F1's new three-engine limit is a "headache" for teams for the 2018 season, says Renault's Cyril Abiteboul.

But the Renault team boss has also not given up hope that the sport's powerbrokers could yet agree to a late change, despite FIA president Jean Todt saying before Christmas there was no going back for 2018.

While the calendar has increased back to 21 races, teams will be limited to one fewer penalty-free main engine, MGU-H and turbocharger than last year as part of a sliding scale imposed at the start of the current engine era in 2014 to control costs.

F1 2018: Race calendar and testing dates

Car launch date schedule

One engine now has to last for seven races - a situation Red Bull chief Christian Horner described as "barking mad" at the end of last season.

Abiteboul is confident Renault are prepared but believes the rule is unlikely to do F1 any favours amid fears drivers will be clobbered with grid penalties even earlier in the season.

"It's a headache but it's a known headache," he told Sky Sports News.

"We knew that it was coming so we have built our plans and strategy accordingly. Right now there is nothing to indicate that we can't stick to this plan.

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"Having said that, I still don't believe it's the right thing for Formula 1 and will still have another go [to change it] in the upcoming discussions with FIA and FOM and other teams because I don't think it really makes sense for anyone."

While three areas of the F1 power unit cannot be used more than three times in 2018, the limit has been reduced still further for three more elements - the MGU-K, energy store and control electronics. Each car only has a two-unit allocation for these three parts before penalties are imposed.

Grid penalties totalling more than 700 places were handed out across the 20-car field in 2017, the majority of which were racked up by Renault and Honda-engined cars.

To avoid farcical situations where drivers were receiving more penalty places than spots on the grid, demotions will now be capped at 15 places with any driver clocking up more than that simply sent to the back of the grid.

And what about the halo?

The biggest change for F1 2018 is the mandatory introduction of the halo head protection system onto cars after two years of on-track trials.

The flip-flop-shaped device which sits over the cockpit has regularly caused controversy with many fans and F1 personnel unimpressed with how it looks.

Asked how Renault were finding incorporating the halo onto their new RS18 car, which is launched on February 20, Abiteboul said: "We find it heavy and not very nice aesthetically but we have talked about that.

"The decision is made, it's necessary from a safety perspective and things need to evolve. I guess there will be more attempts to do that in a more refined manner but for the time being we are trying to integrate it in the best way possible."

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