In order to develop engines with high performance and good fuel economy, with low noise and vibration, pistons getting smaller and lighter. So, a piston cooling jet started to be applied to cool-down piston temperature generally by targeting piston under crown to reinforce piston material fatigue strength of aluminum alloy. In this study, different piston oil jet target of cylinder bore is to be tested by comparing conventional under-crown target for evaluation piston cooling-down performance as well as NVH characteristic and fuel economy effectiveness.