FORMULA 1 2026 ENGINE LOOPHOLE: IS MERCEDES SAFE?
A disagreement between Formula 1 engine manufacturers over the 2026 engine rules has raised fears that next season could be unbalanced before it even begins.
The argument centres on a new rule that limits engine compression ratio to 16:1. Mercedes and Red Bull are believed to have designed their engines so that they meet this limit when measured in the garage (as the rules specify), but exceed it slightly when the engine is running at full speed and temperature on track.
Their rivals argue this breaks the spirit, and possibly the letter, of the rules. They believe the compression ratio should never exceed 16:1 at any time, including while the car is racing.
Why this matters is performance. Simulations suggest that running closer to the old 18:1 compression ratio could be worth around 10 kW (about 13-15 horsepower), translating to roughly 0.3–0.4 seconds per lap. That’s a huge advantage in modern F1 and could decide championships.
The FIA currently measures compression only when the engine is cold and stationary, which matches how the rule is written. From that point of view, Mercedes and Red Bull argue they are fully legal and have simply designed better engines within the rules. The FIA has so far backed this interpretation.
The big concern for rivals is that engine designs are largely locked in for 2026 due to homologation rules. Major design changes are slow and expensive, meaning any team that got this wrong may not be able to fully catch up until 2027.
There is a partial safety net: if a manufacturer is clearly behind on performance during 2026, the FIA can allow extra development opportunities. But it’s unclear whether this would be enough to redesign engines to match the compression advantage quickly.
At this stage, everything is still theoretical. No engines have raced yet, and no one knows exactly how much advantage Mercedes and Red Bull really have. It may turn out to be decisive, or much smaller than feared.
What is certain is that the issue will dominate discussion early in 2026, and there’s a real possibility of protests at the opening races, especially in Australia.
The FIA has made it clear that, in its view, there is no confusion about the rules. What matters is that the compression ratio is checked at ambient temperature, as written in the regulations. If that process is followed, the FIA considers the engine legal and sees no need to get involved further.
Mercedes has been working closely with the FIA throughout the rule-making process, so it is not accused of trying to sneak anything past. The team was told its interpretation was correct and continued its engine design based on that.
Changing the rules now for 2026, for example by measuring compression when engines are hot, just because some manufacturers did not use this area of the rules would be unfair.
As per The Race, the FIA has said it could look at changes in the future, but that would most likely only happen for 2027 and would need to be clear and fair to everyone. One idea being discussed is to return to the old 18:1 limit or remove the compression limit entirely, so all teams know exactly where the line is.
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