Effect of water injection on performance, gas emission and combustion noise of a 2-cylinder Turbocharged SI Engine: experimental and numerical analysis

Water Injection (WI) in the intake port of downsized boosted spark ignition (SI) engines is a promising solution to improve knock resistance and reduce over-fuelling at high loads. This paper reports an experimental and numerical investigation of WI effect on performance, gas emission and combustion noise in a downsized PFI twin-cylinder turbocharged SI engine. Both experimental and numerical data confirm that WI technology is able to significantly improve high-load Indicated Specific Fuel Consumption (ISFC) of the tested engine. Main drivers of ISFC improvements are the reduced over-fueling and increased spark advance, compatible with the absence of knock and allowable values of maximum in-cylinder pressure and turbine inlet temperature (TIT).