Renault won't make F1 engine upgrades until Russian GP

Renault has fallen further behind Mercedes and Ferrari this season, with a horsepower deficit leaving Red Bull a distant fourth in the constructors' championship.

Reliability has been a particular problem with both Daniel Ricciardo, who suffered another engine failure during second practice in Hungary, and Daniil Kvyat on their fifth engine of the season.

Renault has yet to use any of its allocation of 12 engine upgrade tokens, with reliability the focus in the first half of the season.

"I don't think anything is scheduled now before Sochi," said Horner on Friday.

"That is probably going to be the earliest we will see any form of development or use of tokens.

"So the engines we have at the moment are what we have to live with for the time being.

"Engines four and five are what the drivers have been using between Friday and Sunday racing.

"Unfortunately, Ricciardo has lost engine four, so he has only got engine five which came into service for the first time in Austria to get him through the next few races.

"Only time will tell if we can get to Sochi without incurring another penalty before introducing a new upgraded unit."

Horner insisted Renault is moving forward, but he conceded the long lead-times required for engine development means progress is slow.

"Renault would be the first to admit they are not happy with where performance or reliability has been with this engine," he said.

"They are making progress, they are making strides. The problem with the engines, unlike the chassis, is they are long lead-time items.

"Renault have got some strategic decisions to make over the coming weeks in terms of the direction they want to go not just for 2016 but for beyond that."

HONDA UPGRADE FOR SPA

Honda motorsport chief Yasuhisa Arai said McLaren can expect an upgraded engine at the first race after the summer break in Belgium.

The McLaren-Honda alliance has scored points just twice this season and is ninth in the constructors' championship.

Honda used two of its nine tokens ahead of the Canadian Grand Prix but has since focused on getting on top of its reliability issues before pursuing performance.

"From a technical point of view, the power unit will have a big upgrade targeted at improving the power output from Spa," said Arai.

"But it is difficult to judge how it will work on the actual track. So I want to get the answer in Spa."