Red Bull Racing boss Christian Horner wants more performance from Renault, but isn't sure the engine supplier can deliver the goods this year.
Red Bull has undoubtedly improved the performance of its RB13 since a substantial upgrade package was introduced at the Spanish GP back in May.
The development resolved many of the early season correlation issues which affected the RB13 and was followed by additional incremental aero changes in the early part of the summer before another significant upgrade was introduced in Hungary.
Unfortunately, Red Bull still lags its Ferrari and Mercedes rivals in the power unit department.
"The car is getting stronger and stronger under race conditions, and again it was a very competitive Grand Prix for us in Hungary," said Horner.
"So if we can just find that little bit more engine performance... You saw in qualifying that Max [Verstappen] was second-quickest in Q1 and Q2, but you get to the latter part of qualifying and you need that little bit extra to go with our major competitors."
Horner isn't sure however that Renault has the ability to extract more power from its engine given that resources are now mainly devoted to its 2018 power unit which it hopes will be on a par with its rivals.
"I think you need to speak to our engine supplier to understand what their thoughts are regarding engine introduction," Horner said.
Red Bull isn't expecting fireworks at the power-thirsty Spa venue at the end of the month, at least not in qualifying.
"Hopefully we can be reasonable there," he said. "Austria, we were reasonably competitive there - I think particularly on Sunday.
"On Saturday we are going to struggle. I can imagine us being fifth and sixth on the grid on Saturday and quicker than that on Sunday.
"The thing I can say about Spa is that you have the ability to overtake there."
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