The Gasoline Direct Injection technology is one of the main approaches to make gasoline engines more efficient. Unfortunately they still suffer on a relatively bad mixture preparation quality compared to premixed MPI engines. Therefore it is important to find parameters/technical solutions which will help to optimise the mixture preparation quality.
One of the main parameters is the injector itself, the nozzle layout, another one is an increase of the injection pressure. Usual GDI layouts are made for injection pressures up to 200 bar. The investigations which will be presented by this paper are related to injection pressures up to 1000 bar. In addition to the pressure increase it will be presented how much the spray behaviour will be influenced by a fuel temperature increase up to around 350 °C. All investigations has been made with a prototype multi hole injector which could be combined with a fuel heating system, both made by IAV.
In a first step it will be discussed what the expected theoretical effects of a pressure and/or temperature increase on the spray behaviour will be. Results from optical spray vessel and hydraulic test bench investigations will be presented in a next step. The investigations has been made with pre heated fuel between 20 °C and 350 °C and injection pressures between 180 bar and 1000 bar. Both parameters has been combined and a matrix has been investigated. Finally it will be discussed and presented which influence the described parameters will have on the engine behaviour. Therefore some theoretical aspects will be discussed and results from single cylinder tests will be presented.