Mercedes' F1 rivals might now vote down their own engine proposal, creating a complex and controversial situation in the sport. The engine compression ratio story, sparked by claims that Mercedes' new F1 2026 power unit exceeds the 16:1 ratio limit when hot, has taken an unexpected turn. The Power Unit Advisory Committee (PUAC) has proposed a 'cold and hot test' to be voted on by the five power unit manufacturers, but this may not get the required four manufacturer votes to progress. This is because some manufacturers were pushing for a 'hot-only' test, allowing them to exceed the 16:1 limit when cold and drop to the regulation limit when up to operating temperature. The proposed test would thwart this plan, as the 'compliant at all times' regulation would be used against those complaining. This leads to a bizarre situation where rival manufacturers could vote against their own initiative. Mercedes' Toto Wolff explained that the test needs to be compliant when cold and hot, ensuring fairness for all. The technical backdrop reveals that most power units lose compression ratio as they gain temperature, with a typical 16:1 cold engine dropping to around 15.2:1 in operation. The proposed 'hot test' involves stripping the cylinder heads, fitting measurement devices, and heating the engine to 130°C. This could allow Ferrari, Red Bull, Honda, and Audi to have more power, while reducing Mercedes' power. However, the cold and hot test being proposed would preclude this. At least four of the five manufacturers (plus FOM and the FIA) need to vote in favor of the proposal for it to progress. The power unit hardware specifications are locked in place after March 1 if no adjustment is made. This situation raises questions about the future of engine regulations and the potential impact on team performance. It remains to be seen how the manufacturers will vote and what the outcome will be for the sport.
