Honda's upgraded engine for the US Grand Prix will offer more power from the V6 turbo but will still be handicapped by the power unit's ERS deployment issues.

Honda has faced a season-long struggle since returning as McLaren's engine supplier this year, with its V6 turbo hybrid proving to be underpowered and unreliable. The last of Honda's in-season performance updates debuted in first practice for the Russian Grand Prix, but McLaren made a strategic decision not to race the upgrade until the US Grand Prix next weekend.

However, the upgrade is focused on improving the V6 engine and Honda's ongoing problems with recovering and deploying energy via its ERS will not be addressed until next season.

"There will be progress on power because we upgraded the internal combustion engine," Honda F1 boss Yasuhisa Arai told ESPN, "but we know we still have the issue on the ERS, which is different."

Arai said the first track test of the new power unit in Russia went smoothly.

"It was the first time the new engine had ever run on the track and from the dyno we confirmed all the fundamental workings of the engine and are happy with the outcome. It is a good thing going forward."