Why time is running out to make bigger F1 power unit changes for 2027

McLaren Formula 1 team boss Andrea Stella thinks further changes to the power unit regulations are still required, but the timelines involved are pushing any tweaks to 2028 rather than next year.

F1 recently agreed on a first set of refinements to improve the qualifying spectacle and reduce the extreme closing speeds seen over the first few races of the 2026 rules era. Last weekend's Miami Grand Prix was the first run under the tweaked ruleset and looked to bring modest improvements, with the jury still out on the exact impact of changes to the energy management until F1 heads to more energy-starved circuits later this spring.

While further sporting tweaks are not ruled out if necessary, there is a belief that more significant improvements will require changes to the actual hardware of the power unit, such as an increase in fuel flow which would squeeze more horsepower out of the internal combustion engine and alter the energy balance away from the electric engine, or a bigger battery which means cars don't run out of energy so quickly. A lower-impact move would be for the FIA to implement a minor reduction in downforce levels, as lower cornering speeds mean cars spend less energy.

However, provided F1 stakeholders come to an agreement through the relevant power unit governance structure, any moves to make structural changes to the power unit look extremely unlikely before 2028 at the earliest given the timelines involved, as an increase in fuel flow is not something the current engines are designed for. It would have an impact further downstream on the fuel tank and chassis, with several teams having already planned to stick to their current chassis for next season. 

Stella, whose team uses Mercedes customer engines, says an increase in fuel flow and a move to bigger batteries is required to fix the current formula, but acknowledged it would be difficult to push through for 2027.

"Hardware adjustments to the power unit in order to improve Formula 1 in general, I personally think are required," Stella said when asked for his view on the topic by Autosport.

Andrea Stella, McLaren

Photo by: Ryan Pierse / Getty Images

"They will have to do realistically with the fuel flow to increase the power from the internal combustion engine. I think they might have to do with harvesting more power than the power you actually deploy, because you spend much more time deploying electrical power, rather than harvesting it. This can be rebalanced by harvesting to a larger power than we do today. From 350kW, can we go to 400kW, can we go to 450kW? And then I think we just need bigger batteries.

"From the perspective of power unit manufacturers, I see this is difficult for 2027 because the implication for the battery size and the implication for coping with the higher fuel flow, they are normally a longer lead time than the time available to go into the 2027 season."

Stella is hoping for F1 stakeholders to finalise discussions ahead of the summer break to give manufacturers enough to put them in practice for the 2028 season. "I would urge that possibly this conversation needs to be finalised before the summer break to be in time to do it for 2028," he said.

"Definitely, I would hope that that's the case, because while we have done a good job as an F1 community of looking constantly at improving the exploitation of the engine with what's available, I think we can extract more out of these regulations, but this will need some hardware tweak."

Mercedes F1 chief Toto Wolff said he would not be opposed to minor tweaks to improve the spectacle, but argued the series is already in a good place right now.

"Whoever talks about changing engine regs in the short term should question his way of assessing Formula 1 at that stage," Wolff said after the Miami GP. "A spectacular race. Fight for the lead, fight in the midfield. And it's splendid.

Toto Wolff, Mercedes

Photo by: Sam Bagnall / Sutton Images via Getty Images

"Can we tweak it and optimise it in the mid-term? I think absolutely. We would never be against making the show even better. I'm thinking about Straight Mode. I think we need much more straightline speed with the straightline modes. We need to be courageous in doing that.

"Whether we could extract a bit more performance out of the ICE… Great, give us enough lead time so we can actually do it."

When asked when teams need to know what 2027's technical regulations will be, Alpine boss Steve Nielsen replied: "Now... More fuel means bigger a fuel tank, means a different chassis. And not every team will be planning to make a new chassis for next year, because with the budget cap you spend your money where the most performance is.

"It may not be that a new chassis is where the most performance is. But, of course, if your fuel tank's not big enough to take 10 or 20 extra litres, you'd have to do it and you'd have to know that. Very simple.

"We've seen a lot of regulation changes in the last few weeks. I hope it calms down a bit. But our ability to react will be stretched if we start getting major changes in the next few months, for next year."