Why both sides have a case in F1's engine row

In the build-up to the 2026 Formula 1 season, aside from ‘energy management’, two other words have dominated paddock conversations so far: compression ratio. It was always to be expected that the overhaul of the technical regulations would spark debate – that is simply the nature of the game. F1 is a kind of mini-cosmos in which everything, down to the bone, is highly political.

The FIA tries to draft the regulations as tightly as possible, but as Williams boss James Vowles put it – slightly tongue-in-cheek – on Friday: “There's 20 odd people trying to fight against 10,000 out there on the grid.” And those 10,000 bright minds are relentless in uncovering loopholes – and exploiting them to the fullest.

It is entirely possible that more hidden traps will emerge in the coming months, but for now controversy centres on the compression ratio. For anyone who has been living under a rock in recent weeks, or who has only just awoken from their F1 hibernation ahead of the Bahrain test, it is worth briefly explaining what the compression ratio actually is – and why it has become such a talking point.

Put simply, it is the ratio between the volume of the cylinder when the piston is at the bottom of its stroke and the volume when the piston is at the top. Under the previous regulations that ratio was 18:1, but in the new 2026 rules it has been reduced to 16:1 – partly to make the formula more accessible for newcomers and easier to manage with fully sustainable fuels.

So far, so good. The issue only became contentious when rivals got wind of the fact that Mercedes may be able to meet the 16:1 limit during static tests, but achieve a higher ratio when the engine is running. Audi, Ferrari and Honda jointly sent a letter to the FIA, with Mercedes lead Toto Wolff referring in Bahrain to “secret meetings” and “secret letters”. Et voila – game on.

What is Mercedes doing and how big is the advantage?

Breaking it down further, the first question is how manufacturers can achieve a higher compression ratio while running than during static testing. It should be noted that nobody knows the exact values Mercedes reaches at operating temperatures, nor whether it fully hits the previous 18:1 figure or lands somewhere between the two.

Wolff is adamant that Mercedes' power unit is legal

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In the most favourable estimates from rivals, the advantage is said to be between 10 and 13 horsepower. Wolff, however, dismissed those figures and effectively removed the leading ‘1’: “It’s just a few horsepower. In England you would say a couple, which is more like two and three.”

The most widely discussed explanation in recent weeks concerns thermal expansion of materials. With equal cylinder capacity, a smaller combustion chamber results in a higher compression ratio. In that respect, particular attention has been paid to the material used for the piston. Yet that is far more complex than it sounds, given that 3D printing techniques with multiple layered materials are involved nowadays. And that, in turn, makes copying it easier said than done.

Another theory that has surfaced involves a mini combustion chamber connected via a small channel that, under high pressure while running, becomes blocked – effectively reducing the total volume compared to static tests.

Both sides genuinely have grounds to argue their case and that is precisely what makes this issue so complex and so fascinating

No right or wrong? Why both sides have a case

Regardless of the exact technical mechanism – which remains known only internally at Mercedes – the situation is quintessential Formula 1. First and foremost, this is the political game in its purest form, as Zak Brown rightly pointed out. The McLaren CEO obviously has a stake in the matter, but he is correct in calling it a textbook example of paddock politics.

“It's typical politics of Formula 1,” he said. “The engine has been designed and totally compliant within the rules. That's what the sport is about. No different than things like double diffusers that we've seen in the past where they're compliant within the rules. I don't believe there's a significant advantage as being represented by the competition, but of course their job is any perceived advantage, they'll make a story out of it.”

The amusing part is that exactly the same thing is happening on both sides – just with a completely different narrative. Those pushing for change emphasise that Formula 1 should provide a level playing field, with rules that are clear for everyone involved.

The cases for and against argue the exact opposite points

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Those arguing against any amendment invoke the ‘DNA of the sport’ – a term that always resurfaces in these debates. Vowles warned that F1 risks becoming a BOP series, and Wolff unsurprisingly echoed similar sentiments.

“I would say that within the sport there are individuals which would want it to be a series with a BOP, without calling it a BOP, by saying we actually don't want engineering ingenuity, we'd prefer to have a level playing field,” the Mercedes boss said. “And therefore, we have some rules that are invented on the fly that make things even more complex.

“I think the very essence of Formula 1 is to find performance, to attract the best engineers and the best people, give them freedom to develop regulations and once it goes for you and another time it goes against you.”

While it would be overly dramatic to label a change in measurement method as a BOP, both sides genuinely have grounds to argue their case. And that is precisely what makes this issue so complex and so fascinating. Each camp can point to different sections of the regulations to support their position.

The Mercedes teams refer to Article C5.4.3, which states that a static test at ambient temperature is the only method by which the compression ratio is measured. Opponents rely on the more general Article 1.5, which states: “Formula 1 cars must comply with these regulations in their entirety at all times during a competition.”

Since the 16:1 compression ratio is explicitly written into the regulations, those manufacturers argue that all engines must comply with that figure at all times – including when running on track at higher temperatures. And, frankly, both sides have a point. There is a case to be made for each interpretation, meaning there is no clear-cut right or wrong. It is simply the outcome of how the rules have been drafted – and therefore the ball is firmly in the FIA’s court to decide which interpretation carries more weight.

The matter now rests on what the FIA decides

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Political battles are part of Formula 1’s DNA

Finally, it is important to stress that this debate is absolutely not just about performance. As an engine expert with many years of F1 experience told Autosport, adjusting the compression ratio can be highly consequential – especially if it is indeed linked to the materials used for the piston.

And here an old F1 law applies: if you have not found the trick yourself, there are two options. You can copy it, or you can lobby to have it banned.

The first option requires a deep understanding of exactly what is happening and comes at considerable cost. That makes option two well worth attempting. If successful – perhaps not even this year – Mercedes would be forced to make changes, effectively batting the ball back and inflicting the loss of valuable development time and budget under the cost cap on a rival.

Some fans may dislike it and prefer everything to be settled purely on track, but the political chess match is inseparable from the championship and has always been part of it

And that is precisely the game being played now: can you convince the FIA? And, in doing so, are you the one who is ‘screwed’, as Wolff put it, or can you trip up someone else? It is textbook F1 politics.

That said, an intervention this late in the process would undoubtedly be harsh – particularly as Mercedes claims it has kept the FIA involved throughout the design process. With the homologation deadline of 1 March looming, there is barely any time left to make adjustments. Any late change would also create an entirely new, and much bigger, problem for the FIA and F1 – namely, what to do with the Mercedes-powered teams in Melbourne?

A compromise therefore still seems plausible. But either way, this is exactly what makes F1 so compelling. Some fans may dislike it and prefer everything to be settled purely on track, but the political chess match is inseparable from the championship and has always been part of it.

Just think back to Colin Chapman’s reaction when the Lotus 88’s twin-chassis concept was banned – and all the political fallout that followed. So yes, if everyone is so eager to talk about the DNA of F1, one could argue that these political games are more intrinsic than anything else.

The bigger game of politicking has always been a part of F1

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