Turbo engines return to Silverstone today, more than 25 years after the Renault RS01 became the first turbocharged car to run in an F1 Grand Prix. Silverstone track puts Renault Energy F1-2014 through its paces with 60% of the lap taken at wide open throttle. Infiniti Red Bull Racing finish in top five in practice, Scuderia Toro Rosso within top ten.

Remi Taffin, head of track operations: Overall it's been a positive day that has consolidated the tests and procedural changes we have put in place since Austria and it gives us a good foundation going forward for the rest of the weekend.'

Silverstone is hard on the Power Units since more than half the track is taken at wide open throttle, with long periods of acceleration, particularly during the first half of the lap. It's a difficult circuit to map correctly, but we felt that our preparations and modifications since Austria have paid off. We saw a return to our usual business, with Red Bull the quickest team behind the Mercedes. While not ideal to be the second quickest cars, it does confirm that we are back to the status quo after the Austrian 'dip'.

We've had some issues, one with Maldonado in FP1. After Austria we identified a problem with the ignition that we believed had been corrected after the race. On running here, however, we saw that the problem was not 100% right so we reverted to our Plan B, which was to change the PU between sessions and conduct the running then.

Likewise with Caterham we experienced an ignition issue that we did not discover in time before FP1, but on changing some parts we could run through the programme as usual.

Despite the setbacks, overall it's been a positive day that has consolidated the tests and procedural changes we have put in place since Austria and it gives us a good foundation going forward for the rest of the weekend.

Check out our Friday gallery, here.