2026 Drama: Alleged engine loophole

[Hoffman900]

Guys, no one in the media has been given these numbers. Before this, I bet most of them even knew how to calculate geometric compression ratio. It’s all hersey because they’ve had nothing else to write about / generate clicks (which equal money).

[upsidedowntoast]

I remember that defensive Hodgkinson interview. You could be right and whatever I am reading online might be wrong. We will know either way in a week the advantage Mercedes carries. I suspect its a lot. But let's hope I am wrong.

What was this interview?

If I recall correctly most other manufacturers could expect their PU to be 16:1 at ambient, down to 15.8 or 15.9 at operating. Meanwhile Mercedes went from 16:1 at ambient, up to 16.3:1 at operating. After accounting for noise that would be an advantage of single digit horsepower, maybe 5-10 up until June 1, then down to 2-3 until 2027, which is in line what Wolff was claiming.

The longer this goes on the more it feels like a giant nothingburger to me, similar to the flexiwing debacle. If it really was a 2014-level advantage that they were hiding, there would actually be lawsuits and bribery going on. Not to mention going from 18:1 down to 16:1 would completely mess up their aero and fuel and god knows what else.

If it was 2014 advantage that would be 2s a lap like Nico and Lewis showed in Bahrain. It is impossible to be that far ahead when you remove the token system.

I only saw the 15.2/15.3 reported. Where did you see 15.8/15.9?

I am not sure what Mercedes is running at. All I know is others aren't at 16.

Also even if you are a Mercedes fan if you believe Wolff of all people there's no discussion to be had really.

1. The truth is we have no idea what the other teams' true compression ratios are. I hear "expected" is 15.2-15.3, but given that F1 engineers are all incredibly smart I would not be surprised that they're actually over that. The 15.8 number I will admit I read somewhere else on this forum.

2. I am not blindly believing Wolff. I am making my judgments based on the numbers available and basic math. The 2026 ICE side is 530-550 hp, each additional point in CR gets you something like 1-2% more hp (theoretical best case scenario), so therefore:

- 16.3 vs 15.3 = 5-11 hp
- 16.0 vs 15.3 = 4-8 hp
- 16.3 vs 15.8 = 3-6 hp
- 16.0 vs 15.8 = 1-3 hp

After accounting for noise and other inefficiencies, the real number seems closer to single digit hp gains than the 20-30 everyone else feared. And they seem far more realistic to me from a purely engineering perspective.

[dans79]

Just as an aside people need to keep in mind two coefficients are relevant. Both are important in an engine design.

• coefficient of thermal expansion
• coefficient thermal conductivity

[catent]

None of the teams do. Ferrari's monkey grill doesn't comply with the spirit of the rules around exhaust blown aero. Yet the FIA changed the dimensions of the permitted aero around the monkey grill multiple times, up until December 2025, to allow Ferrari to build it. All the teams have exploited flexi wings over the years.

There are the rules, and there are the tests for the rules. The goal for every team is to pass the tests.

Can you provide reference to the FIA changing the permitted dimensions for bodywork aerodynamic surfaces multiple times through December 2025? This is the first I am hearing of this. And if these dimensions were being changed up through December 2025, on what basis do you assert it was done at Ferrari's request, or to "allow" Ferrari to design this "monkey wing"? Can you provide evidence for this claim?

As for the comparison to the compression ratio situation, I don't think these situations are analogous. How are you inferring this intention/spirit regarding "exhaust blown aero"? They only way the FIA can enforce such "intention" is via objectively defined rules/regulations. Ferrari has fully complied with those regulations when implementing the "monkey wing".

Furthermore, Ferrari apparently vetted this solution with the FIA prior to implementing it. Mercedes may have asked for clarification regarding the conditions under which compression ratio was to be measured, but I highly doubt they directly asked the FIA, "if we are compliant during the pre-session check at ambient, are we still considered compliant if we exceed 16:1 during operation?", so I don't think anyone can fairly/accurately say Mercedes got "clearance" from the FIA for this alleged compression ratio trick. They merely received (messy) clarification regarding the measurement procedure, all the while not reconciling the very clear and obvious rule which explicitly caps compression ratio at 16:1.

As I see it, there are rules regarding bodywork dimensions and ICE compression ratio. Ferrari's "monkey wing" fully complies with those bodywork regulations in every regard, at all times. They made a deliberate design choice that allows them to implement such a solution which still being fully compliant with the rules as written at every moment the car is in operation. Regarding compression ratio, there is an explicitly stated compression ratio cap. There is no need to parse intention or spirit, because it is (and has always been) clearly stated in the 2026 regulations that compression ratio may not exceed 16:1 on any given cylinder. Full stop.

