Bosch said it was supplying water injection parts for BMW's M4 GTS, the first production vehicle to feature what the Tier One supplier described as "an innovative and groundbreaking water injection system".
In the vehicle's turbocharged six cylinder engine, it offers improved performance and consumption even at full load. Bosch said even advanced petrol engines waste roughly 20% of their fuel because, especially at high engine speeds, some of the petrol is used for cooling instead of for propulsion. Particularly when accelerating quickly or driving on the motorway, the injection of additional water makes it possible to reduce fuel consumption by up to 13%.
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"With our water injection, we show that the combustion engine still has some tricks up its sleeve," said Rolf Bulander, chairman of the Bosch Mobility Solutions business sector.
The fuel economy offered by this technology comes especially to the fore in three and four-cylinder downsized engines.
Water injection can make cars more powerful as well, Bosch said."[It] can deliver an extra kick in any turbocharged engine," said Stefan Seiberth, president of the supplier's petrol systems division. Earlier ignition angles mean that the engine is operated even more efficiently so engineers can coax additional power out of the engine, even in powerful sports cars.
The basis of this innovative engine technology is simply an engine must not be allowed to overheat. To stop this happening, additional fuel is injected into nearly every current petrol engine. This fuel evaporates, cooling parts of the engine block. With water injection, engineers have exploited this physical principle. Before the fuel ignites, a fine mist of water is injected into the intake duct. Water's high heat of vapourisation means that it provides effective cooling.
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By GlobalDataThis is also the reason only a small additional volume of water is needed: for every 100km (60 miles) driven, only a few hundred millilitres are necessary. As a result, the compact water tank that supplies the injection system with distilled water only has to be refilled every few thousand kilometres at the most.
And if the tank should run empty, the engine will still run smoothly, albeit without the higher torque and lower consumption.
In the future consumption test (WLTC), water injection makes it possible to save up to 4% fuel, Bosch claimed. In real driving conditions, even more is possible: here, fuel consumption can be reduced by up to 13% when accelerating quickly or driving on the freeway.
No water is left in the combustion chamber – it evaporates before combustion happens in the engine. All the water is expelled into the environment, together with the exhaust.
Bosch uses a port injection system, since it has clear technical advantages and costs less. This makes water injection suitable for large-scale production, as well as for many vehicle segments.
[Editor's note: aviation enthusiasts may recall demineralised water injection being used on early pure jet military and commercial aircraft, such as the Boeing 707, to increase take-off thrust – the planes were known for the plumes of black smoke emitted and the technology was not used for long]
