 After the engine struggled with reliability issues throughout the first half of the season , Yasuhisa Arai declared himself happy with Honda 's progress following the British Grand Prix and announced that the development focus would switch to improving the performance of the RA615H ahead of the next round of planned updates at the Belgian Grand Prix , with plans for a wider range of updates spread out over the remainder of the season , with the Singapore Grand Prix earmarked as the first race that would be representative of the new engine 's performance . Honda predicted that the updated RA615H would produce enough horsepower to rival the Ferrari 059 / 4 engine . Despite being an average 13 @.@ 3 km / h ( 8 @.@ 3 mph ) slower than the fastest driver through the speed trap over the first half of the season , an analysis of the engine 's performance revealed that it had gradually reduced the deficit to the Renault Energy @-@ F1 2015 . Yasuhisa Arai went on to suggest that the engine had a 25 bhp ( 18 @.@ 6 kW ) advantage over Renault , but was still an estimated 50 bhp ( 37 @.@ 3 kW ) behind Mercedes . 
