Formula Student is an international design competition, where students all over the world develop, design and build their own race car and afterwards compete with each other at different disciplines at events worldwide. The development process includes every module of the race car and the team of joanneum racing graz has focused on the powertrain since the beginning.
The following paper contains an overview of the reworking process of an in-line two-cylinder engine for the application in Formula Student. The intention was to increase the BMEP and at the same time reach a desired power/weight ratio of the engine. The process of selecting the most appropriate turbocharger by means of experimental testing on an engine dynamometer, as well as its optimization by means of numerical simulation, is outlined. Subsequently, the paper discusses the challenges regarding valve timing and finding the best trade-off between power and residual gas with the help of 1D-simulations. The necessary implementation of an intercooler and its efficiency optimization is also addressed. Finally, the calibration and optimization of the setup on the engine test bed is presented.
After the selection of the most suitable turbocharger for the engine and the reworking of its compressor side, it was possible to achieve a maximum boost pressure of 2.76 bar absolute. Charge air cooling and closed loop boost control guaranteed fast boost pressure build up. Together with the optimized cam timing, which reduced residual gas, and an increased compression ratio, the overall torque output of the engine resulted in 135 Nm at 4000 rpm and a maximum power of 63 kW at 6000 to 6500 rpm. The overall target of increasing the BMEP of the selected engine and at the same time achieving a lower power/weight ratio than the previous engine (FS133) was accomplished with a final value of 0.81 kW/kg.