The first part of the paper gives an overview of the current status in fuel consumption gain of the GDI-vehicles previously launched on the European market.
In order to increase the potential for a further gain in specific fuel consumption the behaviour of 3 different combustion chamber layouts are studied.
The chamber layouts are aimed to adapt as well as possible to the particular requirements for application to a small displacement/small bore engine working in stratified lean conditions.
The paper continues with a description of the application that shows the different steps of a structured optimisation methodology for a 1.2 litre, small bore 4-cylinder engine.
The applications of an air-motion-guided and a wall-guided layout with a mechanically actuated valve train to the same combustion chamber are discussed. The potential of the air-motion-guided concept is enhanced through the introduction of an electromagnetic fully variable valve train.
The layouts are analysed through numerical simulation and tested either on a single cylinder or on a 4 cylinder engine test rig.
The paper concludes with a discussion of the impact of the improvement, which can be obtained through a combination of GDI with fully variable control systems for air-motion and low energy consuming auxiliary components.