Oct 2015 - BMW today announced the new 2016 BMW M4 GTS giving BMW M GmbH a new and exclusive technological masterpiece which elevates the potential of the BMW M4 Coupe to an impressive new level.
With its powerful, motorsport-inspired looks and high-performance technology, the BMW M4 GTS has its sights set squarely on the race track. Thanks to an innovative water injection system helping boost power to 493 bHP and track ready chassis, this Special Edition M vehicle recorded a lap time of 7 minutes 28 seconds around the legendary Nürburgring-Nordschleife, the world’s most challenging race circuit, making a clear statement about this model’s exceptional dynamic abilities. At the same time, the sharpest BMW M4 of all can also hold its own on public roads. BMW M GmbH is launching the BMW M4 GTS in a special edition limited to 700 units worldwide, with 300 units of this high-performance Special Edition M4 available for the first time in the US market. In so doing, it is highlighting the innovative flair of the BMW M engineers in developing trailblazing M technologies on the powertrain, chassis and lightweight construction fronts.
“Special Edition models sharpen the character of the BMW M brand and embody an emotionally rich and exclusive driving experience. We’ve taken a radical route with the set-up of the BMW M4 GTS to create a sports machine for the race track that delivers top-end dynamics and inspirational performance. It allows us to demonstrate what is possible today with a road-legal car. Owners can drive their BMW M4 GTS to circuits such as Spa-Francorchamps, the Nürburgring or Laguna Seca – for clubsport events, for example – and then set lap times there that raise the bar to extremely high levels for road-legal cars.” says Frank van Meel, CEO of BMW M GmbH.
Performance boost courtesy of innovative water injection.
At the heart of each and every BMW M model is its engine. The BMW M4 GTS uses the multi-award-winning M TwinPower Turbo 6-cylinder in-line engine from the BMW M4, capable of 7,600 rpm but adds innovative water injection technology to give the 3.0-liter unit a substantial power boost. Unusually high-revving for a turbocharged engine, it offers linear power delivery over a wide engine speed range. An innovative water injection system, used for the first time in a road car, takes this 6-cylinder in-line turbocharged unit to new performance heights by relaxing the thermal constraints on power and torque. The system has already proved itself on race tracks around the world on board the BMW M4 MotoGP Safety Car, this year’s lead safety car in the world’s top motorcycle racing series.
The engine develops its maximum power of 493 bHP – an increase of 16 percent over the BMW M4 – at 6,250 rpm. Peak torque has been increased by 10 percent to 442 lb-ft, and is maintained over a very wide rev band (4,000 rpm to 5,500 rpm). It accelerates from a standstill to 60 mph in a mere 3.7 seconds, on the way to a governed top speed of 189.5 mph. Despite the significant extra power, the engine also excels on fuel efficiency, providing similar levels to those found in the BMW M4 Coupe.
Innovative water injection system.
The BMW M4 GTS is the first production road car to be fitted with a trailblazing water injection system. With this arrangement, the BMW M engineers have utilized the principle that water absorbs heat from the surrounding air when it changes phases. Water is injected as a fine spray into the intake manifold plenum chamber where it evaporates (phase change), significantly lowering the temperature of the intake air. This action reduces the final compression temperature in the combustion chamber, minimizes the risk of knock and allows the turbocharged engine to operate with higher boost pressure and advanced spark timing. The result is increased power and torque, and a substantial improvement in efficiency. Despite the extra power output, thermal stress on all performance-related components is reduced. All of these features ultimately help to diminish wear and prolong engine life.
The benefits of water injection can be utilized in various ways, depending on engine and vehicle type. In particular the engineers have considerable latitude when deciding how to balance their priorities between increased power and fuel efficiency. If water injection is taken into account in the design of a high-performance engine right from the start, it is possible to use turbochargers with a higher boost ratio and compression ratio. At the same time, power losses due to an increase in ambient temperature (> 68° F) can be compensated by increasing the amount of water injected.
The engineering behind intake temperature.
The output of an internal combustion engine is physically limited by the operating temperature in the combustion chamber. If a given operating temperature is exceeded, this will result in uncontrolled combustion (knock), leading to power losses and, in the worst case, to severe engine damage. This is particularly relevant in the case of turbocharged engines, where the intake air is heated in the turbocharger compressor to as much as 320° F. Although intercooling can be used to cool the pressurized air, the capacity of intercooling systems is physically limited. Depending on the design and size of the system, and the aerodynamics of the vehicle, it is only possible to use an intercooler to reduce the intake air temperature by as much as 160° F before it enters the plenum chamber. This means that simply rising engine power by increasing boost pressure is not an option as it would mean exceeding the knock threshold.
This is where the BMW M division’s solution comes in: if water is injected in a fine spray mist into the intake plenum chamber, it is possible to reduce the temperature of the intake air by an additional 80° F. This further cooling of the pressurized air makes it possible to advance the spark timing closer to the optimal value. This results in a more efficient combustion process, while at the same time reducing the final combustion temperature. An additional advantage is the fact that cool air is more dense which increases the amount of oxygen in the combustion mixture and results in a higher mean combustion pressure, leading to optimized power and torque development. This efficient in-cylinder cooling system also reduces the thermal stress on a broad range of components including not only the pistons, exhaust valves and catalytic converter but also, due to the lower exhaust gas temperatures, the turbocharger.