Development of a High Performance Engine for a Formula SAE Racer

The paper reviews the theoretical and experimentaldevelopment of the engine powering the 2011 Formula SAEsingle seater of the University of Modena and Reggio Emilia(UNIMORE). The general design criteria followed by theUNIMORE team are discussed and compared to those chosenby other competitors. In particular, the reasons supporting theselection of the engine type (single cylinder by Husqvarna)are explained in details. The adoption of a single cylinder,instead of the more powerful four-in-line, required a muchbigger effort for getting an acceptable level of brake power.Therefore, the development was massively supported by CFDsimulation (both 1D and 3D) and by experiments. It wasfound that the most important design areas for the singlecylinder are: the intake system, including the restrictor (20mm), the intake runner and the plenum, and the muffler. GTPowerwas the main CFD tool used in the project: after theexperimental calibration of the base model, full loadsimulation have been carried out in order to optimize theengine geometric parameters, taking into account a number ofconstraints, decided by the team. The optimization goal wasnot just to have an engine as powerful as possible, but to findthe best package of both engine and vehicle.Besides full load steady calculations, also transient enginesimulations during a car acceleration have been performed.Engine-out noise was monitored too, in particular at thetesting conditions indicated by the competition rules.Finally, a complete performance characterization of theoptimized engine was predicted before starting the testing atthe dynamometer bed. These performance maps helped tospeed up the calibration process, and allowed the team also toget a rough estimation of the car fuel efficiency during theendurance event.