Wind of Change.
The regulations required the BMW Motorsport engineers to take a new approach to aerodynamics when developing the BMW M4 DTM. A shorter diffusor and the fact that the ride height has been increased in line with regulations, reduce downforce and ‘dirty air’. The flow topology around the car was completely revised. The front bumper now has a completely new shape and forms the starting point for the flow of the air around the car. The wing mirrors will have a more conventional design again in 2017 according to the regulations. Among the many clearly visible modifications are the even more prominent contouring of the side channel, the vent ducts on the rear wheel arches, which are being used for the first time, and the incredibly detailed design of the rear of the car.
The rear wing is also one of the more easily recognisable changes to the 2017 DTM cars. The Drag Reduction System (DRS) has been modified. Up until now, the rear wing consisted of just one profile and was lowered as one part when DRS was triggered. The rear wing of the new BMW M4 DTM is made up of two profiles, with the just the top profile tilting upwards when DRS is activated. Unlike before, the end plates no longer move with the wing. The range of adjustment for the system is up to 40 degrees for 2017, making it more efficient than last year.
The front splitter and underbody of the DTM cars are standard components, in accordance with the new regulations. The same goes for the floor panel, which is five millimetres thicker than before. The rear diffusor also has a completely new shape and is shorter and flatter than that of the previous model.
Over the course of the aerodynamic development of the new BMW M4 DTM in the BMW Group’s Aero Lab, the engineers had to be even more efficient than usual: they had just 50 days in which to test the new model in the wind tunnel and to optimise it. As a result, CFD calculations, simulations and the rapid prototyping of components from wind tunnel models played a more significant role.
Even more power.
When it comes to the engine, the DTM regulations for the 2017 season allow a larger diameter for the air restrictors, through which the engine draws in its combustion air. Having enlarged the air restrictors from 2 x 28 millimetres to 2 x 29 millimetres, the charge cycle was adapted accordingly. This increased the engine performance by about 25 hp to over 500 hp. Because the engine, now known as the P66/1, takes more cooling, due to the increased performance, the cooling air intakes towards the front of the car were also modified. As another consequence of the greater power, even more powerful and durable carbon-fibre brake disks are also used in the DTM in 2017.
In its final spec, the BMW V8 engine consists of almost 800 different components. In total, the powerhouse is made up of almost 4,000 individual parts. When designing the DTM power unit, BMW took full advantage of the technological know-how of the BMW Group. The high-tech foundry at the BMW plant in Landshut contributed the large castings, such as cylinder heads and crankcases. The processing of the castings, their coating, and any necessary thermal treatment, was performed by the appropriate specialist departments in Munich.
BMW Power continues to be transferred to the track via a six-speed, sequential racing transmission, which is operated pneumatically via shift paddles on the steering wheel. It has eleven transmission ratios, which allow the engineers and drivers to react to the circuit and engine characteristics when setting-up the car.