Renault is on the road to getting "100 per cent" from its new turbo V6 engine, according to operations chief Remi Taffin.
Earlier deep in pre-season crisis, the French marque has made great progress with its 'power unit' since then, but Taffin warns that there is still work to do.
"I would not say that we are optimistic; we are realistic," he is quoted by ICI Radio Canada.
Taffin said engine power is "not enormously important" at Barcelona and Monaco, the venues for the next two grands prix.
Still, Renault is using the three-week calendar break between the last race in China, and next weekend's Spanish Grand Prix, wisely.
"Maybe in Montreal we will be close to 100 per cent," said Taffin.
"Overall, this is promising, but we must not forget that we also need reliability," he added.
"It is obvious that we are the engine manufacturer that has probably introduced the most new parts for our engine, and they must be reliable," said Taffin.
"It is not only performance, we also need to finish."
At the same time, he also acknowledged the existing gap to the industry-leading F1 engine maker, Mercedes.
Asked to talk about the margin to the German marque, Taffin said: "It's hard to say. But what we can say is that Mercedes is faster on the straights and, for the moment, better for the entire lap.
"So I guess the German engine is better than ours. That said, there are factors other than the V6 itself - the turbo and the electrical components - where you can gain power.
"Also you cannot forget the fuel, and work is progressing well with Total," he added. "I think we will move forwards."