Speed expecting to struggle at Silverstone

The restricted V10 engine has in the past left Toro Rosso complaining about the lack of top speed, something that is likely to hindered them quite a lot at the fast Silverstone circuit.

After finishing in 24th position in practice, Speed is under no illusions for the weekend.

"From what we have seen today and looking at the times, it's clear we are going to struggle a bit this weekend," said Speed.

"The car is working well, it's got good balance but we just don't have the power down the straightaways. Although it's much hotter than we expected, there are no problems on the tyre front," added the American, who spun during today's afternoon session.

"My spin? For some reason, I had a big problem with stability on rear brakes. I hit the brakes and suddenly I was facing the wrong way. So we still need to improve our rear end stability a bit."

Teammate Vitantonio Liuzzi was more optimistic after posting the 22nd fastest time.

"Quite a good day, but we still have some work to do on the handling of the car for tomorrow's qualifying, as we seemed to struggle a bit when running on new tyres," said Liuzzi. "As for race pace it's not too bad and we still have tomorrow morning to try and improve."