F1: a Ferrari engineer gives his opinion on the Mercedes 2026 engine trick "they've found a clever solution".

As the controversy surrounding the Mercedes 2026 engine continues to rage in the paddock, a new element has shed new light on the debate. After official letters sent to the FIA, controversial regulatory validation and pressure maintained by Ferrari, Audi and HondaNow it's the voice of an in-house Ferrari engineer who's shedding a light that's as rare as it is invaluable. And against all odds, his verdict is clear: Mercedes' trick is legal. A statement that could well seal, at least temporarily, the fate of this technical battle even before the first Grand Prix of the 2026 season.

At the heart of Maranello

The information is revealed by Leo Turrini on his blog Profondo Rosso, through the testimony of a Scuderia engineer, voluntarily anonymized and nicknamed "Gola Profonda". A conscious choice, given the explosive nature of the subject. For several weeks now, Ferrari has been at the forefront of denouncing what it considers to be a dangerous interpretation of the 2026 engine regulations. Behind the scenes, however, the technical discourse appears far more nuanced. The engineer begins by pointing out an obvious fact often misunderstood in public debate: the compression ratio of an internal combustion engine is nothing more than the ratio between the maximum and minimum volume of the combustion chamber, measured when the piston passes from bottom dead center to top dead center. And, above all, this ratio can only be measured when the engine is cold, at room temperature. This is precisely where Mercedes found its window of opportunity.

Thermal expansion

According to this Ferrari engineer, Mercedes has designed its combustion chamber with materials capable of controlled expansion at high temperatures. When cold, during FIA testing, the engine complies strictly with the required 16:1 ratio. But under real operating conditions, the internal geometry evolves, increasing the maximum volume of the chamber to the equivalent of a ratio close to 18:1. In other words, the engine remains compliant where it is controlled... while becoming more efficient where it is used.

"They've come up with a clever solution", the engineer soberly sums up. A phrase that carries a lot of weight, especially when it comes from Maranello. He also stresses a fundamental point: measuring a compression ratio when hot is simply impossible with current regulatory tools. Mercedes has therefore simply exploited a structural constraint in the regulations, without ever formally violating them.

Ferrari lucid, but trapped by the calendar

Perhaps the most striking aspect of this testimony is what it reveals about Ferrari's real position. Unlike Mercedes, Ferrari's 067/6 and 067/7 engines, which will equip the Scuderia for the entire 2026 season, do not incorporate this solution. Neither for the first half of the championship, nor after the summer break. This choice is not the result of an oversight, but of a more conservative reading of the regulations, shared with Audi and Honda. An approach that seemed reasonable until the FIA officially validated Mercedes' interpretation. Now the facts are stark: if the German solution works as planned, the advantage could last the whole season. The figures quoted in the paddock confirm the scale of the problem. Around 10 to 15 extra horsepower, or almost three tenths per lap on certain configurations.

ADUO, Maranello's last hope

Ferrari's engineer is realistic about the situation. Reproducing such a solution during the season is virtually impossible without starting from scratch, with long and costly validation cycles. The only credible way of catching up is through the ADUO (Additional Development and Upgrade Opportunities) introduced by the FIA for 2026. This mechanism will enable engine manufacturers in difficulty to benefit from additional hours on the test bench, budgetary flexibility and, potentially, partial new homologation. Every six Grands Prix, the FIA will analyze the performance gaps between engines. Should Ferrari fall significantly behind, it could then obtain the regulatory means to attempt to close the gap.

Mercedes, still ahead of its time?

This latest episode is eerily reminiscent of the start of the hybrid era in 2014, when Mercedes took everyone by surprise with a conceptual lead that was irrecoverable in the short term. Ten years on, the scenario seems to be repeating itself. Even if validated in regulatory terms, the 2026 engine trick raises a broader question: that of the spirit of the regulations versus the letter. Ferrari knows this. In public, the Scuderia continues to keep up the pressure on the FIA. In private, the engineers recognize the reality: Mercedes has played with the rules... and won this round.