Christian Horner Pushes Back Against ‘Cheating’ Claims in Explosive F1 Engine Debate
Christian Horner has issued a firm response to accusations that Red Bull and Mercedes are exploiting a loophole in Formula 1’s new power unit regulations, amid growing controversy surrounding engine compression ratios ahead of the 2026 season.
The former Red Bull team principal, who played a key role in establishing Red Bull Powertrains (RBPT) before his departure from the team in mid-2025, has defended both RBPT and Mercedes High Performance Powertrains (HPP) following claims that the two manufacturers are “cheating like wildcats” with their latest engine designs.
During the winter break, reports surfaced suggesting that RBPT and Mercedes have developed power units capable of operating with a compression ratio as high as 18:1 — significantly above the 16:1 limit outlined in the FIA’s regulations. The alleged advantage stems not from outright rule-breaking, but from how and when the compression ratio is measured.
Under the current regulatory framework, compression ratios are assessed at ambient temperatures in the pit lane. However, the FIA currently lacks the technology to measure this parameter while a car is running on track at full operating temperatures. This has led to speculation that some manufacturers may be using heat-responsive materials within their engines, allowing the cylinder volume to subtly expand when hot — effectively increasing the compression ratio during racing conditions.
If such a system is being employed, the performance gains could be significant. Estimates suggest an engine running at an effective 18:1 compression ratio could deliver an advantage of roughly three tenths of a second per lap at Melbourne’s Albert Park Circuit. Over the course of the 58-lap Australian Grand Prix, that margin could translate into a race-winning advantage of more than 17 seconds.
The issue has triggered high-level discussions between the FIA and all power unit suppliers. Despite the concerns, FIA single-seater director Nikolas Tombazis has expressed confidence that a technical solution will be agreed upon. Crucially, rival manufacturers Audi, Ferrari, and Honda have indicated they do not intend to lodge formal protests, suggesting a collective willingness to resolve the matter through regulation rather than litigation.
Speaking publicly about the controversy for the first time, Horner dismissed the accusations while appearing on Australia’s Today programme ahead of a scheduled speaking tour.
“That’s a pretty strong accusation,” Horner said when confronted with the claims. “Formula 1 has always been about pushing the limits. It’s about interpretation of the rules — that’s how the sport has always operated.”
Horner emphasized that innovation and aggressive engineering are not only legal but essential to success in Formula 1. According to him, teams that adopt a cautious approach rarely find themselves at the front of the grid.
“If you’re conservative, you’re not winning races,” he explained. “To be competitive in this sport, you have to challenge boundaries and explore every opportunity within the regulations.”
He also highlighted the calibre of talent working within modern F1 power unit projects, noting that the sport attracts some of the most advanced engineering minds in the world.
“You’ve got incredibly bright engineers reading every word of those rules and asking one question: how do we extract the maximum performance while staying compliant?” Horner added.
As the 2026 regulations draw closer, the compression ratio debate has become another reminder of Formula 1’s perpetual tension between innovation and enforcement. While the FIA works to refine its measurement methods, the controversy underscores how small technical details can carry massive competitive implications — and why the battle off the track is often just as intense as the one on it.
For now, Red Bull and Mercedes remain confident they are operating within the rules, even as scrutiny intensifies and the sport prepares for one of its biggest technical resets in decades.
