Bahrain tech file - Renault

This weekend the 2006 Formula One season finally kicks-off in Bahrain. All the teams have already unpacked and ready to race. But, what are the demands of the Sakhir circuit for car and engine? The Renault F1 Team explains...

CHASSIS

Braking: Sakhir is a major challenge for the cars’ braking systems. Along with Montreal, this is the most demanding circuit of the year in terms of brake wear. The drivers slow from over 300 kph to first or second gear on three occasions. Furthermore, between turns 4 and 13, the corners follow each other in quick succession, which means the brakes never really have time to cool down. This can cause oxidisation of the brakes, and leads us to use the largest brake ducts of the year at this circuit.

Handling: The car must be well balanced to minimise oversteer exiting the slow corners, and to provide good braking stability, in particular for turns 10 and 13 where the drivers must begin turning in to the corner while still braking. This makes it important to find the best set-up compromise between a stable balance in the quick corners, and supple suspension in the slower sections to generate sufficient mechanical grip. To achieve this, we use bump rubbers which the car ‘sits on’ at high speed when the aero loadings are highest, and which it rises from in slower speed sections, allowing to the suspension to function fully and generate mechanical grip.

Tyres: Owing to the presence of sand on the track surface, the grip level of the circuit is always relatively low. This means the drivers must stick to the racing line as much as possible to keep the tyres clean. The circuit is not particularly demanding for the tyres in overall terms, but we pay close attention to the rear tyres, which do a lot of work under acceleration out of the slow corners.

ENGINE

The Bahraini Grand Prix is a very demanding race for the engines. They spend nearly 70% of the lap at full throttle, which puts the circuit among the top 5 of the year.

In the high temperatures, the engines experience ‘acoustic offset’. This means that as the temperature rises, the revs at which the engine develops its maximum power increase – by approx. 300 rpm for every 10°C. Previously, this was compensated in part by the use of variable intake trumpets. These are no longer allowed in 2006, which means the teams must forecast more accurately the ambient temperatures in order to fit the most appropriate length of trumpets. Variable trumpets previously allowed the teams to adapt to a wider range of temperatures, but fixed trumpets must be tuned more precisely to the prevailing conditions in order to generate maximum performance.

The primary risk for the engine remains the possible ingestion of sand, which would have be catastrophic for the pistons, piston rings or valves. The team therefore pays particular attention to air filters. Although certain materials may cost performance, they remain the most effective way of protecting the engine.

Temperatures are expected to be extremely high, which means that a successful car will be one which is able to provide sufficient cooling to the engine. Although the V8 is less demanding than the V10 in this area, the lower power also means that the percentage of the lap spent at full throttle has increased. As always, the optimum cooling level will provide the best possible compromise between cooling capacity and the cost of extra cooling in terms of aerodynamic performance.