The system injects a small, precisely-measured spray of water directly into the combustion chambers of a turbocharged 1.5-liter three-cylinder engine, a mill found in a number of BMW products including the MINI and the all-new X1. As it evaporates, the water extracts energy from its surroundings and it lowers the temperature inside the engine by up to 77 degrees Fahrenheit.
BMW’s fully-functional prototype shows that the process can improve fuel efficiency by up to 8 percent — especially at full throttle. It can reduce emissions by lowering the combustion temperature, reduce the risk of knock, and improve both power and torque by up to 10 percent. The Munich-based automaker points out that its ingenious water-injection system can be used all around the globe because it is compatible with low-octane gasoline.
Research is ongoing, but engineers predict water-injected engines will last longer because the process reduces the thermal load on vital components such as the pistons, the valves, the turbos, and the catalytic converter.
In every day driving conditions, the tank never needs to be filled up because the system automatically recovers condensed water from the A/C unit. Cars operating in unusually hot climates will need to be topped up occasionally, and store their water in a frost-proof tank.
BMW is still putting the final touches on its water-injection system. The technology will hit the market under the hood of the limited-edition M4 GTS that is expected to bow this August at the annual Pebbles Beach Concours d’Elegance, and it could make its regular-production debut when the next M5 arrives in time for the 2018 model year.
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