Rémi Taffin, Renault Sport F1 Head of Track Operations
As a result we need to provide optimum support throughout the rev range. Engine braking support is essential to provide a stable rear end into the corners and we anticipate this being even more crucial with the increased tyre wear rate this season. Equally, responsiveness out of the corners is important to carry speed onto the straights, while the top speed must not suffer on that long straight. Let’s not also forget the importance of KERS in Shanghai, as passing down the straight into T14 is one of the key overtaking opportunities.
The location of the Shanghai track also provides an unusual challenge. The circuit is situated in an industrial zone next to several factories, some of which produce concrete, which leads to a high concentration of dust particles in the air. Our air filters will be checked after each practice session and cleaned thoroughly to prevent blockages and, therefore, a relative loss of power.
The atmospheric conditions of Shanghai add to the difficulty of preparing this race. Ambient temperatures can be variable and there has been a variation of +/-10°C over the past six years. Temperatures can even oscillate drastically over the course of the weekend – in 2012 we saw a variant of around 5°C at some points. While lower temperatures mean a greater engine power output, the fuel consumption per lap however increases so engine engineers will be playing out a careful balancing act all weekend.
Shanghai: three corners in detail
Turns 1 - 4
The slowest complex on the track is the radial turn from T1 through to T4 where the track tightens on itself and the driver progressively loses speed. Engine braking support and driveability needs to be consistent here to give a stable rear end and avoid excessive wheel-spin, which costs both lap time and increases tyre wear. To reduce locking and improve the wear rate, engineers will map the engine to reduce engine braking when the driver lifts his foot off the pedal. This squares up the rear of the car, stops it from locking and reduces the tyre wear as a result. This phenomenon of reducing engine braking when the driver is off the throttle is called ‘overrun’.
Turns 12 and 13
Turns 12 and 13, which form the radial corner that leads onto the long straight, are the mirror image of the first complex. Again, creating car stability will decrease lap time, particularly when the tyres are worn or wearing down. Another means of creating stability is to change the pedal maps, ie. the percentage of torque delivered in relation to the percentage of pedal application. While the throttle application needs to correspond roughly to the torque delivered, small variations can make a real difference in the stability of the car. In this complex a soft pedal map – where the engine delivers relatively less torque at a low pedal position – is likely to be used so the driver initially has more modulation to avoid wheelspin, which wears the tyres unnecessarily.
Straight between T13 and T14
The straight between turns 13 and 14 is a touch over 1,300km and the RS27 will sit at full throttle for between 17 and 18 seconds – longer than it takes for a small airplane to take off! Given this period of time, which equates to about 20% of the lap time, it is essential to calibrate the engine and gear ratios to maximise acceleration without compromising maximum speed. Short ratios favour acceleration, which means getting up to speed in a shorter distance over the first part of the straight, while a longer top gear ratio permits higher maximum speed, which is important on the second part of the straight.