F1 teams face mid-season FIA rule change

A mid-season F1 rule change could transform the 2026 campaign following an official statement from the FIA.

Mercedes' power unit and their controversial engine trick regarding their compression ratio, has bubbled away in the off-season and into Bahrain testing.

The team have discovered a clever loophole in the regulations which means that their compression ratio is at the allowed 16:1 at ambient temperature, but can then be increased to the previously allowed 18:1 when moving at higher temperatures, something that could allow an extra 15 brake horsepower.

Currently, the compression ratio can only be measured at ambient temperatures, but a recent meeting could change all of that.

Following a meeting of the Formula 1 Power Unit Advisory Committee, the FIA revealed that a proposal has been put forward which could see the ratios being measured both at ambient temperatures and at a representative operating temperature of 130 degrees Celsius.

Power unit manufacturers are due to vote on whether to introduce the rule or not and an outcome is expected to be announced 'within the next 10 days'.

F1 HEADLINES: Hamilton questioned as Ferrari take advantage of 2026 'loophole'

When would power unit changes come into play?

While a decision could be made in the coming days, compliance with the compression ratio limit at both ambient and higher temperatures does not come into force until much later in the season.

These changes would come into play from 1 August 2026, during the summer break and Zandvoort would be the first race weekend affected by the change.

This means that Mercedes could continue to run with their current engine for as many as 13 rounds, substantial time for them to garner a lead in the championship if the loophole does indeed present them with a significant advantage.

When does the 2026 F1 season start?

After the first round of pre-season tests in Bahrain took place between February 11 and 13, the second round continues this week between February 18 and February 20.

All 11 teams will then be back in action when the 2026 season starts in Melbourne for the Australian Grand Prix. The first race of the year takes place on March 8 at 3pm local time (AEDT), 4am GMT, and 11pm ET.

READ MORE: FIA announce official F1 vote over Mercedes compression ratio controversy

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