14. Gasoline Engine Boosting Systems

Boosting solutions such as turbochargers are one of the popular technologies in the development of IC engines. Turbochargers date back to their usage on aircraft engines in the early nineteenth century and started usage in heavy-duty Caterpillar engines in 1954. Later they were introduced in passenger car applications in the early 1960s and became more popular after the 1990s due to the usage of high-power density engines in passenger cars. Popular technologies in engine air management systems such as variable valve timing (VVT), supercharging, turbocharging and intercooling have significantly improved engine power-to-weight and power-to-displacement ratios. Turbocharging internal combustion engine is widely recognized as one of the best and most cost-effective technologies for the enhanced benefits in power density, low-end torque, fuel consumption (CO₂ emissions), transient performance etc. Basis the benefits of fuel efficiency from turbocharging, it is considered as one of the key technologies to adopt for CAFE standards (Corporate Average Fuel Economy) with downsized engines. Globally turbocharging has gained popularity and higher penetration year on year in diesel, gasoline, and bi-fuel /Natural gas engine types. The boosting system has been undergoing upgradation with various add-on features to meet performance and emission needs. The introduction of emission norms like RDE (Real Driving Emission) drives engines to optimise for a reduction in scavenging, maintain λ = 1 in full operations and usage of the gas particulate filter to meet the Particulate number (PN) limit. In gasoline engines, there is a need to incorporate advanced combustion technologies like Miller/Atkinson and Low-Pressure Exhaust Gas Recirculation (LPEGR), with lean burn combustion for improved fuel economy. In this chapter, the benefits and challenges of the turbocharger boosting system and its integration into the gasoline engine are described. Additionally, the simpler ways of modelling the engine air management system to help the selection of the right boosting solutions are described.