Honda F1 boss Yusuke Hasegawa has acknowledged that the manufacturer's change of engine concept last winter has been more difficult than expected.
Honda's poor reliability and performance earlier this season called its different approach in to question in addition to putting it painfully at odds with partner McLaren.
But despite the troubled campaign, Hasegawa believes Honda is on the right path as its recent progress appears to indicate.
"From the concept point of view, yes, we underestimated it," Hasegawa told Motorsport.com.
"Although it took a bit of time to stabilise, we understand it was a stage we had to overcome - it was very tough.
"We thought we had enough preparation time, which is why we started this year’s engine development in May, but one year is not enough.
"Theoretically speaking, we have already achieved some good steps. We are in the middle of our target but we need more steps to catch the top runners."
Progress and development is an incremental process, but Hasegawa admits that after introducing its latest Spec-3 power unit in Baku, Honda now needs to decide which components are likely to benefit from additional upgrades this year as its search for more power continues.
"We know the target, which other teams have already achieved," Hasegawa said.
"We know most of the teams are using the same concept of our engine but obviously we don’t know the exact solution, the exact design, the same level of performance we can achieve.
"But we know the direction and we know some elements to achieve that performance, but we still have not concluded what elements we have to introduce.
"[We are focusing] mainly the combustion but also every area, such as fuel consumption, auxiliary parts - everywhere we’re trying to find more horsepower."