• British Grand Prix

New exhaust clarification to hurt Red Bull

Christian Horner and Martin Whitmarsh fell out over the issue on Friday © Getty Images

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• Drivers:
• Christian Horner
• |
• Martin Whitmarsh

• Teams:
• McLaren
• |
• Red Bull

The FIA has made yet another change to Formula One's controversial exhaust regulations, which looks likely to hurt Red Bull at this weekend's British Grand Prix.

An hour before the final practice session at Silverstone the FIA issued another technical directive on how the teams are allowed to manage the engines off throttle in order to improve the performance of the diffuser. The latest directive will restrict the opening of the throttles to 10%, as originally planned, cancelling out the concession the FIA made for Renault engines on Friday that would have allowed it to run at 50% for reliability purposes.

On Friday a public row between Red Bull boss Christian Horner, who uses Renault engines, and McLaren boss Martin Whitmarsh, who uses Mercedes engines, highlighted how quickly the rules were changing with more than six technical directives now issued on the subject.

Whitmarsh was unhappy that Red Bull's Renault engine was running with its throttles 50% open, but Horner pointed out that the Mercedes was still allowed to inject fuel through the engine on the overrun (hot blowing instead of Renault's cold blowing). As things stand the Mercedes engine will still be allowed to use fuel on the overrun, again for reliability purposes.

However, the issue may not yet be resolved as Horner left the Red Bull motorhome to talk to the FIA's technical delegate Charlie Whiting ahead of the final practice session.

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