Red Bull plan to run Ricciardo with the 'Spec C' Renault engine during Friday’s Free Practice sessions, before making a decision on whether to run it on both Ricciardo and Verstappen’s cars for the rest of the weekend. Renault's Engine Technical Director Remi Taffin said the unit can deliver around 0.3s per lap advantage on a circuit around Monza, the fastest track the drivers face during the 2018 season. However, he added that depends on the fuel used - Red Bull use ExxonMobil while Renault run BP/Castrol.
“I hope it's good,” said Ricciardo ahead of the weekend. “I'll try it on Friday and then we'll make a decision what we do with it. I always try not to expect too much – I think it's natural the last few years. I expect to see something, but whether it's one tenth, three tenths, we'll see. But if it is an improvement, it's better than not. I do expect an improvement from it, but I couldn't tell you in terms of lap time. A few tenths would be nice.”
Significantly, Red Bull have opted to fit the upgrade even before the Renault factory team themselves. When Ricciardo was asked whether he’d pushed to take the upgrade – and the resultant back-of-the-grid penalty it will entail – given that Red Bull’s third place in the constructors’ championship looks to be unassailable, he replied: “It was a team choice but I didn't disagree with it.
“I would love to start towards the front one year in Monza… but obviously looking at Singapore, that's a place you can't risk having a penalty, especially with the package we have, so in the end I agree with it.”
It’s the reliability of the Spec C engine that is the main reason why Renault and their other customer team, McLaren, have opted not to run it yet. Asked for his opinion on why Red Bull had decided to take the plunge with it, Verstappen replied: “We just want the most performance we can have. If it's really three tenths, that will be great. But we have to wait and see if it's going to be three tenths.
“Hopefully we can have a look at it tomorrow maybe, and see from there onwards what I'm going to do as well.”
Renault arguably face a tougher decision on whether to try the engine in their R.S.18 or not, given that they’re locked in a fierce battle with Haas over fourth place in the constructors’ standings – with Renault just 10 points up on the American squad heading into an Italian Grand Prix weekend where they again expect a tough midfield battle.
Despite that, Carlos Sainz maintained that he trusted the Renault works team's decision to stick to their 'Spec B' engine, a fresh unit of which was introduced at the last race, for Monza.
“If the decision of my team is not to run it because it's not reliable yet with our fuel that we use, it means we need to wait,” he said. “I want to finish races, I want to keep learning from the car, I want to keep making the car faster, and I think for the moment we need the 'B-Spec' and I hope that the 'B-Spec' is good enough [for us] to be fourth in the constructors' at the end of the year.”
Sainz also admitted that he would be keeping a close eye on how the 'Spec C' unit fared in the Red Bull, given that it is this engine that will most closely resemble the iteration that will be fitted in his McLaren when he joins the team in 2019.
“I'm sure the [Renault] engine guys from Viry are going to have a very close look at how the engine reacts and how it performs,” he said. “If that's two tenths, three tenths, it would be great news for us, because it's probably going to be our baseline for next year in McLaren and Renault. So I really hope it works.”