Ferrari and Red Bull teams doubt the legality of the Mercedes engine. The German team has improved the performance of their engine since the Grand Prix of Great Britain, and their rivals believe that they know what ‘trick’ Mercedes used.
Red Bull went a step further and sent an inquiry to the FIA regarding the legality of the Mercedes engine, while some sources claim that it was a protest. Red Bull since the British GP has its doubts about the Mercedes engine, which in the acceleration phase began to make a difference compared to Honda.
Since that race, the relationship between Honda and Mercedes has changed in favor of the Silver Arrows. In previous races, Red Bull had a significant advantage over Mercedes in all parts that run at full gas, but the situation has changed since Silverstone.
Mercedes explained this with different wing settings, and they claimed that their engine had the same performance since the beginning of the season and that nothing had changed in the drive unit. But Red Bull has a theory, and Ferrari is close to the whole thing.
The Mercedes engine has the same maximum power, but the power is distributed differently. According to the German Auto Motor und Sport, Red Bull and Ferrari allegedly already know that Mercedes is 'gaining' advantage at the beginning of the route in the acceleration phase.
The suspicion arose after analyzing GPS data which showed that Mercedes creates a huge advantage when accelerating from slow corners.
Allegedly, according to Red Bull and Ferrari, Mercedes has found a ‘trick’ that allows them to cool the air entering the engine, in the acceleration phase, which gives them a significant ‘jump’ in engine power at the moment.
The air that enters the engine is usually cooled from 100 degrees to the ambient temperature, but the rules allow some freedom. The cooled air entering the engine must not be 10 degrees below the outside temperature. Since cold air is denser than warm air, this proportionally means that it can burn more fuel, which means that the engine produces more power.
According to the theory of Red Bull and Ferrari, Mercedes manages to separate cold air from warm air for some time, directing the air between the radiator and the plenum (part of the airflow structure on the car), giving them up to 20 hp more in the acceleration phase.
Later the compressor only pushes warmer air and that advantage disappears. This trick is legal, but now the question is where are the sensors in the plenum that measure air temperature, because only certain temperatures are allowed and whether Mercedes has found a way to bypass those sensors.
Red Bull has its doubts and believes that the sensor measures at a point that ensures that the temperature where the air ‘collects’ is always above the required limit. Red Bull sent an official inquiry to the FIA, and some sources, according to AMuS, claim that this is also a complaint / protest.
In any case, this issue is expected to be resolved within a maximum of 2-3 races, and the FIA should respond by clarifying the rules or publishing a technical directive that will define what is legal and what is not.