2026 Drama: Alleged engine loophole

[fourmula1]

I think what you meant to say is: Only when a team that I don't support does it, then it's illegal.

I’d say I am a very long time Ferrari fan. Please provide more examples to support either way. RB Cost cap was black and white breach? Ferrari bypassing fuel flow sensor is pretty black and white? Also my hypothetical conversion that you removed from quote between Merc and FIA contextualizes the other comments. The best part of all of this is we still have no idea what is really going on.

There's nothing to contextualize. I repeat again that words like: "blatantly hiding the way you are cheating" are COMPLETELY out of place. We either choose that being legal means respecting the test procedure, or we choose that being legal means respecting the rule how it's written. What we cannot do is flip flop between the 2 and claim that someone is cheating more blatantly than another, because especially us forum goers know nothing of how "blatant" anything is. If Ferrari cheating was so blatant then they would have been found out without all the fuss that was generated.

Any car is illegal if you check it long enough. This is not a moral stand, or some teams being more evil than others, they all do their job of finding an advantage.

lol…I agree…I don’t know why you think I am advocating for anything. I am merely making observations and speculating that F1 parties and interests allow testing to rule legality, and that there will always be a grey area, my example of grey area in how the FIA responds would be Ferrari fuel flow example vs flexiwings.

[spade16]

The other teams have been remarkably quiet on the issue so either they got what they wanted or they know that there is no chance of the FIA coming up with a test that will actually find out if anyone is exceeding the 16:1 ratio

Toto seems completely fine with it so i suspect they know they got away with something and I doubt they will even have to make a change when the new testing comes into force in August. I think they will turn down all the engines (including the customer PU’s) in Melbourne so they don’t win by too much

[nitrotech]

chatgpt explanation of the situation. This is why, newly proposed hot and cold test might hurt all PU manufacturers and hence might not get required voting to pass it.

## What the regulation says

The **Fédération Internationale de l'Automobile** mandates a **maximum 16:1 compression ratio** for the 2026 power units.

Compression ratio depends on:

* Combustion chamber volume
* Piston crown geometry
* Clearances
* And how all of that changes with **temperature (thermal expansion)**

---

## What “hot-only test” would allow

If the FIA only tests engines at **operating temperature (~130°C)**:

Manufacturers could design the engine so that:

* When cold → compression ratio is **above 16:1** (e.g. 16.2:1)
* When hot → thermal expansion causes chamber volume to increase slightly, bringing it **down to exactly 16:1**

In that scenario:

* The engine passes inspection (because inspection is hot-only)
* But the geometric design is technically outside the limit at cold

So they would be optimizing the engine assuming it will only ever be measured hot.

---

## Why that might be attractive

Designing it slightly over 16:1 when cold could allow:

* More aggressive combustion chamber geometry
* Tighter clearances
* Potential efficiency gains
* Better combustion shaping at operating temperature

Basically:
They tune the engine so that **its “true performance state” (hot) sits right on the legal limit**, even if it technically exceeds it when cold.

---

## Why adding a cold test blocks this

If the FIA requires **both cold AND hot compliance**, then:

* You cannot exceed 16:1 in either condition.
* You lose the ability to “design through temperature.”
* You must stay under the limit across the full thermal range.

That removes a clever engineering margin.

---

## Why this creates political tension

So now there are potentially two opposite strategies:

* One camp allegedly designed engines that exceed 16:1 when hot.
* Another camp may have designed engines that exceed 16:1 when cold but drop to 16:1 when hot.

A hot-only test would hurt the first group.
A cold-only test would hurt the second group.
A dual test hurts both.

That’s why the voting dynamics suddenly shifted.

---

In simple terms:

> A hot-only test lets you “hide” excess compression at cold.
> A cold-only test lets you “hide” excess compression at hot.
> Testing both removes both tricks.

Hemce, the conclusion is, potentially, ALL manufacturers have illegal engines in either scenarios and faill "Compliance in all conditions" clause.

[upsidedowntoast]

chatgpt explanation of the situation. This is why, newly proposed hot and cold test might hurt all PU manufacturers and hence might not get required voting to pass it.

## What the regulation says

The **Fédération Internationale de l'Automobile** mandates a **maximum 16:1 compression ratio** for the 2026 power units.

Compression ratio depends on:

* Combustion chamber volume
* Piston crown geometry
* Clearances
* And how all of that changes with **temperature (thermal expansion)**

---

## What “hot-only test” would allow

If the FIA only tests engines at **operating temperature (~130°C)**:

Manufacturers could design the engine so that:

* When cold → compression ratio is **above 16:1** (e.g. 16.2:1)
* When hot → thermal expansion causes chamber volume to increase slightly, bringing it **down to exactly 16:1**

In that scenario:

* The engine passes inspection (because inspection is hot-only)
* But the geometric design is technically outside the limit at cold

So they would be optimizing the engine assuming it will only ever be measured hot.

