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Bosch more broadly commercializing water injection system; up to 13% fuel savings under some conditions

Bosch is now more broadly commercializing its water injection system for turbocharged engines (earlier post). Bosch currently supplies water injection parts for the BMW M4 GTS—the first production vehicle to feature a water injection system. (Earlier post.) In the vehicle’s turbocharged six-cylinder engine, it offers improved performance and consumption even at full load.

Bosch’s WI system comprises a water pump; a water rail; and injectors which have been designed to handle the specific challenges arising as a result of operation with water. Particularly when accelerating quickly or driving on the freeway, the injection of additional water makes it possible to reduce fuel consumption by as much as 13% in highway conditions and 4% in normal driving (WLTC).


In a presentation in 2015 at the Vienna Motor Symposium on Bosch’s WI work, Dr. Rolf Bulander, chairman of the Bosch Mobility Solutions business sector and member of the board of management of Robert Bosch GmbH, explained that the improvement in fuel consumption results from cooling the charge to minimize/avoid fuel enrichment; mitigating knocking (premature denotation); and enabling an increased compression ratio. A port-injection WI system is low complexity and highly effective, he noted.


With our water injection, we show that the combustion engine still has some tricks up its sleeve.

—Dr. Rolf Bulander

The fuel economy offered by this Bosch technology comes especially to the fore in three- and four-cylinder downsized engines—precisely the kind of engines to be found under the hood of any average midsize car.

Water injection can also boost power by up to 5%, Bosch says. Earlier ignition angles mean that the engine is operated even more efficiently. On this basis, engineers can coax additional power out of the engine, even in powerful sports cars.

Only a small additional volume of water is needed: for every one hundred kilometers driven, only a few hundred milliliters 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 kilometers at the most.

If the tank should run empty, the engine will still run smoothly—albeit without the higher torque and lower consumption provided by water injection. The water flows back into its tank when the engine is stopped, where it may freeze in cold weather. The water is thawed following the re-start of the engine.



There is a six cycle engine that injects water to make steam.


is tap water sufficient or does it have to be distilled?


Six stroke Crower cycle would/should be useful recuperating design if produced.

The carburated 4 cycle 'do it your
self' conversions were no more than a washer bottle sized water tank mounted for gravity and vacuum feed, a flow restriction (jet).
Price for manifold injection conversion using small windscreen washer pump, solenoid tap, with G (torque) sensor and possibly reactive torque sensing via engine mount or just use the manifold vacuum. Complete with first 2 litres of magic sauce wholesale $20.00?
Should work like a charm.

An 'old timer'trick to clean up the cylinder head prior to removal for maintenance was to pour a steam of water through the intake with engine running. This resulted in effective decarbonising saving time cleaning post removal.

It is surprising just how much water could be flowed without damage or affecting the running.

Bosh have dotted the I's and crossed the t's to nail the parameters (calibrate and integrate with modern E.F.I. designs.


I assume you start with distilled but if you condense and filter the exhaust you can reduce particulates then just recycle the unburned hydrocarbons.

Big Al

Back in the 70's I installed a kt that was supposed to up your millage by drawing water from a reservoir to the carburetor. Advance your ignition and your ready to go! Did it work? I have to admit I didn't keep track of my mileage close enough to check.


If it gets people off diesel and back onto gasoline (in Europe) it would be no bad thing.
Obviously, we would all like to end up in EVs of some flavour, but it may take a while to get there, so this could help clean up our cities.

Henry Gibson

Bosch had the rights to sell Artemis technology which could save over half the fuel used by motor vehicles on the roads, but where are the automobiles?

In the early years of automobiles some countries had a horsepower tax. At first it was based partially on displacement.

Now a tax should be imposed on advertised and measured horsepower and horsepower hours and fuel consumption. Automobile drivers and owners should become aware that it is they who are releasing CO2 not the oil companies. This applies to house owners and dwellers. Every thing ever bought has a CO2 price. And people breathe out CO2 with every breath.

Ian Wright gave up on TESLA because he could achieve more cost effective CO2 reduction with heavy road vehicle hybrids that burned fuel.

The US government should not spend any more money on solar or wind, there should be requirements to use Artemis technology in automobiles and combined heat and cooling and power, CCHP, Co-generation, in buildings and communities for the cheapest quickest ways to reduce CO2 release in the US.


As ethanol is usually not produced dry, and is quite wet in fermentation, we should see this fuel, wet ethanol, promoted for turbo-engines as a booster in a separate tank.

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