BMW M4 MotoGP safety car features engine with water injection system

Aside from the eye-catching livery and its complement of flashing lights, the BMW M4 that will be used as a safety car during the 2015 MotoGP season has one extra trick hidden up its sleeve, or under its bonnet to be more precise: a water injection system that is said to improve performance and cut fuel consumption by reducing combustion temperatures.

A problem for all internal combustion engines is knocking or uncontrolled combustion, which can occur whenever the temperature inside the combustion chamber exceeds a certain temperature. At its worst, knocking can be fatal for an engine.

Temperature control is doubly important in a forced induction motor, which is why many turbocharged engines employ an intercooler.

The M4 safety car's water injection system emits a fine spray of water into the engine's collector. According to BMW, this reduces the likelihood of knocking, decreases the combustion temperature, and increases the oxygen content as the air is cooler and denser. It also allows the engine to perform near its best even when only lower octane fuels are available.

The lower temperatures also help reduce strain on the turbocharger, as well as wear and tear to the pistons, exhaust valves and catalytic converters.

The water injection system is fed by a five litre tank located in the boot, which is linked to a pump that feeds water at 10 bar of pressure to the injectors as required. No word yet on how many kilos the water injection system adds to the M4's weight.

On the track, the water tank has to be filled up every time the car goes in for a fuel stop. During normal operation, however, the company estimates that the water store only need be replenished on every fifth visit to the petrol station.

If the water supply runs out or the system fails, the engine throttles back performance to ensure continued safe operation. In a nod to future production and those living in cold climates, the water tank is designed to be frost proof and any water in the pipes is sent back to the tank when the car is shut off.

While the production M4's 3.0-litre twin-turbo straight-six engine produces 317kW of power and 550Nm of torque without the aid of water injection, BMW claims that the water injected version increases performance and decreases fuel consumption by around eight percent.

The company states that the use of this technology in the MotoGP safety car is one step in a process which will eventually see it installed in showroom-bound cars.

Although no timeline has been given for the rollout of water injection technology into production vehicles, the company says that "following intense testing within the MotoGP World Championship, the water injection system will also be employed in a BMW M production model in the near future".

Other changes made to the safety car include the removal of the coupe's rear seat, and the fitting of Recaro buckets, a front splitter, rear diffuser, a carbonfibre spoiler and a performance exhaust setup.