The limited-edition BMW M4 GTS comes with a unique feature developed by Bosch: water injection. This system is designed to increase fuel mileage by 13% and reduce CO2 emissions by 4%; it premiered on the BMW M4 GTS, announced last year as a special track-ready, higher-performance version of BMW's mid-size coupe.
While BMW introduced water injection to the motoring public, it did not have exclusive rights to it; only a head start. Bosch will make the system available to other manufacturers by 2019.
Water injection involves introducing a fine mist of distilled water into the engine intake ahead of fuel combustion. The spray reduces engine temperature and decreases knock. Ignition time is faster, fuel burn is more complete, and engine power is greater with fewer emissions.
This video includes animation that makes Bosch’s water injection system easier to visualize and understand.
As used on the BMW M4 GTS, BMW says water injection can bump the power by 5 percent. Bosch, on the other hand, says the primary goal is not faster cars, but less fuel usage and lower emissions. Fortunately, both are possible.
Not only that, but water injection can be used on engines of almost any size. Bosch project manager Fabiana Piazza told British automotive site Autocar that water injection can mean improved emissions and fuel efficiency on tiny cars up through supercars, but “the system works best on cars with an output of more than 80kw (107 horsepower) per liter.” She added, “We’re launching it into the market now as tighter legislation and new real driving emissions tests are increasing the importance of this technology in all cars.”
Piazza’s associate at Bosch and the project’s lead, Martin Frohnmaier, credited BMW with helping to develop the system. He added, “It’s a pretty normal thing to have a pilot customer to develop the system together before offering it to the market, and now as we launch to the wider market the system’s costs will come down as volume goes up.”
The BMW M4 GTS uses a five-liter tank in the trunk to hold the system’s water. When Bosch provides the system for other vehicles, the tank will be sized so as to require a refill about every 1800 miles. If the tank runs dry, the vehicle’s engine will still run perfectly well, but with less power and worse fuel mileage.
For the many markets that involve freezing temperatures, Bosch is still working on ways to heat the tanks.
Mass production, which means supplying automakers with large quantities of the water injection system, is planned for a 2019 start. While Bosch is already working with carmakers to integrate its water injection system into their vehicle development process, the work it has done with co-developer BMW and the M4 GTS probably means the system will show up in other BMW models long before we see it in other manufacturers’ cars and crossovers.
There are other water injection systems available as aftermarket products. Bosch’s industry leadership and the fact that BMW helped develop it and already uses it on one of its hottest cars is almost a guarantee that the system will be in very high demand once it is available.—Scott Blazey
[Photographs courtesy of Bosch and BMW AG. Video courtesy of Bosch.]
