The project was aimed at developing new methodologies for the production of a high performance motorcycle engine, featured by low consumption and low emissions to comply with future emission standards.
The reference engine is a single cylinder with a 0.65 litre total swept volume, with high bore and short stroke so as to allow high revolution speed while maintaining reasonable average piston speed. In comparison with a multi-cylinder engine with same total displacement, a lower friction surface and a lower dead volume result, with noticeable benefit on mechanical efficiency at high speed.
The project was organised around three main tasks:
1. The preliminary project of the combustion chamber, aimed to the optimization of in-cylinder air motion and injector location, with the evaluation of the possibility of a double injection in the different operating conditions, and the choice of the start and duration of injection.
2. Design of the valve train system, with kinematics analysis and optimization of valve opening and closing strategies using a mechanical flexible variable valve timing device.
3. Development of a system for combustion diagnostics based on the use of a usual spark plug as a ionization current sensor. Such a system, entirely designed and realized at Istituto Motori, has been particularly aimed to knock detection, resulting as an effective alternative to conventional piezo-quartz sensors mounted into the combustion chamber.
The project achieved the following results:
- High volumetric compression ratio and high content of EGR;
- Direct petrol injection with an injection system that can carry out a dual injection per cycle;
- Adoption of a flexible mechanical valve command system;
- Power stoichiometric with trivalent catalytic converter and lambda sensor;
- Adoption of innovative sensors and closed-loop controls to optimize the ignition preventing the knock;
- Model based controls of the air-fuel ratio.