A brewing controversy threatens to overshadow F1’s 2026 season before it even begins. Credible sources allege that two major manufacturers have discovered a clever workaround to compression ratio restrictions in the F1 2026 power units.
Sources speaking to The Race claim Mercedes and Red Bull have engineered their F1 2026 power units to circumvent new technical limitations by exploiting thermal expansion principles. This development could reshape the competitive order when racing resumes, with Mercedes supplying four teams and Red Bull powering two.
The technical trick
The controversy hinges on a straightforward concept: heat expands engine components. Officials measure compliance at ambient temperature, not during actual racing conditions, which creates the loophole. Teams must demonstrate their compression ratios fall within the mandated 16:0 limit, down from the previous 18:0 ceiling.
Insiders suggest certain manufacturers have designed intricate components that expand substantially at operating temperatures. When heat builds up on track, these parts push the piston closer to the cylinder’s peak than cold conditions allow, effectively increasing compression beyond what regulators measure in the garage.
Engineers know that higher compression ratios deliver improved fuel efficiency and additional power output, potentially gaining several tenths of a lap time.
Regulatory ambiguity
The FIA finds itself in a delicate position. Thermal expansion represents physics, not cheating in the traditional sense. Yet teams exploiting this gain a competitive advantage that may contradict the spirit of rules that aim to level the playing field.
Article C5.4.3 of the technical regulations has become a focal point. Manufacturers have spent months debating its interpretation, prompting officials to revise it repeatedly. In October, the FIA specified that teams would execute compression ratio procedures “at ambient temperature”. More recently, the governing body shifted responsibility, now requiring manufacturers to detail measurement methods per guidance document C042, with the caveat: “This procedure must be approved by the FIA technical department and included in the PU Manufacturer homologation dossier.”
An FIA spokesperson defended the current framework: “The regulations clearly define the maximum compression ratio and the method for measuring it, which is based on static conditions at ambient temperature. This procedure has remained unchanged despite the reduction in the permitted ratio for 2026.”
However, the spokesperson acknowledged the complexity. “It’s true that thermal expansion can influence dimensions at operating temperature, but the current rules do not currently require measurement under hot conditions.”
“That said, the topic has been and is still being discussed within technical forums with the PUMs [power unit manufacturers], as the new limit naturally raises questions about interpretation and compliance. The FIA continuously reviews such matters to ensure fairness and clarity, and if necessary, adjustments to the regulations or measurement procedures can be considered for the future.”
High stakes
The timing complicates matters considerably. Teams homologised their F1 2026 power units months ago, which makes fundamental changes extraordinarily difficult. Any ruling that requires internal modifications would force teams to undertake extensive redesign work they may not have time to complete before the Australian Grand Prix.
This creates a no-win scenario: either the FIA permits the practice and forces competitors to scramble for equivalent solutions, or officials ban it and potentially compromise the preparations of multiple teams that have already committed to their current specifications.
Rival manufacturers face a stark choice. They can accept the situation and attempt to develop similar systems for future seasons, or they can lodge formal protests when racing begins in Australia, potentially triggering a legal battle that could extend through the early rounds of the championship.
The controversy underscores a fundamental challenge in modern Formula 1: as engineers develop more sophisticated solutions for the F1 2026 power units, regulators struggle to write rules that anticipate every possible interpretation. What appears on paper as a straightforward compression ratio limit becomes, in practice, a complex negotiation between physics, engineering creativity, and regulatory intent.
Whether technical forums or courtroom arguments will resolve this dispute remains uncertain, but one thing stands clear. Tension extending well beyond the track will mark the start of the 2026 season.
