FIA shutdown ANOTHER F1 loophole after Red Bull and Mercedes controversy

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F1 2026

FIA shutdown ANOTHER F1 loophole after Red Bull and Mercedes controversy

Two manufactures were accused of exploiting the 2026 engine rules

Sheona Mountford F1 Journalist

Motorsport journalist working in F1 since 2024.

Monday 22 December 2025 17:56

The FIA have reportedly shutdown another avenue of exploiting the 2026 F1 rules after Red Bull and Mercedes were caught up in controversy.

Red Bull and Mercedes allegedly found a trick regarding the geometric compression ratio, which are changing within power units in 2026 from 18:1 currently down to 16:1.

The two teams were accused of uncovering a trick that would allow the geometric compression ratio to be 16:1 when the car is static, but move up to the previously allowed 18:1 ratio during the course of a lap - estimated to be worth 15bhp which would result in significantly better lap times.

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Rival F1 manufactures, Audi, Honda and Ferrari, have since urged F1's governing body to close any potential loophole in the interpretation of those rules.

Now on high alert, the FIA have recently discovered another loophole in the engine rules, this time regarding the fuel-flow meter.

What are the changes regarding the fuel-flow meter?

In 2026, the relevant limits will be imposed in a completely different way due to the switch to sustainable fuel, with the previous ceiling (a maximum mass flow of 100kg/h) being replaced fuel energy flow limit of 3000MJ/h.

Previously, two fuel-flow meters were used but will be replaced by a single standard unit, and will be fitted in all cars to deliver data that is available to both the teams and the FIA.

The FIA, however, want to block any opportunity for F1 teams to exploit these new rules, and have made some minor tweaks to the rules in recent weeks.

These 'tricks' revolve around teams potentially altering the temperature of the fuel-flow meter, which could benefit them either in changing the composition of the fuel that is being measured, or in altering the measurements that the device is taking.

In the original rule, there was a possible loophole in the word 'intentional' which read: "Any intentional heating or chilling of the fuel-flow meter is forbidden."

This wording has now been deleted and replaced with: "Any device, system, or procedure, the purpose of which is to change the temperature of the fuel-flow meter is forbidden."

While there is no evidence of any teams intending to exploit these rules, the removal of 'intentional' prevents any defence that manufacturers could change these temperatures unintentionally.

Red Bull Mercedes FIA