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In this report, the effect of injection specification, such as droplet size, lengths of nozzle tip and spray angle, on the engine performance was investigated using a 1.2 L port fuel injection (PFI) four-cylinder gasoline engine. The experimental conditions were selected to cover the daily operating mode, including the cold start and catalyst heating process. The experiments were conducted by varying not only the injectors but also the injection timing which was shifted from the exhaust to intake stroke. The results were evaluated by the fuel consumption and exhaust gas emissions. When these tests were conducted on a production engine, a carefully designed tumble generator was installed at the intake port to enhance the intake air flow. As a result, the injection specifications showed a potential to obtain less fuel consumption and lower engine-out emissions was evaluated.