 The updates introduced in Belgium included changes to the combustion chamber , intake and exhaust aimed at reducing stress on other engine components to allow them to operate at peak efficiency . An analysis of the team 's mechanical problems further suggested that there was a critical fault in the internal combustion chamber that was having a residual effect on the other components by placing undue stress on them , and an inefficient MGU @-@ H that was using energy faster than it could be harvested with the net effect that the engine would lose up to 160 bhp ( 120 kW ) halfway through a lap . During the race , the car was observed to be harvesting energy at the top of the Kemmel Straight — the fastest point on the circuit — while other cars were deploying their energy at the same place . Despite Arai 's insistence that the RA615H had an advantage over the Renault engine , Fernando Alonso estimated that the car was losing up to three seconds per lap to Mercedes at the Italian Grand Prix and was unable to attack or defend its position against the Renault @-@ powered Scuderia Toro Rosso cars , even with the drag reduction system ( DRS ) deployed . Alonso 's comments came amidst the first public signs of tension between McLaren and Honda with reports that the team had requested that Arai be removed from his position as Project Manager . An analysis of the development carried out by rival manufacturers revealed that both Mercedes and Ferrari had found an additional 40 bhp ( 29 @.@ 8 kW ) over the course of the season through the development of bespoke fuel blends and the reconfiguration of their combustion chambers to promote more efficient fuel burning , offsetting the gains made by Honda . 
