Renault confident its unique exhaust will fare well when rule tweak takes effect

As part of a mid-season rules clarification, teams will no longer be allowed to configure their engines so that exhaust gases continue to flow onto cars' diffusers and floors - helping aerodynamic performance - even when drivers lift off the throttle.

Allison believes that Renault's unique forward-exiting exhaust might withstand the effect of the rule tweak better than traditional rearward exhausts - though he still expects it to be a blow to performance.

"It is not easy to judge the effect of this change on our competitiveness," he said.

"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!"

Team boss Eric Boullier was unsure how Renault would stand when the revised rules come into effect, but was confident that his squad had done everything possible to prepare for the impact of the change.

"It's a complicated issue and difficult to state their exact impact just yet," said Boullier. "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."