F1 set for critical vote over major rule change

Formula 1 is set for a critical vote over changing the rules mid-season regarding the measuring of engine compression ratio. 

Over the winter, it was revealed that Mercedes HPP had developed an engine, which, when running hot, could produce a compression ratio of 18:1, exceeding the limit of 16:1.

The current rules state that the measurement of the compression ratio is done at ambient temperature, which the Mercedes unit would pass, but through the use of heat-expanding metals, could, in theory, increase to 18:1 whilst on track. It would be worth about 0.3s per lap around Australia's Albert Park. 

On Wednesday, at the second Bahrain test, a meeting of the Power Unit Advisory Committee (PUAC) was held - a body which features Mercedes HPP, Red Bull Powertrains, Ferrari, Audi, and Honda, as well as the FIA and Formula One Management (FOM).

A change of the regulations to measure the compression ratio whilst the engine is hot would require a supermajority of four teams, plus both the FIA and FOM. 

With RBPT, Ferrari, Audi, and Honda pushing for the change and Mercedes against, the final votes would be with the FIA and FOM, neither of which have declared theirstance publicly.

At the meeting of the PUAC, a proposal was submitted whereby, from August 1st, 2026, compliance with the compression ratio regulations must be demonstrated not only at ambient temperatures, but also "at a representative operating temperature of 130°C."

The vote has been submitted to the PUMs, with an outcome expected within the next 10 days. 

Any amendment to F1's technical regulations would require formal ratification from the World Motor Sport Council (WMSC).

Earlier in the day, Red Bull boss Laurent Mekies observed that his team simply wanted "clarity" over the course, one way or the other.