The FIA has adjusted the regulations for 2026 following alleged engine tricks by Mercedes. The German team could reportedly increase the compression ratio through thermal expansion. This effect only occurs on the track, where the power unit becomes much hotter than during the FIA’s static tests. However, the motorsport federation announced on Saturday that from June 1, the compression ratio will also be measured at temperatures up to 130 degrees Celsius.
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In the run-up to the new season, there was already much discussion surrounding Mercedes’ compression ratio. According to rivals, the Silver Arrows have found a clever solution where engine components expand at higher temperatures. Because the compression ratio has so far only been measured under static conditions – at ambient temperature – these components formally complied with all FIA checks. However, rival teams raised the alarm and lobbied for adjustments in recent weeks.
New tests from June 1
To settle the discussion, the FIA confirmed that compression ratios must henceforth also be measured at 130 degrees Celsius, in addition to the traditional checks at lower temperatures. Originally, these new measurements were not set to take effect until early August, following approval by the F1 Commission, but that schedule has been brought forward. The revised engine inspection rules will now come into effect as early as June 1. This means that Mercedes’ alleged advantage may still hold for the first seven races of the season.
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Although Mercedes downplays the importance of the issue, rival manufacturers point to a substantial performance advantage. Experts also emphasize that a higher compression ratio can make a significant difference on certain circuits. Reportedly, to prevent a recurrence of this engine discussion, the FIA intends to measure compression ratios exclusively at high temperatures from 2027 onwards.
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View the 2026 F1 calendar here
