Azerbaijan Grand Prix: Red Bull & Toro Rosso first engine upgrade of season set for Baku race
Honda will have its first engine upgrade of 2019 for Red Bull and Toro Rosso at the Azerbaijan Grand Prix.
Technical director Toyoharu Tanabe said a reason for its early introduction had been the finding of a "quality control issue" with the previous engine.
This led to Toro Rosso's Daniil Kvyat retiring at the last race in China.
Tanabe said the "spec two" engine's main benefit was "improved durability and better reliability" but also with a "slight improvement in performance".
The upgrade could boost Red Bull's hopes of challenging for a win at the Baku street circuit, which includes what is effectively the longest straight on the calendar.
However, it is also likely to mean grid penalties for both Red Bull teams later in the season.
Each driver is limited to three power units per season, which means an engine is scheduled to do seven races. Baku is the fourth race of the season, so it is unlikely Honda can get through the rest of the season on just one further engine upgrade.
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Red Bull have had the third fastest car so far this season, behind Mercedes and Ferrari, but clever strategy and strong driving has seen Max Verstappen beat at least one Ferrari in two of the three races so far.
As a result, the Dutchman is third in the championship, 29 points behind leader Lewis Hamilton of Mercedes, two ahead of Ferrari's Sebastian Vettel and three in front of Vettel's team-mate Charles Leclerc.
Verstappen, who crashed out of the race in Baku last year with then-team-mate Daniel Ricciardo, said: ‟Baku is quite an interesting race because on a street circuit, you usually want to run a lot of downforce.
"Because of the long straights between the corners in Baku, you have to find a bit of a compromise - so that means you have quite low grip on the track and you slide around a bit.
"It's a lot of fun to drive and especially in the castle area, it's very narrow, but also it's really cool for pictures to look back at.
"It's a decent track for overtaking because of the long straight and especially with the DRS [overtaking] zone, so it's always an exciting weekend and a lot of things can happen. It's a big show and hopefully this year's race will make for a good story."