Combustion performance of Gasoline Direct Injection(GDI) Engine was tested while it
was operated at several combustion chamber conditions. Two sets of injector and spark
positions were examined, and curved (or bowl) piston was used for guiding the spray
direction. When GDI engine was operated at the early injection condition, the evident
differences of combustion performance according to the combustion chamber shapes
could be observed. Using the visualized engine, we showed the spray processes and the
proof of film combustion phenomenon. The difference of wetted fuel amount could be
regarded as the reason of imep variation.