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Gasoline turbocharged direct injection (GTDI) engines, such as EcoBoost™ from Ford, are becoming established as a high value technology solution to improve passenger car and light truck fuel economy. Due to their high specific performance and excellent low-speed torque, improved fuel economy can be realized due to downsizing and downspeeding without sacrificing performance and driveability while meeting the most stringent future emissions standards with an inexpensive three-way catalyst. A logical and synergistic extension of the EcoBoost™ strategy is the use of E85 (approximately 85% ethanol and 15% gasoline) for knock mitigation. Direct injection of E85 is very effective in suppressing knock due to ethanol's high heat of vaporization - which increases the charge cooling benefit of direct injection - and inherently high octane rating. As a result, higher boost levels can be achieved while maintaining optimal combustion phasing giving high thermal efficiency.

Homogeneous Charge Compression Ignition (HCCI) combustion has the potential to produce low NOx and low particulate matter (PM) emissions while providing high efficiency. In HCCI combustion, the start of auto-ignition of premixed fuel and air depends on temperature, pressure, concentration history during the compression stroke, and the unique reaction kinetics of the fuel/air mixture. For these reasons, the choice of fuel has a significant impact on both engine design and control strategies. In this paper, ten (10) gasoline-like testing fuels, statistically representative of blends of four blending streams that spanned the ranges of selected fuel properties, were tested in a single cylinder engine equipped with a hydraulic variable valve train (VVT) and gasoline direct injection (GDI) system.

Intake charge preparation has strong effects on HCCI combustion, especially on the start of ignition. In this paper, the influence of different intake charge preparation modes on HCCI combustion in a single cylinder engine equipped with a hydraulic variable valve train (VVT) and gasoline direct injection (GDI) system is studied. By using VVT and GDI, three different intake charge preparation modes are implemented: re-compression early injection (RCEI), re-compression split injection (RCSI), and re-breathing early injection (RBEI). For each intake charge preparation mode, three engine operating conditions are investigated: 1.5 bar IMEP at 1000 rpm, 3 bar IMEP at 2000 rpm, and 6 bar/deg of maximum rate of pressure rise at 3000 rpm (IMEP's very near 3 bar). For all engine operating conditions and intake charge preparation modes, the combustion phasing, represented by the 50% mass fraction burned location (CA50), were fixed at 5 degrees after top dead center.