Let’s clarify the numbers: the current Formula 1 regulations allow an internal combustion engine compression ratio of 16:1 measured at ambient temperature. All power units checked in Australia were compliant with the 2026 technical regulations.
However, a heated controversy has been sparked by some F1 power unit manufacturers claiming that Mercedes, thanks to the introduction of a pre-chamber in the cylinder head, can reach 18:1 when hot, which is the value that was permitted until last year. There is no proof that the Brixworth unit can reach that limit, although the rumour has been fuelled by someone familiar with the project who moved to another team and “leaked” the concept. It is, however, accepted that it exceeds the 16:1 compression ratio.
