Mercedes’ rivals have succeeded in securing a rule change following a pre-season technical row over engine efficiency.
Audi, Ferrari, Red Bull and Honda had been pushing for a change within the regulation governing compression ratios on the idea they believed Mercedes had secured a bonus by means of intelligent use of supplies know-how.
Formula 1’s governing physique the FIA stated on Saturday {that a} change to the best way the compression ratio was measured could be launched on 1 June, with an additional revision for the 2027 season.
A press release stated the rule change had been accredited unanimously by all power-unit producers.
The compression ratio is a measurement of the cylinder displacement between the 2 extremes of the piston stroke. Typically, a rise will lead to extra energy.
Some estimates of the achieve Mercedes might be reaching have been as a lot as 0.3 seconds a lap, however Mercedes F1 boss Toto Wolff has stated it quantities to “a few horsepower – in England you would say a couple, which is more like two and three”.
The authentic rule said the ratio could be restricted to 16:1 within the new engine guidelines launched this yr – a change from 18:1 underneath the earlier rules – and this was measured at ambient temperature.
Mercedes’ rivals have been pushing for the compression ratio to be measured at working temperature.
The Mercedes engine has been measured by the FIA at each ambient and working temperature and complied with the restrict of 16:1 at all instances, senior F1 insiders have informed BBC Sport.
Compression ratios have a tendency to lower as an engine rises in temperature as a result of of thermal growth of the supplies concerned. The perception was Mercedes had discovered a more practical means to restrict this loss than different producers.
From 1 June, the compression ratio can be measured at 130C in addition to ambient temperature, and from subsequent yr solely at 130C.
That implies that from subsequent yr, producers can be in a position to have engines that exceed a compression ratio of 16:1 at ambient temperature, despite the fact that this discount from the earlier restrict was launched into the 2026 rules to make the principles extra interesting to new producers.
Audi and Ford each entered F1 as a result of they have been attracted by the brand new power-unit guidelines, which introduce a close to 50-50 cut up between inner combustion and electrical energy, and Honda reversed a call to stop.
A press release from the FIA stated: “A significant effort has been invested in finding a solution to the topic of compression ratio.
“The rules launched for 2026 characterize one of the most important modifications in latest reminiscence.
“All parties acknowledge that with the introduction of such significant regulatory changes, there are collective learnings to be taken from pre-season testing and the initial rounds of the 2026 championship.
“Further analysis and technical checks on power administration issues are ongoing.”
This last sentence is a reference to discussions over energy deployment and recovery.
Drivers have complained that because cars are energy starved this has led to unusual and counter-intuitive driving techniques – and there are numerous proposals to change the principles to make power administration simpler.
