H2O replaces CO2
Water injection for gasoline engines

The Bosch WaterBoost system is an innovative development
for powertrain systems that taps into as yet unrealized efficiency
potential in combustion engines. This not only makes mobility more
fuel efficient and lowers emissions, but it also increases engine power.

Better engine performance – just add water
Bosch gives the combustion engine a boost

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Additional information about Water injection from Bosch.

Information package for manufacturers

Summary Water injection

Information package for drivers

Summary Water injection

Did you know that even advanced gasoline engines waste roughly a fifth of their fuel? This is in part because many of those systems inject gasoline in order to cool the engine. Bosch WaterBoost is a new injection system that sprays water instead of gasoline for engine cooling. The next turbocharged gasoline direct-injection engine that you see may very well include Bosch WaterBoost technology. This technology was first introduced in the world of racing, and has now been adapted for the open road.

up to

5% greater engine performance

without increasing engine displacement or boost pressure

up to

13% less fuel consumption

at higher acceleration or engine speeds


up to

4% less CO2 emitted

in the WLTC (Worldwide harmonized Light-duty Test Cycle)

With physics at its limits, now it's time to put chemistry into the mix
Innovative engine technology for more power and lower emissions

When a direct-injection engine with high levels of turbocharging is pushing its limits, bringing H2O into the mix of elements immediately pushes performance boundaries upward. The water actively cools the air-fuel mixture in the combustion chamber, which reduces harmful engine knocking, allows earlier ignition, and ultimately results in increased engine performance. The higher compression ratio in the engine also leads to a CO2 reduction of up to 4% in WLTC. Overall, the combustion process takes place at a better temperature and therefore in a more controlled fashion. Ignition happens sooner, which leads to a higher level of efficiency.

All the benefits of the Bosch WaterBoost system – the only one of its kind in the world – bring gasoline-driven powertrains to a new level of performance.

Fundamental for improved fuel efficiency
The benefits of turbo air cooling

It's an exciting challenge: as soon as the really fun driving starts, even the strongest engine breaks into a figurative sweat and responds with an increasing thirst for fuel. In these high-load situations, a welcome dose of refreshment is just the thing: a microfine spray from Bosch WaterBoost. Sprayed directly into the intake port, the fine mist of water droplets cools the hot combustion air down to a tolerable level.

Successful WaterBoost effect: even at high engine speeds, the engine doesn't get "out of breath," since it receives the explosive air-fuel mixture sooner. And yet the result is not uncontrolled misfiring. That's because targeted use of water also protects the components in the powertrain. Incidentally, filling an additional tank with roughly 1.5 gallons of the demineralized water lasts around 2,000 miles. And even if the water runs dry from time to time, there's no effect on how the vehicle operates.

Water provides more oxygen,
Improving engine performance

Horsepower is only truly powerful when it has enough room and air to give its driving force free rein. Whether or not turbocharging really gives direct-injection gasoline engines that extra kick forward is therefore decided in the highly compressed confines of the combustion chamber. Add in the fact that increasingly strict emissions guidelines of the past few years have not produced larger engine displacement; in fact, despite the rising overall demand for performance, displacement has actually gotten smaller.

If the horses under the hood are reined in more and more tightly, allowing them to "breathe" properly becomes even more important. That's why Bosch boosts oxygen saturation by cooling off the incoming charge air using water injection in the combustion chamber. The results are gratifying: driving is noticeably more dynamic and enjoyable and the engine freely shifts into gear for top performance. Up to 5% more horsepower with the same boost pressure and displacement? The proven technology makes this a thoroughly credible promise.

Engine to mechatronics: open the floodgates!
An overview of how WaterBoost works

Bosch aims to improve existing and proven direct-injection technology, now and tomorrow, without requiring OEMs to invest heavily in developing another part of the system. That's why Bosch deliberately designed WaterBoost as an auxiliary system that is easy to implement.

All that has to happen is to include the components needed for water injection in the structural plan and ensure that engine management incorporates them. Want a closer look at the technology? To the Bosch WaterBoost animation movie.