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The hydrocarbon emission of a two-stroke engine can be partially decreased by scavenging improvement, but emission levels of a four-stroke engine can be achieved only by changing the mixture formation concept, specifically excluding the fuel from the scavenging process. Numerous research projects of gasoline direct injection - from liquid injection to air assisted systems - have been concentrated on two-stroke engines, determining the selection of the concepts which are suitable for series applications. This paper presents such a concept, based on the ram tuned injection: The system is characterized by a pressure modulation which can be adapted for an appropriate injection law, determining a suitable mixture formation for an engine with specific features. This electronically controlled injection system has been developed as a compact low cost unit for application to two-stroke engines with swept volumes of 50 cm3 and 125 cm3 which equip the two-wheeled vehicles.

Going from the example of the urban traffic in Europe, where the car use in town areas generally do not exceed 50 km/day, a series hybrid vehicle with light and compact thermal engine as an auxiliary power unit (APU) is demonstrated to be a promising concept. The paper describes such a configuration in base of a developed two-stroke engine with electronically controlled gasoline direct injection. The injection system is characterized by a high-pressure modulation obtained in base of the water hammer effect, which can be accurately adapted for a wide load and speed range of the engine. In this assembly the engine has extremely small dimensions and a dry weight of 8 kg, requiring a place which do not disturb the functions of the basic electric vehicle. The performances are convicting, the CO2 emission being reduced 3 times in comparison with a series four-stroke engine for the same car type, with an autonomy of 340 km and with a maximum speed of 100 km/h.