Renault plans to introduce its version of the F-duct in the Belgian Grand Prix.
The team is currently the only front-running outfit not to have run the aero device, but team boss Eric Boullier says it is working on an example which he hopes will be used for the first time at Spa
"We have a two-step F-duct coming," Boullier said. "It depends on the schedule, Budapest is a high downforce track so we don't need to have it for that. Maybe we'll get it before, or very likely right after."
Chief race engineer Alan Permane defended the team's decision to delay its F-duct development much longer than its rivals.
"We've concentrated on other bits and bobs and put an awful lot of downforce on the car, so I still think it was the right strategic decision to not do one immediately like the other teams did," he said. However, Permane admitted that Renault has fallen back behind Mercedes and believes the F-duct will help the team challenge for fourth place in the constructors' championship.
"We should be fighting with the Ferraris and Mercedes," he said. "Realistically, we're just at the back of that group at the moment. We had edged ahead of Mercedes but they've done a very good job – they were very quick at Silverstone and they're ahead of us again now.
"We need a little bit more and when we get our F-duct online that should help. That won't be for another couple of races, but that's all we're missing compared to other people.
"I think we've over-performed, honestly. We've made the most of the car and made the most of the opportunities presented to us in races, and I hope we can carry on doing that for the rest of the year. In the absence of winning, our goal is to beat Mercedes and be fourth quickest."