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.