A better analogy would be if Ferrari's "monkey wing" changed dimensions when the car was running on the track, such that is no longer complied with bodywork regulations. But as far as I can tell, that's not what is actually happening.

[CHT]

[quote=upsidedowntoast post_id=1330762 time=1772482704 user_id=51579
1. The truth is we have no idea what the other teams' true compression ratios are. I hear "expected" is 15.2-15.3, but given that F1 engineers are all incredibly smart I would not be surprised that they're actually over that. The 15.8 number I will admit I read somewhere else on this forum.

2. I am not blindly believing Wolff. I am making my judgments based on the numbers available and basic math. The 2026 ICE side is 530-550 hp, each additional point in CR gets you something like 1-2% more hp (theoretical best case scenario), so therefore:

- 16.3 vs 15.3 = 5-11 hp
- 16.0 vs 15.3 = 4-8 hp
- 16.3 vs 15.8 = 3-6 hp
- 16.0 vs 15.8 = 1-3 hp

After accounting for noise and other inefficiencies, the real number seems closer to single digit hp gains than the 20-30 everyone else feared. And they seem far more realistic to me from a purely engineering perspective.
[/quote]

Engine with higher peak operating temperature may possibly gain more from thermal expansion.

[Hoffman900]

Higher compression reduces cylinder gas temperatures during the power phase dona greater expansion. So it’s hotter in some ways and cooler in others.

Like anything, the answer is “it’s complicated”

[Arcanum]

Can you provide reference to the FIA changing the permitted dimensions for bodywork aerodynamic surfaces multiple times through December 2025? This is the first I am hearing of this. And if these dimensions were being changed up through December 2025, on what basis do you assert it was done at Ferrari's request, or to "allow" Ferrari to design this "monkey wing"? Can you provide evidence for this claim?

Article published by The Race: https://www.the-race.com/formula-1/the- ... cant-copy/

I know some people here don't like TR, but would assume that the multiple iterations of the rules bounding the RV-Tail cross-section can be easily cross-checked if someone wishes.

As for the comparison to the compression ratio situation, I don't think these situations are analogous. How are you inferring this intention/spirit regarding "exhaust blown aero"? The only way the FIA can enforce such "intention" is via objectively defined rules/regulations. Ferrari has fully complied with those regulations when implementing the "monkey wing".

See this: https://motorsport.tech/formula-1/f1-te ... om-bahrain

The key comment from the article being: There is no longer a regulation stipulating a clear area behind the exhaust tailpipe, which had been previously used to prevent blown solutions such as this. The tail bodywork rules were expected to achieve this.

Prior to 2026, there were rules about preventing EBD, but it seems that the FIA thought it was no longer necessary to have that because of how the tail bodywork was dimensioned. Ferrari have found a way through that, and it will be interesting to see if there is an update for 2027. The intent has been to prevent EBD during the last rule cycles, and Ferrari have found a novel way through it.

I take your point that there are some differences between what Ferrari have done and what Mercedes are rumored to have done. Yet people in this thread have been talking about intent and spirit of the rules. EBD is not in the spirit of the rules, and the FIA obviously thought it wasn't possible, but Ferrari have found a way through - and if this area is tightened up for next year and the monkey grill not possible, it will be obvious that the FIA are correcting an oversight in the rules. Ultimately, teams need to comply with the tests. If Mercedes comply at both ambient and 130C, they are legal.

[Frank73]

Can you provide reference to the FIA changing the permitted dimensions for bodywork aerodynamic surfaces multiple times through December 2025? This is the first I am hearing of this. And if these dimensions were being changed up through December 2025, on what basis do you assert it was done at Ferrari's request, or to "allow" Ferrari to design this "monkey wing"? Can you provide evidence for this claim?

Article published by The Race: https://www.the-race.com/formula-1/the- ... cant-copy/

I know some people here don't like TR, but would assume that the multiple iterations of the rules bounding the RV-Tail cross-section can be easily cross-checked if someone wishes.

As for the comparison to the compression ratio situation, I don't think these situations are analogous. How are you inferring this intention/spirit regarding "exhaust blown aero"? The only way the FIA can enforce such "intention" is via objectively defined rules/regulations. Ferrari has fully complied with those regulations when implementing the "monkey wing".

