2011 European Grand Prix
Renault say the new restrictions on the use of exhaust-blown diffusers for this weekend’s race will affect the performance of all the cars.
From this weekend, teams will no longer be allowed to change their engine mappings between qualifying and the race.
This is intended to prevent them from using so-called ‘qualifying modes’ where exhaust gasses are used to increase downforce in the diffuser by burning fuel even when the driver is off the throttle.
Further restrictions will come into force at the British Grand Prix.
Renault’s technical director James Allison said: “We would have preferred to keep the status quo for the rest of the season.
“The FIA’s note will cause all teams (whether or not they use a blown floor) to change their operation.
“The headline changes for Silverstone are as follows: when the driver lifts his foot fully off the throttle pedal, then the ECU maps must be set up so that the engine (to all intents and purposes) closes the throttle – previously it was possible to configure the engine maps to leave the throttle open and reduce the engine power by other means.
“Furthermore, when the driver lifts fully off the throttle, the Engine Control Unit maps must be configured to cut off the fuel supply to the engine – this is intended to prevent so-called ‘hot blowing’ where the energy of the exhaust gas is increased by combustion.
“Finally, with immediate effect, it will no longer be possible to reprogram the ECU configuration between qualifying and the race in the expectation that this will discourage extreme ECU set-ups for qualifying – previously electronic access to the ECU under parc fermé conditions had been explicitly permitted.”
Allison played down claims this will disadvantage Renault more than other teams: “It is not easy to judge the effect of this change on our competitiveness.
“The loss for each blown floor car will come from two separate effects – how much downforce will you lose and, in addition, how much will the loss of this downforce upset the balance of the car.
“All blown floor cars will lose downforce under braking as a result of these new restrictions. Some teams will lose more and some teams less; it is hard to know exactly what relative loss Renault will suffer.
“However, it is possible that we will suffer less on the balance shift side of the equation because our forward exit exhausts produce their effect quite near the middle of the car. This means that as the exhaust blow waxes and wanes, it does not really disturb the aero balance of the car too much.
“With a rearward blower, the downforce from the exhaust is all generated at the rear axle. As the new rules reduce the blowing effect on corner entry much more than corner exit, it is possible that the rearward blowers will tend to suffer more nervousness under braking and more understeer on exit as a result of the new restrictions.
“We will find out at Silverstone!”
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Image © Renault/LAT