The turbocharger for a four-stroke gasoline engine of the Formula SAE racecar

Background: Any motorsport events consider some restrictions for engines, such as power restrictions or volumes restrictions, for the sake of safety. An air restrictor, which is a gauged orifice in an intake manifold, is one kind of used restrictors. The most efficient and permitted by competition regulations method of engine power increasing is turbocharging. Objective: Study of power increasing of a 1-cylinder four-stroke engine with an air restrictor at the intake by means of turbocharging. Methods: The study was conducted as simulation of operation of the 1-cylinder four-stroke engine with an air restrictor at the intake and a turbocharger. To simplify the simulation, the air restrictor was considered as a direct diffuser. The simulation was performed in the Ricardo WAVE software package, capable of performing complicated simulations of various intake and exhaust systems with or without restrictors or turbochargers. Results: The procedure of using the Ricardo WAVE software package for simulation of the 1-cylinder four-stroke gasoline engine is considered. Using the built mathematical model, simulation of main operation modes of the engine with a turbocharger, with and without a restrictor was performed in order to obtain its optimal characteristic curves. The scientific novelty lies in choosing and optimization the inlet nozzle length and using the restrictor for improvement the engine characteristic curves. Conclusions: The turbocharged air-restricted four-stroke engine of the Formula SAE racecar showed considerable advantages in comparison with the naturally aspirated one. Thus, the naturally aspirated engine has a maximal power of 31 kW and a maximal torque of 34 Nm, whereas the turbocharged engine has a maximal power of 40 kW and a maximal torque of 54 Nm that gives a significant improvement of racecar performance. Therefore, turbocharging is capable of not only solving problems caused by a restrictor but also improving key engine indicators significantly.