Honda insists they face no serious problems with their engine and will only make small changes after testing.

The Japanese manufacturer enjoyed their most productive Formula 1 pre-season since returning in 2015 as both Red Bull and Toro Rosso ran flawlessly from a power unit perspective over the eight days.

Despite that, F1 technical director Toyoharu Tanabe confirmed the situation was not perfect ahead of the first race.

“We don’t have a serious problem with the current installation, but we found some issues because of the tight packaging,” he told Autosport, referring to the very narrow rear-end on both Red Bull cars.

“The shape was a little bit too aggressive, so we need to make it a little bit different. It’s not a big concern.”

Also Read:

• Max Verstappen praises Honda, doesn't rule out Australian GP win
• Honda: No extra pressure supplying Red Bull as target remains the same

While both Red Bull and Toro Rosso have heaped praise on their engine supplier, Tanabe won't accept it until they close the gap to Mercedes and Ferrari.

“[I'm] never happy, actually!" he said of the improvements. “Of course we have a target and a target through the year as well.

“We are not so confident with the current achievement [as there is] still a lot of areas we need to work on to catch up to the top competitors.”