As the seventh of 21 rounds and one of the most power-sensitive circuits on the calendar, the Canadian Grand Prix is an obvious place to introduce the first major power unit update of the season. Three of the four engine manufacturers in Formula One have brought an engine update this weekend, with Mercedes missing out after discovering a "quality issue" ahead of the race weekend on its new batch of power units. Below is a guide to who has what ahead of this weekend.
Renault
As Red Bull's engine supplier, Renault's Canadian Grand Prix update is one of the most eagerly anticipated of the year. Daniel Ricciardo's victory in Monaco without a working MGU-K confirmed the widely-held belief that Red Bull's RB14 chassis is one of the most capable on the grid while also underlining the ongoing fragility of the Renault power unit. However, an upgrade in Canada -- rumoured to offer as much as 20bhp -- could provide the extra power the team has been looking for to fight for wins on a more regular basis. The upgrade is expected to be rolled out across all three Renault-supplied teams and is said to be worth 0.1s in lap time alone. While that may not sound huge, Red Bull chief engineer Paul Monaghan referred to it as "a notable step that we will take and exploit", although he emphasised that the performance gain would only be judged relative to the gains of rival teams.
Ferrari
In the opening rounds of the season, the Ferrari power unit has looked like the one to beat with rival teams impressed by the data they have seen in the SF71-H's GPS traces. How much of that was related to the way it was running its battery and MGU-K remains the source of much speculation, but an update will arrive for the works team this weekend nonetheless. Customer teams Haas and Sauber ran the updated Ferrari power unit for the first time in Monaco, but it is expected to be fitted to Sebastian Vettel's car this weekend -- Kimi Raikkonen's remains a question mark after he suffered an engine failure in Friday practice in Spain that put him out of sync with Ferrari's planned cycle of power units. Haas team principal Guenther Steiner said the upgrade had offered an advantage in Monaco, but claimed he was not privy to the full data from Ferrari. "For sure it was an upgrade but I don't know how big. It performed well so we have no doubt that it's better than the old one." However, Vettel was playing down expectations of another major step forward on Thursday: "It's hard to make any predictions [about the impact of the upgrade]. It also depends what other people might be doing here or not, which updates they might be doing. This track is a little bit different. It's more power sensitive so the engine can play a bigger role. But let's see where we are."
Honda
Red Bull won't just be looking at Renault's progress this weekend, it will also be keeping a close eye on Honda's. The Japanese manufacturer is looking to bring a significant performance update to its engine this weekend and it comes at an important moment as negotiations with Red Bull over a 2019 engine deal intensify. "We are introducing an updated PU for this event, fitting it to both cars," Honda technical director Toyoharu Tanabe said. "The updates are mainly to the ICE, focusing on improving performance." Keep an eye on the Toro Rosso's data through the speed traps to see how Honda is getting on.
Mercedes
Since the introduction of the turbo-hybrid engine formula in 2014, Mercedes has been the dominant force in F1. This year, however, it looks as though Ferrari has not only caught up but may have taken a lead in terms of engine performance. The team had hoped an upgrade from Brixworth this weekend would reverse that trend, but a late call was made to continue with the engines that have been used since the start of the year. The decision impacts customer teams Force India and Williams too and means all six Mercedes-powered cars will be running with high-mileage components on one of the most power-sensitive tracks on the calendar. "We've had to take the sensible decision to not bring the upgrade here, which is definitely unfortunate," Lewis Hamilton said. "We'll try and make do without but it will mean our performance is not the best. The goal was to make engine performance stay the same all the way through, but naturally you lose horsepower over races. If we're in several thousand kilometres in, it definitely would have lost performance. So at a power circuit, it will probably be magnified."