Formula 1 could be heading towards an early controversy in the 2026 season, with reports suggesting a possible protest at the Australian Grand Prix over an alleged power unit loophole.
According to Motorsport Magazin, Ferrari, Audi and Honda have raised concerns with the FIA about a method that Mercedes High Performance Powertrains and Red Bull Powertrains are believed to have identified under the new engine regulations.
From 2026, technical rules cap the geometric compression ratio of power units at 16:1. Rival manufacturers suspect Mercedes and Red Bull may have found a way to effectively restore this figure to around 18:1, the level permitted in the 2025 season.
The geometric compression ratio compares the volume of engine cylinders when pistons are at their lowest and highest points. A higher ratio allows more power to be generated. The alleged approach is thought to deliver up to 15bhp, which could translate into as much as 0.3s per lap at Melbourne’s Albert Park circuit.
Current FIA checks measure the compression ratio statically at ambient temperatures. While the precise mechanism has not been detailed, the theory is that higher operating temperatures could cause internal components to expand, increasing cylinder volume and effectively lifting the ratio during running.
The FIA has acknowledged awareness of the issue, Motorsport Magazin reported, and said it is continuously reviewing the matter to ensure fairness and regulatory clarity. Further discussions with power unit manufacturers are expected.
Any protest in Melbourne, whether upheld or dismissed, could have significant consequences. Adapting engines to operate at a higher ratio would require stronger pistons and connecting rods, while reverting to lower specifications could prove challenging, particularly for manufacturers supplying customer teams under existing regulations.
