Technological Evolution of Spark Ignition Direct Injection Engine

Port fuel injection (PFI) requires a throttled engine, leading to significant pumping losses, particularly at part loads. Gasoline direct injection (GDI) engine offers benefit in terms of lower fuel consumption and higher power output. Due to these advantages, downsized, turbocharged, highly boosted, and GDI engines are increasingly preferred over PFI engines. However, GDI engines emit particulate matter (PM), which is not really a matter of concern in the case of PFI engines. This signifies that there exists a potential and need to control PM emissions from GDI engines. Particulates originating from GDI engines vary in size and categorized as coarse, fine, and ultra-fine particles. They also vary in composition and origin. In this chapter, pros and cons of GDI engine technology, its history, evolution, and key differences between PFI and GDI engine technology are discussed at length. Apart from this, three types of GDI engine combustion systems, namely air-guided, wall-guided, and spray-guided GDI combustion systems are also discussed. Particulate morphology and particle number (PN) emission from gasohol fueled engine vis-à-vis baseline gasoline fueled engine are also discussed in this chapter. An experiment to compare PN emissions and surface area distribution of particulates originating from gasohol fueled engine is also included.