McLaren racing director Eric Boullier says there is "clearly a gain" with the Honda power unit being run this week.
Honda introduced an upgraded power unit for the second pre-season test, with the same specification expected to be seen at the first race of the year in Australia. Speaking on Wednesday afternoon, Boullier said the early signs during the opening two days were encouraging regarding the power unit's performance.
"There is clearly a gain and it is good to see we have more potential coming," Boullier said. "It’s still very early days so we need to put more mileage, and there is more experience to be gained on how to use and exploit this. But so far, for sure, more potential."
And Boullier says Fernando Alonso - who completed over 90 laps with the new Honda power unit on Tuesday - was clearly pleased with the gains.
"His first comment was he was happy, he could feel a difference - compared to last year and compared to last week, actually. The comparison was straight forward and he was clearly happier.
"He will also be happier tomorrow, I guess, because we have been doing some mapping work since yesterday and the engine is better and better and better. But it is step by step because there is some reliability issue if you go too fast and too far."
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