FIA announces clampdown on compression ratio tests from June 2026

Formula 1's governing body the FIA says the series' power unit manufacturers have unanimously approved changes to how engine compression ratios are measured, with revisions coming as early as 1 June.

The compression ratio of the V6 combustion engines, which measures how much the air-fuel mixture inside a cylinder can be compressed, has been reduced to 16:1 for this generation of power units - partly to help make building engines more accessible to newcomers like Audi.

But rival manufacturers, believed to be led by Audi, took issue with a clever way to comply with the 16:1 compression ratio in cold and static conditions, which is how it is measured by the FIA, while expanding it under hot, running conditions and gaining a significant advantage. Audi was joined by Honda and Ferrari in lobbying the FIA to address the issue before the start of the 2026 season next week in Australia, even if Mercedes had received reassurances its power units are fully legal.

F1's manufacturers disagreed over their interpretation of the 2026 power unit regulations

Following a series of discussions the FIA put up a compromise for an e-vote among the five power unit manufacturers, giving all parties 10 days to vote for the proposal. That solution is to start measuring the engine compression ratios both on hot and cold conditions from 1 June, and subsequently only measuring them in operating conditions at 130C from the 2027 season onwards. The FIA has now said all manufacturers have voted for the proposal, with the changes also ratified by the FIA World Motor Sport Council.

"A significant effort has been invested in finding a solution to the topic of the compression ratio," the FIA said in a statement on Saturday morning. "This parameter, which was one of the key fundamental targets of these regulations in order to attract newcomers to the sport, is limited in the regulations to 16:1, measured in cold conditions.

"The FIA has worked to find a compromise solution which determines that the compression ratio will be controlled in both hot and cold conditions from 1 June 2026, and subsequently only in the operating conditions (130deg C) from 2027 onwards."

Speaking exclusively to Motorsport.com, Red Bull team Laurent Mekies said his squad, which also produces its own power units for the first time, just wanted clarity on the matter before going into the new campaign.

“We’re asking for clarity. Tell us what we’re allowed to do, and the rest matters little: it’s essential to have a clear understanding of what is permitted, and then I believe every competitor should be free to reach the result by following the path they consider best. This applies not only to the power unit, but to everything," Mekies said.

The FIA also said it will continue evaluation data from pre-season testing and the first rounds of the season amid concerns over the draconian energy harvesting tactics drivers will have to use to optimise the new-for-2026 power units, which rely much more heavily on electric power than their predecessors.

"The regulations introduced for 2026 represent one of the biggest changes in recent memory," the statement continued. "All parties acknowledge that with the introduction of such significant regulatory changes, there are collective learnings to be taken from pre-season testing and the initial rounds of the 2026 championship. 

"Further evaluation and technical checks on energy management matters are ongoing."

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