In an interview posted on the FIA’s YouTube Channel, FIA Single Seater Director Nikolas Tombazis and FIA Single Seater Technical Director Jan Monchaux talk about the 2026 F1 Regulations and weigh in on the compression ratio debate.
With the introduction of the 2026 F1 Regulations, the FIA lowered the compression ratio limit from 18:1 to 16:1. In recent weeks, rumors arose that suggested that at least one engine manufacturer, Mercedes, has found a way to increase the compression ratio while the car is running, while staying within the limits outlined in the Regulations when FIA tests are conducted. According to the 2026 F1 Regulations, these tests are conducted at ambient temperatures, which reportedly created the loophole Mercedes reportedly exploited.
Tzombasis explains that it is “quite complicated” to build an engine that can run at high compression, but if done correctly, it can result in a “more efficient” engine.
Compression ratio explained
“I mean, first of all, compression ratio is just a bit of a very, very basic engine, a four-stroke engine, which is what most road cars have had for the last 100 plus years. And what most racing cars have is an engine where there’s a piston, or many pistons, moving up and down and turning around the crankshaft.
“And when they move, the fuel and the air come into the engine, and the piston moves down. And then it moves back up again without producing any power. The other cylinders are pushing it up. At that moment, it compresses the fuel, the gas, and the air into a very, very small volume.
“So, how much fuel has gone in and air to how much it actually compresses to that proportion is the compression ratio, the higher that is. And then after that, you have an inflexion, you know, combustion of that mixture that pushes down and produces the power.”
“The higher that compression ratio is, the more generally speaking, the more efficient the engine is. Now, you can’t overdo it. If you go too high, then you start having other issues, like it will get too hot, and then it will pre-combust.
“And that’s what we call knock. And that’s sometimes you see that on your old car. Maybe the older ones, if you press, if you’re on a very high gear and you’re going very slowly, you hear this knocking sound.
“It gets quite complicated to design those super sophisticated engines with that number being very high.”
The reason behind the FIA lowering the compression ratio with the 2026 F1 regulations
The 2026 F1 regulations were intended to incentivize new teams to join the F1 grid. To allow new teams to join, adjustments to the existing regulations were needed to ensure a “fair playing field.” Otherwise, the cost cap and other restrictions would have left new teams struggling to “catch up,” according to Tzombasis. Lowering the compression ratio from 18:1 to 16:1 was one of the changes born out of the FIA’s desire to level out the playing field.
“Of course, we wanted with these regulations in the early days to invite newcomers. And I think we’ve been quite successful.
“We have five PU manufacturers at the moment and one on the way of coming into sport. If we had not made those changes, I think we would probably have two by now. We’d have only two, and that would have been a problem.
“So, because all of these newcomers have started way behind the established ones, we had to create some ways that would enable these newcomers to join the sport on a fair playing field. Otherwise, they would have been way behind. And as there’s a cost gap, as there are limitations. They would have always been struggling to catch up. It’s still going to be massively challenging for them.
“It’s not an easy task. And that’s why part of the condition for these guys to come in was to create some simplification and cost reduction. And the compression ratio was one of those.
“That was the reason we went from what used to be a limit of 18:1, which frankly was almost not a limit, because you could hardly reach that level, to 16:1, which is a bit of a compromise.”
FIA on the current discussion surrounding the compression ratio
Weighing in on the current debate about the compression ratio, the FIA Single Seater Director notes that F1 engineers are “very clever” in finding new ways to gain an advantage. Tzombasis states that the FIA is holding ongoing discussions and seeking to resolve issues with the 2026 F1 Regulations ahead of the start of the season.
“And of course, as these engineers are very clever and always pushing for an advantage, some have found ways to potentially increase it when the engine is running hot. And that is the discussion we’re having now.
“I mean, we’ve spent a lot of time with Jan [Monchaux] discussing how we solve those issues. And I think our intention is, of course, to solve them for the start of the season. We don’t want to have controversies.
“We want people to be competing on the track and not in the courtroom or in the steward’s room. And that’s what we’re trying to do.”
FIA expects that the compression ratio will not remain the only topic
As the FIA attempts to settle the compression ratio debate ahead of the 2026 F1 season, the FIA Single Seater Director believes that it will not remain the only topic arising from the 2026 F1 Regulations. Tzombasis believes that teams will identify new areas as they strive to gain an advantage over their competitors and that the FIA works with the teams to ensure they are all on the same page regarding their understanding of the 2026 F1 Regulations.
“Yes, I mean, I think it’s also a numbers game we need to explain. Obviously, perfection is when there’s no discussion about any aspect of the regulation, if everything is completely as intended, no interpretations, and everyone understands perfectly. That is our objective. That’s what we strive for. And I think we’ve made a lot of progress in that.
“When regulations change a lot, a lot of unforeseen circumstances come about. We work a lot with the teams and the PU manufacturers. We have meetings. Each team has maybe 200 engineers or so amongst the 1,000 people working for the car, sometimes a bit more.”
Clever interpretations of the 2026 F1 regulations are unavoidable
Given that all F1 teams combined employ thousands of engineers, Tzombasis feels it is unavoidable that a group of engineers will find weaknesses in the Regulations that are then exploited to gain an advantage. The FIA Single Seater Director notes that this phenomenon has always been part of the sport, but that the FIA seeks not to have the Championship be determined by a team’s interpretation of the 2026 F1 Regulations.
“We have maybe 2,000 engineers in the teams and maybe another, I don’t know, 1,000 or so in the engine and PU manufacturers. So it’s invaluable that amongst those many thousands to the 10 or so, that sometimes they will come up with something that nobody has thought.
“It’s also quite significant to think that you have 11 teams and five PU manufacturers, and not all of those identify these weak areas, which means that you have 200 people in one team, and maybe out of those 200 people, nobody has thought there’s a little area to use.
“What I’m trying to say is that it’s a numbers and statistics game. And it’s impossible when we have new rules not to have such areas of discussion. That’s always been the case.
“I think what has changed is that we are determined to make this a championship of competition between the best drivers, the best engineers, the teams, but not a championship of rule interpretation. We want it to be a championship of engineering prowess as well as driving prowess, but not actually just to say a smarter rule interpretation.”
