LONDON — Formula 1’s governing body has reached a compromise with manufacturers that changes the way the compression ratio will be measured midway through this season and in 2027.
New engine rules set out a compression ratio of 16:1 — a measurement of how tightly the pistons squeeze the mixture of fuel and air before it ignites, and therefore how much power can be generated.
The regulations include a test to stop teams exceeding 16:1, but the checks happen at “ambient temperature.” Some rival teams have suggested the Mercedes team, which has Kimi Antonelli and George Russell as its drivers, found a way for components to behave differently when they heat up during use and beat the test.
Mercedes, which says its engine is completely legal, also supplies three other teams: McLaren — which has won the constructors’ championship the past two years — Alpine and Williams.
The compromise announced Saturday means the compression ratio will be controlled in both hot and cold conditions from June 1 and only when hot from the 2027 season thereafter.
There are seven F1 races before the June 1 test, beginning with the season-opening Australian Grand Prix on March 8 at Melbourne’s Albert Park.
“The regulations introduced for 2026 represent one of the biggest changes in recent memory,” FIA, the sanctioning body for the international open-wheel circuit, said in a released statement. “All parties acknowledge that with the introduction of such significant regulatory changes, there are collective learnings to be taken from pre-season testing and the initial rounds of the 2026 championship.
“Further evaluation and technical checks on energy management matters are ongoing.”