De Cesare, M., Cavina, N., and Paiano, L., "Technology Comparison for Spark Ignition Engines of New Generation," SAE Int. J. Engines 10(5):2513-2534, 2017.
New gasoline engine design is highly influenced by CO2 and emission limits defined by legislations, the demand for real conditions fuel economy, higher torque, higher specific power and lower cost. To reach the requirements coming from the end-users and legislations, especially for SI engines, several technologies are available, such as downsizing, including turbocharging in combination with direct injection. These technologies allow to solve the main issues of gasoline engines in terms of efficiency and performance which are knocking, part-load losses, and thermal stress at high power conditions. Moreover, other possibilities are under evaluation to allow further steps of enhancement for the even more challenging requirements. However, the benefits and costs given by the mix of these technologies must be accurately evaluated by means of objective tools and procedures in order to choose among the best alternatives. This work presents a comparison at concept level between the main technologies that are currently being developed, considering not only the technical benefits, but also their cost-effectiveness. The analysis is carried out on the basis of studies from the technical literature, integrating missing data by means of evaluations performed with engine-vehicle simplified models, considering the most important powertrain architectures.