Computer Simulation and Optimisation of an Intake Camshaft for a Restricted 600cc Four-Stroke Engine

• Main Authors: Taylor, James, McKee, Russell, McCullough, Geoffrey, Cunningham, Geoffrey, McCartan, Charlie
• Format: Report
• Language: English
• ISSN: 0148-7191; 2688-3627
• DOI: 10.4271/2006-32-0071

The use of inlet-restricted engines is commonplace in many motor sport applications and is particularly relevant for FSAE or Formula Student teams. The study outlined in this paper uses an engine simulation package, Virtual 4-Stroke, to predict the propagation of unsteady gas flow through an inlet-restricted 600cc four-stroke FSAE engine and hence optimise its geometry to maximise torque output. The Automated Design feature of the Virtual 4-Stroke package uses an intelligent Design-of-Experiments approach to obtain the optimum combination of a given set of geometric variables. This feature was used to find the engine configuration that maximises the torque output over the speed range 4000rpm to 12,000rpm. The variables investigated included the inlet pipe length, inlet plenum volume, inlet and exhaust camshaft opening time, duration and lift, with a total of 108 possible combinations. Provided there is an accurate baseline model, Virtual 4-Stroke can accurately predict the effect of a changed profile on the unsteady gas dynamics within the engine, and the resulting torque output. It was found that one of the most significant factors to affect the torque output was the duration of the intake camshaft. Based on the model predictions, a modified intake camshaft profile was therefore manufactured. Dynamometer testing provided good correlation with the simulations and improvements of 8% were found over the useable engine speed range from 5500rpm to 10,500rpm. Details of the model inputs, optimised camshaft profile and dynamometer test results are included and discussed.