See this: https://motorsport.tech/formula-1/f1-te ... om-bahrain

The key comment from the article being: There is no longer a regulation stipulating a clear area behind the exhaust tailpipe, which had been previously used to prevent blown solutions such as this. The tail bodywork rules were expected to achieve this.

Prior to 2026, there were rules about preventing EBD, but it seems that the FIA thought it was no longer necessary to have that because of how the tail bodywork was dimensioned. Ferrari have found a way through that, and it will be interesting to see if there is an update for 2027. The intent has been to prevent EBD during the last rule cycles, and Ferrari have found a novel way through it.

I take your point that there are some differences between what Ferrari have done and what Mercedes are rumored to have done. Yet people in this thread have been talking about intent and spirit of the rules. EBD is not in the spirit of the rules, and the FIA obviously thought it wasn't possible, but Ferrari have found a way through - and if this area is tightened up for next year and the monkey grill not possible, it will be obvious that the FIA are correcting an oversight in the rules. Ultimately, teams need to comply with the tests. If Mercedes comply at both ambient and 130C, they are legal.

If CR trick is based on a second chamber, than it is not legal, despite being rule-compliant geometry-wise at all temperatures.

[catent]

Can you provide reference to the FIA changing the permitted dimensions for bodywork aerodynamic surfaces multiple times through December 2025? This is the first I am hearing of this. And if these dimensions were being changed up through December 2025, on what basis do you assert it was done at Ferrari's request, or to "allow" Ferrari to design this "monkey wing"? Can you provide evidence for this claim?

Article published by The Race: https://www.the-race.com/formula-1/the- ... cant-copy/

I know some people here don't like TR, but would assume that the multiple iterations of the rules bounding the RV-Tail cross-section can be easily cross-checked if someone wishes.

As for the comparison to the compression ratio situation, I don't think these situations are analogous. How are you inferring this intention/spirit regarding "exhaust blown aero"? The only way the FIA can enforce such "intention" is via objectively defined rules/regulations. Ferrari has fully complied with those regulations when implementing the "monkey wing".

See this: https://motorsport.tech/formula-1/f1-te ... om-bahrain

The key comment from the article being: There is no longer a regulation stipulating a clear area behind the exhaust tailpipe, which had been previously used to prevent blown solutions such as this. The tail bodywork rules were expected to achieve this.

Prior to 2026, there were rules about preventing EBD, but it seems that the FIA thought it was no longer necessary to have that because of how the tail bodywork was dimensioned. Ferrari have found a way through that, and it will be interesting to see if there is an update for 2027. The intent has been to prevent EBD during the last rule cycles, and Ferrari have found a novel way through it.

I take your point that there are some differences between what Ferrari have done and what Mercedes are rumored to have done. Yet people in this thread have been talking about intent and spirit of the rules. EBD is not in the spirit of the rules, and the FIA obviously thought it wasn't possible, but Ferrari have found a way through - and if this area is tightened up for next year and the monkey grill not possible, it will be obvious that the FIA are correcting an oversight in the rules. Ultimately, teams need to comply with the tests. If Mercedes comply at both ambient and 130C, they are legal.

There is no evidence in the article you shared that supports the claim that Ferrari lobbied the FIA for rules changes regarding bodywork dimensions so they could implement this specific design. There is mention that Ferrari was in contact with the FIA to ensure that this device is legal/permitted before implementing it, but there is no evidence that they specifically lobbied for rule changes in order to accommodate this device.

In fact, the bodywork dimensions you reference were changed four times between 11 December 2024 and 10 December 2025 (a calendar year). Surely, if the FIA felt this solution was beyond what they intended, they could have told Ferrari as much and modified these bodywork dimensions yet again, to effectively prohibit such a solution. The FIA did not do so.

That article doesn't support the narrative that a rule change (regarding bodywork dimensions) was made late in the process at Ferrari's request in order to legalize this 'monkey wing'. There is no evidence for that assertion.

[LM10]

Can you provide reference to the FIA changing the permitted dimensions for bodywork aerodynamic surfaces multiple times through December 2025? This is the first I am hearing of this. And if these dimensions were being changed up through December 2025, on what basis do you assert it was done at Ferrari's request, or to "allow" Ferrari to design this "monkey wing"? Can you provide evidence for this claim?

Article published by The Race: https://www.the-race.com/formula-1/the- ... cant-copy/

I know some people here don't like TR, but would assume that the multiple iterations of the rules bounding the RV-Tail cross-section can be easily cross-checked if someone wishes.

