Water injection has recently found a home on the BMW M4 GTS, but the technology hasn’t really drifted down to more mundane metal yet. Bosch wants to change that, offering up its water injection technology to other manufacturers with the promise of more power and better fuel efficiency from compact turbocharged engines.
The main benefit of water injection lies in lowering combustion temperatures within the engine. Current compact turbocharged motors are pushing their limits, both in terms of performance and fuel efficiency. Adding water to the air/fuel mixture lifts those boundaries by actively lowering the temperature within the combustion chamber, allowing a higher compression ratio without the risk of knock.
According to Bosch, running a higher compression ratio makes for improved performance and around 4 percent less CO2 under test conditions. In the real world, the company says fuel savings could be up to 13 percent.
Although there are big potential benefits, the water injection system is reasonably simple in its operation. Water is drawn from a small tank, and a fine mist is sprayed directly into the intake port, where it evaporates. Bosch says 5 liters (1.32 gal) of demineralized water is enough to last around 3000 km (1864 mi) of regular driving, and when it runs dry the car will carry on operating as normal.
In a prototype BMW system, the water tank was refilled by condensation from the air conditioning system, but Bosch hasn’t mentioned any auto-refilling in its system. In the water-injected M4 GTS, the tank needs to be refilled manually by the driver.
Water injection isn’t just about efficiency, there are also performance benefits. The BMW M4 GTS got a 59 kW (80 hp) power boost over the conventional M4, some of which came thanks to the water-injection system. Bosch says manufacturers can expect a 5 percent boost in horsepower without any increase in displacement.
Bosch says it’s the only company out there with water injection technology, and is now offering it up to the world’s manufacturers. Check out the company’s explainer on water injection in the video below.
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