<div class="htmlview paragraph">In order to acquire low fuel consumption while the engine is running at low speeds and maintain the high power output of the traditional 4-valve engine at high speeds, multiple camshafts were applied in gasoline engines.</div> <div class="htmlview paragraph">An engine cycle simulation process of a gasoline engine with multiple camshaft profiles was presented in this paper. Engine cycle models were set up to describe external characteristic at 14 different speeds. A one-dimension model was used to describe the transient heat and mass transfer in pipes of the gasoline engine. In-cylinder combustion model was calibrated by engine test results. The simulation results showed a good agreement with engine testing results.</div> <div class="htmlview paragraph">Simulation and experimental research showed the volumetric efficiency and torque were low from 2500rpm to 3500rpm. Some parametrical study was presented for performance improvement of intermediate speeds, including changing induction-pipe length and putting off multiple camshafts shift. A method was put forward that an additional plenum connected to intake manifolds can enhance the volumetric efficiency and torque in the model at 3500rpm.</div>