BMW has unveiled a new M4 safety car for the 2015 MotoGP season, equipped
with an innovative water injection system.
In its production version, the sporting heart in the 2015 M4 Coupe delivers 425 hp (317 kW) and provides a maximum torque of 406 lb-ft (550 Nm) over a broad range. For use in the extremely performance-oriented world of MotoGP, the engineers at BMW M Division have equipped the high-performance power unit with an innovative water injection, thus considerably increasing the engine's performance. Water injection makes it possible to raise the upper performance limits, which have otherwise been restricted thermally. As well as increasing performance and torque, the innovative system in the BMW M4 MotoGP Safety Car also ensures better efficiency with benefits in terms of full-load consumption and exhaust emissions.
The water injection system will also be employed in a BMW M production model in the near future.
The price of a similarly speced M4 Coupe from the dealership would be around $95,000. Obviously, the price only includes factory-installed options and accessories. It doesn't include customized parts such as the fuel pump for overseas transport, water injection system, Recaro racing seats with harnesses, LED light bar, fire extinguisher and the carbon fiber rear spoiler.
Explained: BMW M Water Injection System
As explained by BMW, the performance achievable by a combustion engine is limited by various factors, including the process temperature in the combustion chamber. If this temperature is exceeded, the result is uncontrolled combustion (knocking) and thus a loss in performance and, in the worst case, expensive damage to the engine. This is particularly important when the engine is charged, as the intake air is already heated intensely in the turbocharger's supercharger. An intercooler does ensure that the temperature drops as necessary, but even that has its physical limits. Depending on design and dimensions of the cooling system and the car's aerodynamics, the intake air reaches temperatures that are just below the maximum permitted temperatures.
Increasing the supercharging pressure would exceed the knocking limit and is therefore not a viable means for increasing performance. BMW M Division has a solution: injecting a fine spray of water into the collector once more significantly reduces the temperature of the combustion air. The cooler supercharged air reduces the engine's tendency to knock, making it possible to bring the point of ignition forward and thus closer to the optimum value. This makes the combustion process more effective, whilst at the same time reducing the combustion temperature. On the other hand, cool air has a higher density which increases the oxygen content in the combustion chamber. This results in a higher mean pressure during the combustion process and in turn optimizes performance and torque. Finally, the effective internal cooling of the combustion chamber reduces the thermal strain on numerous performance-related components. This not only prevents damage to pistons, exhaust valves and catalytic converters, but also reduces the strain on the turbocharger, which is subjected to lower exhaust temperatures.