 Honda had previously competed in Formula One as a constructor when they purchased British American Racing in 2006 , before selling the team to Brawn GP ahead of the 2009 season . With the sport introducing a brand @-@ new engine formula in 2014 and Mercedes , their engine @-@ supplier , establishing their own team , McLaren sought a new engine supplier with a view to a long @-@ term relationship . The partnership with Honda was first announced in May 2013 , and the RA615H engine spent the next eighteen months in development . The team used Mercedes ' PU106A Hybrid engine in the McLaren MP4 @-@ 29 throughout the 2014 season . 
