Theissen says V10s need more restriction

Amid growing concerns that the air-intake and rev-limit restrictions on the old power units have not gone far enough in limiting the capabilities of V10s, Theissen is adamant that action needs to be taken.

"It is clear that the V10 which is limited or restricted in the way the regulations requested is significantly more powerful than a V8," he explained. "All the engine manufacturers had a look at that and came to the same conclusion.

"I would rate the power advantage, if you do a proper job restricting the V10, at more than 50bhp. It is somewhere between 50 and 100bhp, depending on how much effort you spend on that. That certainly creates an imbalance in terms of competitiveness."

And Theissen has backed up claims from Mercedes-Benz motorsport boss Norbert Haug that Toro Rosso have the chance of going for a podium finish in Bahrain this weekend.

"I think they can," he added. "I expect them among the top ten on the grid. Due to their higher torque they could catch another two cars right at the start and then they can go at their qualifying pace throughout the whole race."

When asked whether he believed action needed to be taken swiftly to rein back the performance of the V10s, Theissen said: "I think it would not be a bad idea."

The FIA have made no secret of the fact that they will change the restrictions on the V10 if they feel that the older power-units have an advantage over the V8s.

Autosport.com understands that the FIA have looked closely at engine performance data they have requested from Cosworth this weekend that compares the capabilities of their V8 and V10 power-units.

An FIA spokesman said: "We are monitoring the equivalency situation very closely."