As for the comparison to the compression ratio situation, I don't think these situations are analogous. How are you inferring this intention/spirit regarding "exhaust blown aero"? The only way the FIA can enforce such "intention" is via objectively defined rules/regulations. Ferrari has fully complied with those regulations when implementing the "monkey wing".

See this: https://motorsport.tech/formula-1/f1-te ... om-bahrain

The key comment from the article being: There is no longer a regulation stipulating a clear area behind the exhaust tailpipe, which had been previously used to prevent blown solutions such as this. The tail bodywork rules were expected to achieve this.

Prior to 2026, there were rules about preventing EBD, but it seems that the FIA thought it was no longer necessary to have that because of how the tail bodywork was dimensioned. Ferrari have found a way through that, and it will be interesting to see if there is an update for 2027. The intent has been to prevent EBD during the last rule cycles, and Ferrari have found a novel way through it.

I take your point that there are some differences between what Ferrari have done and what Mercedes are rumored to have done. Yet people in this thread have been talking about intent and spirit of the rules. EBD is not in the spirit of the rules, and the FIA obviously thought it wasn't possible, but Ferrari have found a way through - and if this area is tightened up for next year and the monkey grill not possible, it will be obvious that the FIA are correcting an oversight in the rules. Ultimately, teams need to comply with the tests. If Mercedes comply at both ambient and 130C, they are legal.

The rule is clear, it’s black on white. No loophole, no interpretation games. Nothing to tighten up. If you allow bodywork in that region right behind the exhaust you logically expect it to be blown at. The FIA very well thought about it and they knew it was possible.

Also, this is neither to be compared with flexi wings nor with CR trickery. Once it’s deemed legal it stays legal because it will not change its form in changing conditions.

[Frank73]

Can you provide reference to the FIA changing the permitted dimensions for bodywork aerodynamic surfaces multiple times through December 2025? This is the first I am hearing of this. And if these dimensions were being changed up through December 2025, on what basis do you assert it was done at Ferrari's request, or to "allow" Ferrari to design this "monkey wing"? Can you provide evidence for this claim?

Article published by The Race: https://www.the-race.com/formula-1/the- ... cant-copy/

I know some people here don't like TR, but would assume that the multiple iterations of the rules bounding the RV-Tail cross-section can be easily cross-checked if someone wishes.

As for the comparison to the compression ratio situation, I don't think these situations are analogous. How are you inferring this intention/spirit regarding "exhaust blown aero"? The only way the FIA can enforce such "intention" is via objectively defined rules/regulations. Ferrari has fully complied with those regulations when implementing the "monkey wing".

See this: https://motorsport.tech/formula-1/f1-te ... om-bahrain

The key comment from the article being: There is no longer a regulation stipulating a clear area behind the exhaust tailpipe, which had been previously used to prevent blown solutions such as this. The tail bodywork rules were expected to achieve this.

Prior to 2026, there were rules about preventing EBD, but it seems that the FIA thought it was no longer necessary to have that because of how the tail bodywork was dimensioned. Ferrari have found a way through that, and it will be interesting to see if there is an update for 2027. The intent has been to prevent EBD during the last rule cycles, and Ferrari have found a novel way through it.

I take your point that there are some differences between what Ferrari have done and what Mercedes are rumored to have done. Yet people in this thread have been talking about intent and spirit of the rules. EBD is not in the spirit of the rules, and the FIA obviously thought it wasn't possible, but Ferrari have found a way through - and if this area is tightened up for next year and the monkey grill not possible, it will be obvious that the FIA are correcting an oversight in the rules. Ultimately, teams need to comply with the tests. If Mercedes comply at both ambient and 130C, they are legal.

There is no evidence in the article you shared that supports the claim that Ferrari lobbied the FIA for rules changes regarding bodywork dimensions so they could implement this specific design. There is mention that Ferrari was in contact with the FIA to ensure that this device is legal/permitted before implementing it, but there is no evidence that they specifically lobbied for rule changes in order to accommodate this device.

In fact, the bodywork dimensions you reference were changed four times between 11 December 2024 and 10 December 2025 (a calendar year). Surely, if the FIA felt this solution was beyond what they intended, they could have told Ferrari as much and modified these bodywork dimensions yet again, to effectively prohibit such a solution. The FIA did not do so.

That article doesn't support the narrative that a rule change (regarding bodywork dimensions) was made late in the process at Ferrari's request in order to legalize this 'monkey wing'. There is no evidence for that assertion.

