Application of Numerical Simulation in Investigating Factors Effecting Torque Characteristics of Small Gasoline Engine

Intake and exhaust systems are significant components of an internal combustion engine. The design and operational variables of intake and exhaust systems are decisive to determine overall engine performance. The best engine overall performance can be obtained by proper design of the engine intake and exhaust systems. The effects of intake pipe length, intake valve timing, exhaust pipe length and exhaust valve timing on the torque characteristics were investigated based on the application of thermodynamic cycle simulation. The simulation model of a small gasoline engine was constructed. Using the constructed model, engine work processes with different intake pipe lengths, intake valve timings, exhaust pipe lengths and different exhaust valve timings were numerically calculated. The calculation results demonstrate that the intake pipe length, intake valve timing, exhaust pipe length and exhaust valve timing exert great influences on the engine torque characteristics. The engine torque can be improved by optimizing the intake and exhaust system parameters. The results provide theoretic guidance for the performance optimization of small gasoline engine.