accommodated the "size zero" concept first conceived for use in the MP4-30 chassis, but with the RA617H moved to recreate the configuration first used by Mercedes in the PU106 series of engines. Honda's Formula One project manager Yusuke Hasegawa described the new architecture for the RA617H as "very high risk", justifying the choice as being the only way to catch up to Mercedes. Hasegawa also admitted that the technology implemented into the design—particularly around the combustion concept—was not entirely understood and that its potential would take time to fully realise. While discussing the issues with the engine mid-season, Hasegawa pointed to Honda's inability to recreate racing conditions during dyno testing; their underestimating the increased stresses placed on the engine as a result of the revised technical regulations introduced for the 2017 season; and severe vibrations affecting the transmission and oil tank as the root of the RA617H's problems. Following the Australian Grand Prix, Honda announced that work carried out between pre-season testing and the race meant that a majority of the issues that plagued them were fixed. Although the engine proved reliable over the race meeting, it had been detuned and the gearbox shift times increased to maintain reliability. Honda also revealed that a heavily revised "B-specification" engine was already in development and would be ready in as little as eight weeks, with both Honda and McLaren developing upgrades for successive Grands Prix to make up the deficit. At the Spanish Grand Prix, Honda brought an update to the power unit in the form of a revised intake system and mapping. Honda claimed this reduced the inherent drive train vibrations significantly allowing the gearbox and engine to run relatively normal in comparison to earlier races, this provided a small bump in power. Although Alonso had an excellent run in qualifying, gaining 7th position, the power unit still experienced reliability issues in early practice sessions with oil leaks and pressure issues causing stoppages. At the Azerbaijan Grand Prix, Honda introduced a redesigned MGU-H and turbo for both Alonso and Vandoorne claiming to have fixed the underlying reliability issues with those components. In addition to the new components, Honda brought one new spec engine which debuted a new fuel injection system to be used in tandem with a new BP fuel upgrade, further mapping improvements and various other minor updates for Alonso to use, however, due to the amount of penalties required