The FIA ​​clarifies engine compression ratio control

The rivals of Mercedes Benz called for more clarity on the compression ratio; they finally got it. Following a meeting held in Bahrain on the sidelines of pre-season testing, it was decided that an electronic vote would be conducted, consulting the five engine manufacturers (Mercedes, Classic Ferrari for sale, Red BullAudi and Honda), as well as the FIA ​​and FOM. While six out of seven votes were required to validate a regulatory change, the proposal was ultimately adopted unanimously.

Thus, from June 1, 2026, engine compression ratios will be measured both when cold, as before, and also at 130°C, under operating conditions. This is not exactly what rival engine manufacturers had requested, as they advocated for testing only when hot. Indeed, compression ratios are normally higher when cold than when hot; testing only when hot would therefore have allowed other manufacturers to exceed the permitted ratio of 16:1 when cold in order to fall below it when hot.

Today, with this dual control system, they will need to maintain a 16:1 compression ratio when cold, and therefore lower when hot. At Mercedes, the opposite is true: the Germans have developed an engine capable of increasing its compression ratio when hot thanks to material deformation caused by heat. This clever trick gives them an advantage over the competition, but one that remains difficult to quantify. While the Brackley-based team has always downplayed the true significance of their discovery in terms of performance gains, their rivals expect it to provide an advantage of 10 to 15 horsepower, translating to two or three tenths of a second per lap depending on the circuit.

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End of the two mandatory stops in Monaco

Finally, a compromise was reached: from June 1st, a dual testing procedure will be implemented, both hot and cold, while for the 2027 season, it will be a hot-only test. This option appears to have convinced all stakeholders, as the regulation change was adopted unanimously.

In its press release, the FIA ​​also indicates that it is currently considering the energy management requirements of the 2026 Formula 1 cars with their 50% electric motors. "An evaluation is forthcoming" and "technical checks" are underway. This should help alleviate team concerns about the cars' ability to generate energy and recharge batteries on circuits with few braking zones, such as Albert Park in Melbourne (Australia), and especially the street circuit in Jeddah (Saudi Arabia), which will host the first and fifth rounds of the season, respectively.

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In addition, two other regulatory changes were adopted: the extension of Q3 from 12 to 13 minutes and the removal of the rule of two mandatory pit stops in Monaco, introduced in 2025 to promote the spectacle, but whose results were inconclusive.