Of course there was no on-demand rule change. It would have triggered controversies as harsh as those for the CR gate.

[LM10]

It is a nothing burger.

If Mercedes had the micro-hole might as well they have a 18:1 compression ratio, and it doesn't matter what tempersture the CR is measured at, it will beat the system. And doing that would break the spirit of the rules. This is why I don't think they are doing it.

Because Mercedes is known for caring for the spirit of the rules?

You say it like other teams are innocent saints lmao

The argument was that Mercedes would not do something breaking the spirit of the rules and this is factually incorrect, which I pointed out.

[Arcanum]

I bet the FIA refine the rules in the area of Monkey grill to outlaw it for next year. They've not wanted EBD in the last rule cycle, and I doubt they decided that someone stretching gearbox design to exploit EBD in this rule cycle was desirable either. Again, my bet is that the FIA outlaw this in 2027. Like DAS, there will be a year for Ferrari to enjoy the benefit, then it will be gone.

The FIA refining dimensions in the area that Ferrari are working is suspicious. Sure, there is no evidence they lobbied the FIA, that is fair. Equally there is no evidence that Mercedes has a second combustion chamber, is at 18:1 CR or whatever else has been suggested around here. Just suspicions Merc are illegal because they did push (lobby) for a rule clarification to measure CR at ambient. Yet as the PU working group had the ability to come up with any test they liked to expose Merc, and the best they could come up with is a 130C hot-test which Merc seemingly passes, there's not any proof Merc have done anything wrong either. Surely the PU working group, with all their expertise, could have designed something to expose Merc's cheating? On the other hand, maybe the PU working group just don't have the expertise and knowledge of the posters in this thread?

People just don't like Mercedes. Fair enough. I don't like them as a team either. I particularly dislike Toto Wolf's style. Doesn't mean they've done something illegal.

[bluechris]

We will see what will happen next year no worries. All the latest decisions favor one specific team and this is a fact. Maybe a TD39B can be implemented after Melbourne to ban it immediately even if it's legal according to the rules. We have used to this many years now.

[f1isgood]

I bet the FIA refine the rules in the area of Monkey grill to outlaw it for next year. They've not wanted EBD in the last rule cycle, and I doubt they decided that someone stretching gearbox design to exploit EBD in this rule cycle was desirable either. Again, my bet is that the FIA outlaw this in 2027. Like DAS, there will be a year for Ferrari to enjoy the benefit, then it will be gone.

The FIA refining dimensions in the area that Ferrari are working is suspicious. Sure, there is no evidence they lobbied the FIA, that is fair. Equally there is no evidence that Mercedes has a second combustion chamber, is at 18:1 CR or whatever else has been suggested around here. Just suspicions Merc are illegal because they did push (lobby) for a rule clarification to measure CR at ambient. Yet as the PU working group had the ability to come up with any test they liked to expose Merc, and the best they could come up with is a 130C hot-test which Merc seemingly passes, there's not any proof Merc have done anything wrong either. Surely the PU working group, with all their expertise, could have designed something to expose Merc's cheating? On the other hand, maybe the PU working group just don't have the expertise and knowledge of the posters in this thread?

People just don't like Mercedes. Fair enough. I don't like them as a team either. I particularly dislike Toto Wolf's style. Doesn't mean they've done something illegal.

In F1 there are rules and there are tests. As a team you are supposed to comply by the rules always. If you cheat the test then you are only not caught yet. But if you do stupid things and get caught because the test changed, be ready to win stupid prizes. Applies to every team. If Mercedes get nerfed, then they clearly did something that others didn't like and even with 8 cars on the grid couldn't resist the change -- I guess that's a good thing for F1 after all. Clearly there would be nothing to say here if Mercedes actually did something that was expected and in line.

So far nothing has suggested other teams think Ferrari is doing something illegal. If they are, you dont need to worry, there'll be drama from Mercedes, McLaren and Red Bull in no time. Trying to draw comparisons without substance is not a good idea imo.

Also the good thing nowadays is that technical people like a certain Ferrari fan a couple of years ago can actually bring about rule changes. Thats a good thing for the sport as it at least keeps blatant cheating away.

In reality you can always say everyone cheats. Probably true in practice but it leads to no discussion in the end.

Part of the reason why Mercedes' story might have even leaked might have been the endless stories they leaked likely themselves of their superiority for a year at this point.

A comment in the race article says the revision was made in June 2025 BTW. I dont know if its true but if true seems like other teams missed an area of free performance.