McLaren's engine supplier Honda has confirmed that it has used three engine development tokens for its new power unit that will debut at the Belgian Grand Prix.
The use of the new engines means that Fernando Alonso and Jenson Button will get grid penalties this weekend.
The Japanese manufacturer has spent the last few weeks working on developments in a bid to improve its performance for the second half of the season.
The focus of its work has been on boost the combustion characteristics of its engine – which in turn will impact on improving its energy recovery.
Speaking over the summer break, Honda's motorsport boss Yasuhisa Arai said that his company was focused on key areas that it believed would deliver the best return.
“The most important area for us to concentrate on is the combustion,” he said. “Current regulations require high efficiency of the combustion so we want to change the characteristic with the chamber design and intake and exhaust system layout.
“Another issue we will be addressing is reducing mechanical friction by changing the gear train system along with the combustion.
“Not all of our upgrades will be in place for the Belgium Grand Prix; some parts will be applied for Spa and the rest during the weeks that follow. Our plan is to keep improving race-by-race for the remainder of the season.”
Honda had nine tokens for use during the season, and used two of them ahead of the Canadian Grand Prix.
With another three having been used for this weekend, it means it has another four for use later in the campaign.