BMW Shows Off More Vehicles With Power-Boosting Water Injection

BMW held a presentation at its test center in Miramas, France during the past week where the automaker showed off a number of its upcoming powertrain technologies. The highlight was an i8 technology demonstrator fitted with a hydrogen fuel cell, and alongside it BMW showed a fuel cell-powered 5-Series Gran Turismo, a 2-Series Active Tourer plug-in hybrid prototype and this 1-Series prototype equipped with a power-boosting water injection system.

Water injection systems are nothing new, though we’ve rarely seen them in the world of production cars. This latest system is designed for turbocharged engines and creates a fine mist that is sprayed both in the intake manifold and directly into the cylinder where it helps cool the pressurized mix of air and fuel prior to combustion. This cooling effect makes for more efficient combustion, leading to increases in both power and efficiency. BMW quotes a 10 percent increase in power and 8 percent increase in efficiency.

What’s best is that the rate of efficiency is improved the harder you drive, helping reduce your average fuel consumption if you happen to be a sporty driver. That’s because the cooling effect reduces temperatures sufficiently to avoid any need to inject more fuel than required when operating at or near full throttle.

But there are gains to be had in the low and medium throttle range too. Lower temperatures reduce the risk of engine knock, allowing you to run a higher compression ratio. For example, in this 1-Series prototype, which packs a turbocharged 1.5-liter three-cylinder with water injection, the compression ratio was increased from 9.5:1 to 11.0:1.