Finding the ideal car set-up for Imola 20 Apr 2005
Giancarlo Fisichellas Renault race engineers, Alan Permane (chassis) and Fabrice Lom (engine) explain the technical requirements for achieving a fast lap around Imolas Enzo e Dino Ferrari circuit, venue for this weekend's San Marino Grand Prix.
Alan Permane: Imola places specific demands on car handling and although the circuit includes very few high-speed corners, we nevertheless pay particular attention to a number of specific areas. The car needs to perform well under braking and on initial turn in to the corners, while also providing good traction on corner exit. Engine power is critical, and we are well placed with the RS25 V10.
For the chassis, the numerous chicanes must be taken into account with both our set-ups, and how we run the cars through the weekend. In handling terms, a good change of direction at low and medium speeds is important, while the Variante Alta and Variante Bassa place a premium on riding the kerbs well - something the R25 does better than any other car we have produced.
The severe usage of the kerbs at the chicanes also makes reliability a key priority: if the car lands' while still at full or even partial throttle, the shock loads in the transmission can cause failures of the driveshafts or the gear ratios themselves. Equally, we pay particular attention to the underside of the car which takes severe impacts on the kerbs: this can break bodywork stays, or damage parts such as the front wing end plates and the front legality tray which are mounted low on the car. We will check these regularly when the car returns to the garage.
In terms of setting up the car, we run at the downforce levels that provide us with optimum lap-time - on our overall scale, this counts as high downforce. We are able to do this because overtaking is difficult at Imola, owing to the relatively short straights, and we do not need to compromise downforce levels to protect against overtaking in the race. In terms of springing the car, we have to find a compromise between riding the kerbs well - which would push us towards softer settings - and maintaining a sharp change of direction in the slower corners - which needs a stiffer set-up.
On the tyre side, the heavy traction demands mean that we will be monitoring rear tyre wear carefully for the race. The cool temperatures have seen some graining occur in the past, but in terms of overall wear, we expect the levels to be similar to Melbourne - the temperatures should be at the same sort of level, and the track surface is not particularly abrasive.
Fabrice Lom: Imola is a demanding circuit for an F1 engine: it includes a lot of hard acceleration from slow speeds, which means outright power is an important factor. The engines spend 62 percent of the lap at full throttle, a high value compared to the season average, and average engine speed is also relatively high.
The circuit layout does not include any particularly long straights: this means that moving parts such as the pistons, which are stressed by long periods at high revs, are not under undue strain. However, this is counterbalanced by the fact that climatic conditions are often cool: colder temperatures mean higher air density, which in turn sees the engine develop more power. Increased power output, of course, increases the strain placed on the V10.
The primary distinguishing characteristics of the Imola circuit are the numerous kerbs, and the fact the drivers use them as part of the racing line. As the cars jump' over them, the rear wheels leave the ground - exposing the engine to the risk of over-revving, or excessive use of the rev limiter. For the engine, hitting the limiter is a scenario to be avoided when possible because it increases the level of vibration on the engine. However, it is a preferable alternative to over-revving!
The presence of kerbs does not, however, force us to put the drivers under any unusual restrictions. We would never ask the drivers to take a corner slower in order to protect the engine, but we often study ways of changing the line through a corner in race conditions, or to change gear earlier, in order to minimise the risk to the engine.