Red Bull Racing has gone back to Renault's B-Spec unit for this weekend's Russian Grand Prix, with Max Verstappen and Daniel Ricciardo expected to be hit with grid demotions.
The Milton Keynes-based outfit gave Renault's C-Spec power unit two thumbs up in Singapore, yet the team won't be running the engine in Sochi as a preventive decision linked to upcoming races in Brazil and Mexico.
The change will inevitable lead to grid penalties for Red Bull's drivers for Sunday's race, although the full extent of the set-back is not yet known.
On Thursday, Verstappen gave the low-down on the engine change, blaming it on... topography!
"Our C-spec cannot run at high altitude in Mexico and Brazil," said the Dutchman.
"We also knew since we took the C-spec on that we had to take another B at one point. I think this is the best place to do it. Also to have a few more spare parts in case something breaks."
Indeed, the thinner air associated with high-altitude venues, especially in Mexico City, would be detrimental to the engine's turbo and to it's MGU-H element, putting the unit's reliability at risk.
"The C-spec has a bit more power in qualifying but it's the same or maybe a little bit slower in the race. The recovery is not as good," he added.
"But it's all about qualifying so you would always want to take another tenth or one and a half tenth if the engine gives it to you. That's why we decided to take the C-spec."
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