Christian Horner has offered a strong defence to Red Bull and Mercedes over a claim that both are "cheating like wildcats" with their alleged engine compression ratio trick.
Over the winter, reports emerged that Red Bull Powertrains (RBPT) and Mercedes High Performance Powertrains (HPP) had developed a power unit for the new regulations, which could allow them to run with a compression ratio of 18:1, exceeding the permitted 16:1 in the regulations.
Currently, the ratio is measured at ambient temperature in the pit-lane, with the technology to measure it whilst a car is on-track unavailable, meaning, in theory, a team could use heat-expanding metals in its power unit design to allow the cylinder volume to increase, thus producing more power.
It is believed that any team running an engine capable of producing a compression ratio of 18:1 could enjoy an advantage of around 0.3s per lap at Albert Park in Australia, or 17.4s in race time across the 58 laps.
Meetings have taken place between the FIA and the power unit manufacturers to try to find a solution regarding the measurement of the compression ratio, with FIA single-seater director Nikolas Tombazis confident that a solution will be found, and a protest will not be launched by either Audi, Ferrari, or Honda-powered teams.
Horner, who set up RBPT before his dismissal from Red Bull in July 2025, has spoken about the topic for the first time and strongly defended both RBPT and HPP.
"That's a big statement," Horner began when the claim of Mercedes HPP and Red Bull RBPT "cheating like wildcats" was put to him on Australia's Today programme ahead of his speaking tour down under.
"Formula 1 is about pushing the boundaries. It’s about how you interpret regulations. [It] always has been and always will be.
"Teams that are the most conservative are the teams that are never at the front of the grid; you’ve got to be pushing the envelope.
"Of course, it’s all about how you interpret regulations and engineers, some of the brightest engineers on the planet, will be looking at those regulations and thinking: 'Okay, how can I maximise performance?'"
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