Fuel Spray Velocity and Impingement Patterns Evaluated for Multiple Fuel Injection Nozzles: Hydrocarbon emissions during cold start contribute a significant fraction of the amount of hydrocarbon emitted over the entire emissions test cycle; therefore, technology that enables reduction of colds-start emissions is important. To develop such technology, experimental and mathematical studies have been conducted at various sites to help engineers better understand the mechanism of fuel spray behavior in an intake port. Keihin engineers investigated the behavior of fuel spray impinging on a wall for a fuel injection nozzle having spray characteristics different from others. According to the experimental results, changes in fuel spray velocity and droplet size were made by the different fuel spray characteristics, and engineers characterized these changes using the Weber number to study the trend.