MotoGP 2007: Criteria for Engine Optimization

The paper proposes some design criteria for the MotoGP engines, complying with the FIM 2007 Technical Regulations.Five configurations have been considered: 3-cylinder in-line, 4-cylinder in-line, and three V-engines with 4, 5 and 6 cylinders.All the analyzed solutions have been optimized from a fluid-dynamic point of view, by means of 1D engine cycle simulations. Then, the engines are compared in terms of full load performance, at steady conditions.Finally, the influence of engine performance, along with operations regularity and motorbike weight, is assessed by means of a lap time simulator, developed by the author on the base of real data. The best configurations turned out to be the 4-cylinder engines, while 3-cylinder and 5-cylinder are quite penalizing.The key of the 4-cylinder success is the good breathing capability and mechanical efficiency at high speed, yielding an optimum power to weight ratio, associated to a good engine regularity, i.e. a smooth response to throttle angle variations.