BMW M4 Safety Car Debuts with Water Injection

BMW M division previews new water injection technology in the latest iteration of the BMW M4 Safety car.  Water injection while interesting in theory has its ups and downs.  A big downer typically is reliability.  However, when it works, it can provide substantial gains through the use of vaporizing water in an intake plenum to cool the intake charger after the heat exchanger becomes heat soaked. The water injection allows for more efficient charge air cooling and sensitive components can be operated with a higher boost pressure.  Water injection works by injecting a fine spray of water into the collector which will lower the tendency of the engine to knock, thus enabling the point of ignition to come closer to the optimum value.

As a method to reduce the temperature of the intake air of the new BMW M4, BMW developed a solution to inject a fine spray of water into the intake manifold which will lower the tendency of the engine to knock, thus enabling higher boost pressures and maintaining an optimum ignition point.

As a consequence, this creates a more effective combustion process and at the same time it diminishes the combustion temperature. Since the cool air has a higher density which increases the oxygen content inside the combustion chamber, this means the higher pressure during the combustion process will improve performance and torque. Moreover, the lower thermal strain on the components will increase their lifespan.

[tweetthis]New BMW M4 showing off factory water injection! [/tweetthis]

The necessary water is stored in a frost-proof five-liter tank located in the M4’s trunk which also incorporates the water pump, sensors and valves which are controlled by the engine’s electronics. The pump feeds water into the injectors at a ten-bar pressure while the volume of water provided depends on the load, engine speed and temperature in order to grant optimal water consumption. BMW M says the water tank must be refilled before any “rigorous action out on the racetrack” while in normal driving on public roads they estimate a water refill once every five stops for refueling without requiring any extra maintenance.

The new water injection allows for outstanding driving properties and impressive performance parameters on the race track for those who demand the most of their M4.

Discuss the Water Injection innovation here.