Formula 1's power unit manufacturers are preparing to vote on a proposal for additional tests to measure engine compression ratios under operating conditions. The change, aimed at addressing concerns over a potential loophole in the 2026 regulations, would require compliance checks at 130 degrees Celsius starting from August 1, 2026. The vote, submitted via email, is expected to conclude within 10 days.
The 2026 Formula 1 power unit regulations limit the engine compression ratio to 16:1, a reduction from the previous 18:1, with measurements traditionally taken at ambient temperature when the engine is not running. This method does not account for material expansion under heat during on-track operation, prompting concerns among rival manufacturers, reportedly led by Audi, that Mercedes could achieve a higher effective ratio closer to 18:1, potentially gaining a significant horsepower advantage.
Mercedes supplies engines to its own team, as well as McLaren, Williams, and Alpine. Rivals had pushed for changes before the season starts in Australia next month, but a compromise proposes introducing the extra test over the summer break. The Power Unit Advisory Committee, which includes Mercedes, Ferrari, Audi, Red Bull Ford, and Honda, along with the FIA and Formula One Management (FOM), will vote on the matter. Approval requires a supermajority: four manufacturers plus the FIA and FOM.
"Over recent weeks and months, the FIA and the Power Unit Manufacturers have collaboratively developed a methodology to quantify how the compression ratio changes from ambient to operating conditions," the FIA stated. "Following validation of this approach, a proposal has been submitted whereby, from 1 August 2026, compliance with the compression ratio limit must be demonstrated not only at ambient conditions, but also at a representative operating temperature of 130C."
Mercedes team principal Toto Wolff has insisted the engine is legal and approved by the FIA. Williams principal James Vowles downplayed the issue, saying, "I think there's probably a misunderstanding of just how significant it is... For me it's just noise frankly, it will go away probably over the next 48 hours is my guess."
Red Bull principal Laurent Mekies emphasized the need for clarity: "We don't think it's noise, we think we must have clarity... We are not stressed if it goes left or if it goes right, but we must have clarity on what we can and what we cannot do."
Ferrari principal Fred Vasseur added that the focus is on clear regulations rather than protests. If passed, the change would allow Mercedes-powered teams the first 13 races of the 24-race season under current rules. The FIA aims to resolve the matter before the season begins to avoid spillover from this technical controversy.
