Abstract
An independent study of a new design of the air intake system for a four-cylinder automobile engine is described. In multi-cylinder engines that share the same intake plenum chamber, interference between cylinders have a relevant influence in engine performance. One cylinder can be affected in a positive or negative way by the intake pressure wave originated in other cylinders. This paper investigates a 4L SI engine intake system that joints or separates the cylinders intake primary pipes to improve engine performance. The prototype intake system developed for this study has two plenum chambers, each connecting two cylinders. The two plenum chambers are kept separated in the engine speed ranges where cylinders interference hinders performance, and are interconnected when that interference is advantageous. Simulation and experimental results will be presented, compared and discussed, leading to a better understanding of the interference processes and torque improvement. The active control of interferences between cylinders has not been much explored in intake air processes studies in four cylinders layout (1-3). This work is a contribution to the knowledge on that area. The result of this study is a low cost intake system to improve engine performance in low/medium engine speeds, which can be associated with other geometry variation systems to improve overall engine performance. A 6.3% (experimental) and 6.7% (simulation) of torque improvement @ 3000 rpm have been reached in first stage of development. Further optimization using simulation tools have led to torque improvements of more than 10% in medium and high engine speeds.
Keywords: Internal combustion engines, intake system, manifold tuning, engine simulation, engine torque improvement.