A new meeting between the FIA and the Formula 1 teams is scheduled for tomorrow to further address the controversial issue of the compression ratio used by the Mercedes power unit. At the center of the discussion is the potential advantage gained by the German manufacturer and whether “hot” checks on the compression ratio could be introduced earlier than initially planned.
Ferrari is determined not to lose what has increasingly become a political and technical battle against Mercedes. All power unit manufacturers are reportedly aligned against the German team regarding the interpretation of the compression ratio regulations. The FIA is now tasked with finding a clear and enforceable solution, particularly concerning the measurement of the compression ratio under operating temperature conditions. Tomorrow’s meeting could therefore prove decisive, with the possibility of anticipating the new rule.
On February 18, the F1 Commission met during pre-season testing in Bahrain to once again discuss the introduction of hot checks for the Mercedes compression ratio. The FIA’s official statement read: “In recent weeks and months, the FIA and the power unit manufacturers have collaboratively developed a methodology to quantify the variation of the compression ratio from ambient to operational conditions. Following validation of this approach, a proposal has been presented. From August 1, 2026, compliance with the compression ratio limit must be demonstrated not only under ambient conditions, but also at a representative operating temperature of 130°C.”
However, another meeting with the FIA is now set to take place, where a clearer decision regarding the alleged Mercedes trick could emerge. Ferrari is reportedly increasing the pressure, and new details are coming to light.
Mercedes not reaching 18:1? Could hot checks be anticipated by one month?
According to reports from AutoRacer.it, several engine manufacturers believe it is unlikely that Mercedes has truly reached a compression ratio of 18:1, the figure used in 2025, but rather a slightly lower value. Even so, that figure would still exceed the 16:1 compression ratio permitted under cold measurement conditions.
Such a configuration could be worth as much as 25 additional horsepower, which would represent a significant performance advantage for rivals already concerned about the competitive gap. Ferrari, Honda and Audi reportedly sent a letter to the FIA requesting clarification on the matter.
Based on information from the Italian outlet, manufacturers were close to signing off on revised regulations to resolve the issue at its root, avoiding potential legal disputes and breaking the current deadlock. The updated rules would aim to define clearer verification methods and eliminate any regulatory grey areas once and for all. Tomorrow’s meeting between the manufacturers is expected to provide further answers.
Meanwhile, Motorsport-Magazine reports that the introduction of the hot compression ratio rule could be brought forward to June 1, one month earlier than originally planned. That would reduce the period in which Mercedes could potentially benefit from the advantage. From 2027 onwards, cold checks on the compression ratio are expected to be completely abolished.
An engine manufacturer told AutoRacer.it that thermal expansion at operating temperature can lead to degradation in power units. Mercedes, however, is believed to have solved the issue “by maintaining a high power output parameter from the engine.” Initial rumors suggested a ratio of 18:1. If Mercedes were indeed able to achieve that figure, the performance gain could reach up to 50 horsepower.
This scenario also explains why Ferrari reportedly never considered adopting a similar solution for its own engine, instead choosing to pursue a different development path within the regulatory framework.
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