Honda doesn’t believe it will have a clear understanding of how much it has improved compared to rival manufacturers with its latest specification of power unit until after the Singapore Grand Prix.

The Japanese manufacturer introduced Spec 4 at the Belgian Grand Prix, with Alexander Albon and Daniil Kvyat testing the upgrade at Spa-Francorchamps. In Italy, Max Verstappen and Pierre Gasly also took the new power unit, but given the specific characteristics of Monza, Honda’s F1 technical director Toyoharu Tanabe says a circuit like Singapore is needed to give a better picture of any gains.

“From our data it worked well,” Tanabe told RACER. “But when you talk about the competitiveness compared to the others, it’s a little bit more difficult. Monza-spec aero is special, and the tow effect there is huge, so we need more time to analyze everything.

“I’d like to have the Singapore data with maximum downforce, so we can get more data and then we will have a more clear idea of what our position is. But other cars also improved a lot during the past two weekends. It’s difficult.”

Tanabe admits it was also challenging to gauge performance in Italy based on the power unit penalties both Red Bull and Toro Rosso took, while Kvyat retired from the race and Albon was compromised in qualifying.

“In Monza we had a difficult day. Two cars had a penalty because of the power unit change — that makes our race difficult. All four cars used Spec 4 and it ran generally OK during the weekend.

“On Kvyat’s car we are investigating the cause of the oil leakage — at the end of the race when he cut the engine the engine data was showing normal, so that’s OK. So we could get data … So far I’d say not good but not too bad.”