Middle demands on the engine, with drivers at full throttle for between 55 and 60% of the lap at Sakhir
Sakhir: three corners in detail
Turns 1 & 2
The first corner is actually very tight as the driver brakes down from over 330kph to just over 60kph. Delivering the correct engine braking support to square up the rear of the car without creating too much ‘push’ is the aim as the driver will need a stable car under braking but must still be able to turn in. Engineers will do this by tweaking the engine maps.
After a slow exit from Turn 11 the track goes uphill into Turn 12 so as well rapidly switching direction, the car is also climbing. This therefore puts the oil system under pressure as the fluids in the system move from side to side very quickly but are also squashed down in the tank as the altitude increases. To avoid engine starvation, where the oil moves away from the pumps, engineers will check the minimum levels in practice.
Turns 14 & 15
The driver must get the exit of Turn 14 completely right as it falls slightly off camber as it enters Turn 15; running wide will compromise the acceleration down the long straight. Getting correct gear ratios helps in this respect, but finding the right balance is never easy as the circuit has a variety of corner speeds. Finding the sweet spot in the engine is therefore tricky, particularly on different fuel levels and pending DRS and KERS release patterns.
Rémi Taffin, Renault Sport F1 Head of Track Operations
Sakhir sits in the middle of the table for the demands it puts on the engine, with drivers at full throttle for between 55 and 60% of the lap. With a variety of speed corners, medium length straights and relatively long periods of time at full throttle, it is more external factors that affect preparation rather than the circuit itself. The high ambient temperatures have an obvious effect on cooling as the heat cannot dissipate from the engine efficiently. Where possible we try to avoid opening the bodywork as it has an adverse influence on the aerodynamic performance of the car. Instead, we try to get the lowest heat rejection into the car cooling system by operating the engine at higher water and oil temperatures, which eventually get the heat rejection down. However this means that the internal engine parts will run at a higher temperature, which needs careful monitoring.
Additionally when air temperature increases, the engine has to be tuned differently as the speed of sound also increases proportionally. This means the sound pressure waves created by the engine arrive at the inlet valve at a different time so the length of the trumpets (which regulate the intake of air into the engine via the airbox) need to be increased as well for perfect engine tuning – recreating a power curve that is equal to ‘normal’ ambient conditions.
The lack of water content in the dry desert atmosphere also stresses the engine. In fact, you can get an engine to ‘detonate’ if it is not managed correctly. This is a very destructive phenomenon basically consisting of an abnormal combustion of the air and the fuel in the engine, with subsequently massive stresses on the piston. To prevent this, ignition timing is tuned on the dynos as we reproduce the ambient conditions. We therefore protect the engine from detonating by setting the right amount of ignition timing, which is generally lower here.
Renault Sport F1