Critical F1 deadline passes after FIA make late 2026 rule changes

F1's power unit suppliers have reached a critical deadline where they must supply the FIA with a full dossier of their power units. 

Power unit homologation has long been set for Sunday, March 1st, with recent late changes to the rules not having an impact on the deadline after the compression ratio row. 

To comply, each manufacturer must supply the FIA with its plans for its internal combustion engine, control electronics, exhausts, turbochargers, energy stores, and the MGU-K. F1's governing body will then examine the submissions before, if it is satisfied, granting its approval within 14 days. 

The dossier must be the same across all of a PUM's customer teams, with the fuel and lubricants also requiring to be submitted for checks.

Throughout the winter, it was revealed that Mercedes HPP had developed a trick to allow it to run a higher compression ratio limit than the 16:1 prescribed by the rules through a loophole, which stated it would only be measured at ambient temperatures. 

Therefore, in theory, it would be possible to run a higher compression ratio limit when the engine was hot on track, and not be in breach of the rules. 

Audi, Ferrari, Honda, and Red Bull Powertrains grouped together to try to force a change through F1's Power Unit Advisory Committee, with a recent E-vote confirming the change.

Originally, the new tests were set for introduction in August 2026, but on Saturday, the day before the power unit homologation deadline, the F1 technical regulations were updated to show that the compression ratio would be measured at ambient temperatures until "May 31st, 2026."

Article C5.4.3 then goes on to add that from June 1st to December 31st, the measuring will be at ambient temperatures and also 130 degrees Celsius. 

From January 1st, 2027, the compression ratio will be measured solely when the engine is hot.

This means any power unit manufacturer will have until after the Canadian GP to meet the first part of the new rules, before the full new measuring system comes into force ahead of the Monaco GP on the first weekend in June.