Numerical simulation was carried out to investigate the effect of transient in-cylinder air motion on fuel spray characteristics in a side-injection gasoline direct injection engine. KIVA-3V code with a fuel spray impingement model was used to simulate a swirl flow driven stratification for a late injection mode. For better understanding of in-cylinder air motion during the induction and compression strokes a flat piston and a bowled piston are compared with each other. Also a simplified simulation considering only the compression stroke was compared with the full simulation. As the high-pressure fuel spray jet flow is much stronger than ambient swirl and tumble flow in the present combustion system the spray development shows similar behavior in both simulations.