The FIA have hastily arranged a meeting of the Formula One powertrain manufacturers for Thursday January 22nd. This follows complaints formally made to the sport’s governing body that Red Bull and Mercedes may have designed their power units with clever heat expanding components.
Within the all new 2026 technical regulations there is a requirement that each power unit’s internal combustion engine must have a compression ratio which does not exceed 16.1, however suspicions have surfaced that Red Bull and Mercedes are delivering a higher rate due to components which expand when hot.
The FIA’s test for the rate of compression is delivered with the car stationary and at ambient temperature which of course would not account for any changes in the compression rate when the car is operating at extreme temperatures when on track.
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Audi’s technical director, James Key – speaking at the Autosport business forum in London, has insisted his team will not accept a compromise which allows Mercedes and Red Bull to continue with their design, although the FIA restated its position regarding the way the compression checks will be performed.
“We have to, as we do, trust the FIA with making the right decisions here,” he said at the Audi team’s launch this week. “It’s new regs. You’ve got to have a level playing field. If someone came up with a clever diffuser and you said it’s not the right thing to do, no one else can have it, but you can have it for the rest of the year. It doesn’t make sense. We’d never accept that.”
Key’s reference to the double diffuser relates back to the F1 2009 season when Williams, Brawn and Toyota arrived pre-season with a clever double diffuser which exploited a grey area in the FIA’s chassis specifications.
This created a furore in the paddock with McLaren and Ferrari arguing to continue to allow the double diffuser was a politically motivated decision to hurt the chances of the Scuderia and the Woking based McLaren team. Yet the double diffuser remained and Adrian Newey at Red Bull set about designing a version of the double diffuser which saw the team roar back into contention later in the season.
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Yet despite this and many other precedents where gray areas in the specifications have continued to be allowed, James Key argues the FIA must take control of the situation and quickly. “I think if it’s sort of bypassing the intent of the regulations, then it has to be in some way controlled,” said Key.
“So we trust the FIA to do that, because no one wants to sit a season out if you’ve got a blatant advantage that you can do nothing with in a homologated power unit. So I think for us, hopefully, the FIA will make the right decisions,” concluded the Audi tech guru.
Yet the FIA have indicated that any manufacturer whose power unit is significantly underpowered, will after the first six race weekends be allowed to break the homologation rules and introduce modifications which seek to improve the performance of the PU.
The problem is that powertrains are far more complicated to modify than is a chassis and its related aerodynamic components. Whilst Mercedes have refused to comment on their rivals accusations, Red Bull Powertrains technical director, Ben Hodgekinson has addressed the issue suggesting there’s a lot of ‘noise’ going on with very little substance behind it.
Red Bull say rivals complaints are just ‘noise’
“I think there’s some nervousness from various power unit manufacturers that there might be some clever engineering going on in some teams,” said Hodgkinson at the team’s season launch in Detroit. “I’m not quite sure how much of it to listen to, to be honest. I’ve been doing this a very long time, and it’s almost just noise. You just have to play your own race really.
“I know what we’re doing, and I’m confident that what we’re doing is legal. Of course, we’ve taken it right to the very limit of what the regulations allow. I’d be surprised if everyone hasn’t done that. My honest feeling is that it’s a lot of noise about nothing. I expect everyone’s going to be sitting at 16 [the maximum compression rate allowed], that’s what I really expect.”
As happened in 2009, the FIA may well refuse to address the complaints of Audi and Honda in particular, instead allowing the manufacturers to develop their own malleable components which improve the compression rate when at temperature. The problem in modern F1 for the manufacturers is the lead times required to modify elements of their power units. From conception to delivering the component may well be a 12 week process as Hodgekinson reveals, then this would be followed by another 12 weeks of extensive bench testing.
To then modify the entire pool of PU’s for the likes of Ferrari – who are supplying Cadillac and Haas F1 – may then take another 12 weeks suggests the Red Bull Powertrains technical director. Lead times for Audi and Honda would be less given they are merely supplying two cars each with a power unit.
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Red Bull are believed to have learned of the Mercedes trick to increase the compression ratio’s when their cars are running hot, having signed an engineer from Brixworth in 2025. Yet it is thought they have not had the time to fully explore the benefits of the loophole and may be 2-3 months behind where Mercedes are presently at.
At the meeting tomorrow there is little expectation the FIA have a solution to the problem, given measuring the compression ratio’s on a live car on track is not the work of a moment. The simplest solution will be for the FIA to once again restate how their compression tests will be run, allowing the manufacturers to make of this what they wish.
Forcing Mercedes and Red Bull to re-engineer such critical aspects of their power units so late in the day is improbable, and as in 2009 the starting gun for the race to catch up may well be fired before the first of the pre-season tests beginning next week in Barcelona.
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On Tuesday, McLaren Racing officially announced a major new partnership with PUMA, the globally renowned German sportswear company. The collaboration, the subject of speculation since May 2025, will see PUMA become the British team’s new official equipment partner, replacing Castore. The agreement extends to several of the “Papayas’” divisions, including Formula 1, IndyCar, the World Endurance Championship (WEC), the sim racing team and the F1 Academy team.
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A.J. Hunt is Senior Editor at TJ13, where Andrew oversees editorial standards and contributes to the site’s Formula 1 coverage. A career journalist with experience in both print and digital sports media, Andrew trained in investigative journalism and has written for a range of European sports outlets.
At TJ13, Andrew plays a central role in shaping the site’s output, working across breaking news, analysis, and long-form features. Andrew’s responsibilities include fact-checking, refining editorial structure, and ensuring consistency in reporting across a fast-moving news cycle.
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