While the FIA has signed off on Mercedes’ 2026 engine, rival teams aren’t happy with how the private test was handled at their factory.
The debate around Mercedes’ 2026 engine, built for themselves and customer teams Alpine, McLaren and Williams, has been ongoing for months. Concerns first came to light in December when Ferrari, Audi and Honda raised questions about whether it met regulations.
Ferrari have asked the FIA to look into claims that Mercedes’ new V6 can push its combustion rate from the legal limit of 16:1 up to 18:1 during races – a threshold lowered from 18:1 under F1’s updated rules for 2026.
Red Bull have now added their weight to Ferrari’s side in the dispute, reportedly only after failing to replicate what Mercedes have done. Their awareness of the situation is said to have come from hiring engine staff away from Mercedes.
Rival F1 teams think the FIA tested Mercedes’ 2026 engine at the wrong temperature
Despite objections from Audi, Honda, Ferrari and Red Bull, the FIA has given Mercedes’ 2026 engine a clean bill of health. Even so, the matter isn’t settled just yet – it’s set to come up again at Wednesday’s F1 Commission meeting in Bahrain.
According to Motorsport.com, some in the paddock are still questioning how Mercedes’ engine managed to pass the FIA’s compression test. There’s even a suggestion that it may not have been tested under the correct conditions.
Reports say that while regulations require engines to be checked at ambient temperatures, stewards conducted their inspection after warming up the unit. It passed under those circumstances, but there’s doubt about whether that fully met testing protocols.
But rival teams argue that director Vincent Pereme didn’t go far enough with his tests. While he brought the engine up to 115°C before cooling it down to 75°C for dismantling, some feel those steps didn’t accurately reflect typical operating temperatures.
How Mercedes’ engine design stays within 2026 regulations
Mercedes have kept the FIA informed throughout the development of their engine, and the governing body has consistently given its approval. Still, other teams aren’t happy, believing the design could provide up to four tenths of a second advantage per lap.
The Silver Arrows are said to have created a second micro chamber within the cylinder head, measuring no more than 2cc. This chamber fills with air at room temperature to align with the 16:1 compression rate limit but becomes ineffective once the engine reaches operating temperatures.
Even though the FIA remains confident that Mercedes’ engine complies with the regulations, other teams plan to raise the issue again during Wednesday’s F1 Commission meeting in Bahrain. Reports suggest Ferrari are even developing a new testing method specifically for Mercedes’ power unit.
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