DESIGN AND DEVELOPMENT OF A VARIABLE GEOMETRY INTAKE FOR A SINGLE-CYLINDER FSAE CAR

This research details the comprehensive design, manufacturing, analysis, and performance evaluation of a variable geometry intake system with a variable runner length for a cylinder-cooled SI engine, tailored to meet Formula SAE competition standards that include a mandatory 20mm air restrictor post-throttle body. The inlet valve closing time and the sound speed at different intake runner temperatures determine the optimal runner length. Harmonic analysis further refines these lengths across a broad rpm spectrum spanning from 2600 to 10000 rpm. The intake system's optimization includes CAD analysis and extensive CFD simulations conducted using ANSYS FLUENT 19.2 to refine the intake plenum's design. The plenum is constructed using Selective Laser Sintering (SLS), ensuring precise construction and performance integration. Dyno testing serves to validate the computational findings, revealing notable performance enhancements. The engine achieved a maximum volumetric efficiency of 101.856% at 5000 rpm and a volumetric efficiency of 97.606% at 8700 rpm, resulting in a peak power output of 29.6 hp, a 2 hp increase over the previous setup. Moreover, peak torque reached 25.1 Nm, from 4500 rpm to 8500 rpm, reflecting a 1.9 Nm improvement. As these results show, the variable geometry intake system improves the power, torque, and driving comfort of a naturally aspirated single-cylinder FSAE vehicle.