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Exhaust ban won't just affect downforce - Renault

ESPNF1 Staff
July 4, 2011 « Williams secures Renault engine deal for 2012 onwards | »
The Renault's exhausts exit at teh front of the sidepods © Sutton Images

Renault technical director James Allison is not fretting about the ban on off-throttle exhaust blown diffusers at the British Grand Prix.

It has been widely speculated that the R31 will be hit hardest by the ban as it is designed around a novel front-exiting exhaust that adds to its performance. However, Allison explained that the ban will not just affect the car's level of downforce but also its overall balance on corner entry - something he is confident Renault drivers will notice less.

"The headline changes for the Silverstone GP 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," he explained. "Furthermore, when the driver lifts fully off the throttle, the ECU 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."

Allison added: "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 be lost 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 LRGP 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 aerobalance 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!"

Nick Heidfeld is quietly confident Renault will not be hit hardest.

"With the new regulation changes it's going to be exciting; some people think nothing will change, some think that we will see changes but it is all just guesswork," he said. "A number of people think we will be one of the teams most badly hit [by the changes], but I doubt it. Let's see who's right!"

Team principal Eric Boullier added: "It's a complicated issue and difficult to state their exact impact just yet. What's certain is that we need to anticipate the changes to the regulations in the best way we can. It will definitely affect every single team, and it's up to us and our engineers to cope better than our competitors with the changes."