to higher pressures than the nominal 15MPa to 20MPa in use today. This additional power to the pump can affect vehicle fuel economy, but may be partially offset by increases in combustion efficiency due to improved spray mixture preparation. This paper examines the impact on fuel economy from increased system fuel pressures from a combination of test results and simulations. A GDi pump and valvetrain model has been developed and correlated to existing pump torque measurements and subsequently used to predict the increase in torque and associated impact on fuel economy due to higher GDi system pressures.