Although the 2025 season has only just ended, interesting developments regarding technical concepts for next year are already happening behind the scenes.
The cars for next season, which will undergo major technical changes, have not yet completed a single kilometer on track, but the first “controversy” related to the new power units has already surfaced. The engines will see significant changes, at least in the hybrid part, while the internal combustion engine will remain largely unchanged. However, there is still one notable difference.
Specifically, the compression ratio in the cylinders is set to be reduced from 18:1 to 16:1. Mercedes is reportedly said to have come up with a clever solution that could allow them to effectively increase this compression ratio again, using material expansion. Under heat and pressure while running, the components would expand more, which would lead to an increase in cylinder volume and therefore a higher effective compression ratio.
Ferrari, Audi and Honda are said to have raised concerns about this solution, claiming that Red Bull Powertrains may also be using a similar concept. At first glance, it might not seem like a major difference, but this advantage could reportedly be worth up to 15 extra horsepower for Mercedes (or Red Bull). At Melbourne’s Albert Park, which hosts the opening race of the season, that could translate to as much as three tenths of a second per lap.
The FIA currently checks the compression ratio only statically, meaning not while the car is running, and in this case such an advantage would be impossible to measure during operation. It remains to be seen how the FIA will approach the situation, as this could represent a significant early-season advantage for Mercedes or Red Bull. Other teams simply no longer have enough time to redesign their engines before the start of the season, and might even struggle to implement such changes during the opening races, as it does not involve just the cylinder itself but all the associated components.
This certainly will not be the last time a team operates in the grey area of the regulations in search of an advantage over its rivals, especially now that the cars are undergoing major technical changes.