Enhanced Gasoline Engine Performance with Water Injection

Recently the focus on engine emissions has changed from normalised test cycles to real driving conditions. Over the past years, the same change of focus has been observed with regards to fuel consumption. Therefore optimal engine fuel economy and performance as well as minimal emissions are mandatory over the full range of engine speeds and loads.

Despite intercooling, turbocharged gasoline engines are limited in performance at the upper load and upper RPM range, mainly for component protection, leading to uncontrolled combustion and potentially even to engine damage.

For several decades, water injection is a known technology to cool down the air and fuel mixture in the cylinder and to better control combustion at high load and high RPM. However, water injection applications are still limited to specific applications (high performance cars, race cars, …) and low volumes. The main reason is the complexity and cost of managing water onboard a vehicle and delivering it to the injectors at the right pressure and dosing rate.

In this paper, an overview of available water injection concepts is shown, its potential impact on engine performance / emission / fuel economy is described and a study is made on how a water storage and delivery system could be optimized to make it viable/acceptable for every day vehicles.