Red Bull Racing forced to alter engine mapping from Hungarian Grand Prix

Although Red Bull's cars were deemed legal by the race stewards in Germany last weekend, they are believed to have been operating with engine maps that had reduced torque in the mid RPM range.

The intention of the regulation prior to its clarification was to ensure that there was a linear relationship between the throttle position and the torque demand on the engine.

As expected, the FIA has thus issued a clarification of Article 5.5.3 within F1's technical regulations to the teams ahead of this weekend's race.

And although no official statement has been made public, AUTOSPORT understands the new version of the regulation insists teams will be limited in the amount of adjustments it can make to the engine torque map race- by-race.

According to the clarification, teams will be required to nominate one engine map - as a reference - that they used during the first four events of this season, which must then be approved by the governing body.

Once passed by the FIA, the engine torque curves above 6,000rpm must not vary by more than plus or minus two per cent from that reference map.

Teams will be allowed to make specific requests for changes when races take place in 'exceptional atmospheric conditions' however.

McLaren's managing director Jonathan Neale said on Wednesday that he could not quantify the impact the clarification would have on Red Bull's performance.

"The honest answer is I really don't know," Neale said. "None of us really know what it is that antagonised the FIA so much to provoke Jo Bauer into issuing the note he did on Sunday morning. It was quite an unusual step - I don't think the FIA would have referred to the stewards unless they had very serious concerns.

"It's really not for us to know or tell exactly what the Renault engine is doing in the Red Bull, and therefore how much advantage they get from it because it is an integrated performance package. But I know we are not the only ones on the grid who are looking at it very carefully."