Just a few weeks before the first official appearance of the new cars at the Circuit de Catalunya, where they will be tested for the first time, the world of Formula 1 is shaken by the first major technical controversy related to the rules for 2026. At the center of the possible scandal is the new technical regulation, article C5.4.3 of which mandates the reduction of the geometric compression ratio of 1.6-liter V6 engines from the current 18:1 to a maximum of 16:1. This change was introduced with the aim of reducing peak performance and promoting more efficient fuel combustion.
An engineering trick
However, in recent days there have been some doubts that some engine manufacturers have found a “grey area” in the way this rule is checked. The rulebook requires that the compression ratio compliance check be carried out at “ambient temperature”. Sources state that Mercedes and Red Bull Powertrains allegedly designed their engines to meet the 16.1 compression ratio limit when cold, but then managed to exploit the vagueness of the regulations (which, we know, F1 engineers are masters at). Unofficially, the compression ratio is mechanically increased back towards the 18:1 level once the engine is warmed up and running – where the power generated is all that matters.
Rival engine manufacturers Honda, Ferrari and Audi have officially requested clarification from the FIA, believing that such a solution violates the spirit of the rules. From this it can be concluded that their engineers did not think of circumventing the rule book in a similar way. Since Article C1.5 mandates that cars must comply with the rules “at all times during competition”, the argument of rivals is that driving with an effective ratio above 16:1 is illegal, regardless of the results of the static cold test. Increasing the compression ratio brings significant benefits. It is estimated that returning to the 18:1 ratio can bring a gain of about 10 kW, or approximately 13 horsepower, with better fuel efficiency.
The FIA faces a dilemma
This situation puts the FIA in an awkward position just before the start of the new season, but also of the new technical era of Formula 1. They confirmed that the topic is a subject of discussion and that it continuously reviews such issues to ensure fairness. They admitted that the new limit naturally raises questions about interpretation and did not rule out the possibility of changing the measurement procedures in the future to close possible loopholes in the rules. They are, if all the unofficial information is correct, facing an awkward choice: either they will allow the trick and thus provide an undoubtedly large power advantage for teams using “hairstyled” engines, or they will ban it and enter into a dispute with almost half of the grid.
The stakes are, therefore, extremely high because the drive units for 2026 have already been approved or are in the final stages of preparation. If the FIA rules against the current interpretation reportedly used by Mercedes and Red Bull, those teams could be forced to make urgent mechanical modifications to permanently reduce compression. Engineers warn that such a forced return to the actual ratio of 16:1 would result in a direct loss of performance compared to current simulations, which could significantly affect the balance of power at the start of the season.
For context, let’s add the information that two Red Bull teams (Red Bull and Racing Bulls) use the engine of their company Red Bull Powertrains, while Mercedes engines for 2026 are planned to be used, apart from their factory team, by McLaren, Alpine and Williams. Of course, Ferrari also has its engines, which will supply them to the Haas and Cadillac teams. Aston Martin will exclusively use Honda engines, and Audi will use ones from its own development.