---

## Why that might be attractive

Designing it slightly over 16:1 when cold could allow:

* More aggressive combustion chamber geometry
* Tighter clearances
* Potential efficiency gains
* Better combustion shaping at operating temperature

Basically:
They tune the engine so that **its “true performance state” (hot) sits right on the legal limit**, even if it technically exceeds it when cold.

---

## Why adding a cold test blocks this

If the FIA requires **both cold AND hot compliance**, then:

* You cannot exceed 16:1 in either condition.
* You lose the ability to “design through temperature.”
* You must stay under the limit across the full thermal range.

That removes a clever engineering margin.

---

## Why this creates political tension

So now there are potentially two opposite strategies:

* One camp allegedly designed engines that exceed 16:1 when hot.
* Another camp may have designed engines that exceed 16:1 when cold but drop to 16:1 when hot.

A hot-only test would hurt the first group.
A cold-only test would hurt the second group.
A dual test hurts both.

That’s why the voting dynamics suddenly shifted.

---

In simple terms:

> A hot-only test lets you “hide” excess compression at cold.
> A cold-only test lets you “hide” excess compression at hot.
> Testing both removes both tricks.

Hemce, the conclusion is, potentially, ALL manufacturers have illegal engines in either scenarios and faill "Compliance in all conditions" clause.

This still makes zero sense to me. Historically compression ratio tests have always been conducted at ambient temperature. I cannot think of a single manufacturer who would have designed their engine to be noncompliant at ambient but compliant at hot, as if they could bank on this "hot-only" proposal passing.

Nor can I think of a method where the engine was originally designed with 16:1 ambient in mind based on the old ruleset, that can be easily modified to >16:1 ambient and 16:1 hot should a "hot-only" proposal pass.

Nor can I think of a reason why a non-Merc team would vote down the "hot test" proposal to give themselves a slight advantage when it would hurt Mercedes much more.

I have no idea where the guys at The Race got this story. If it's even a story at all.

[AR3-GP]

https://x.com/i/status/2024990488290377753

This is interesting esp since Alpine confirmed it

Is this really a "more powerful" spec or just the spec modified to handle the compression ratio brouhaha come August

[Hoffman900]

As someone who actually has built race engines, and has repeated this a thousand times in this thread, all engines will gain geometric compression in-situ approaching redline vs ambient. This is literally just physics.

​Everyone who has built more than a few engines in their life knows you build race engines with like 1-1.5mm of piston to head clearance ambient, knowing you want to be near 0.1mm or so running clearance. Most engines will see a whole point of geometric compression gain or more (depending) in-situ at redline vs ambient.

But the whole F1 media sphere are people with journalism degrees, tabloid / click bait reporters / youtubers, and Reddit / forums ar just bunch of 14yo’s using ChatGPT to try to sound smart, so no one chatting about this outloud understands this

Also Binotto is playing politics to save face to Audi and their shareholders because they’re probably not going to be very fast this year. “They’re cheating because we’re cheating and they’re beating us” kind of thing​

Time and time again, you all show you’re more interested in arguing than actually learning, and this was all shared with you all, by not just me, dozens of pages ago.

[AR3-GP]

As someone who actually has built race engines, and has repeated this a thousand times in this thread, all engines will gain geometric compression in-situ approaching redline vs ambient. This is literally just physics.

​Everyone who has built more than a few engines in their life knows you build race engines with like 1-1.5mm of piston to head clearance ambient, knowing you want to be near 0.1mm or so running clearance. Most engines will see a whole point of geometric compression gain or more (depending) in-situ at redline vs ambient.

But the whole F1 media sphere are people with journalism degrees, tabloid / click bait reporters / youtubers, and Reddit / forums ar just bunch of 14yo’s using ChatGPT to try to sound smart, so no one chatting about this outloud understands this

Also Binotto is playing politics to save face to Audi and their shareholders because they’re probably not going to be very fast this year. “They’re cheating because we’re cheating and they’re beating us” kind of thing​

Time and time again, you all show you’re more interested in arguing than actually learning, and this was all shared with you all, by not just me, dozens of pages ago.

What is the point of repeating the same things over and over again that don't have anything to do with the topic and are also wrong?

A former power unit technical boss has explained to The Race that typically an engine with a 16:1 compression ratio when cold would drop to around 15.2-15.2:1 in operation because although the con rod expands, the block expands more.

https://www.the-race.com/formula-1/merc ... -proposal/


Toto Wolff also confirmed the existence of a trick that works against the norms. He also said his team would be impacted detrimentally if the rules were changed.

"There's a governance process. If that governance votes for a change to the engine regulations, you have to accept it. It is what it is. This would be detrimental to all teams powered by Mercedes engines in such a scenario."

"The benefit this would bring us is just a few horsepower."

"We will always respect the sport's governance. If the sport's management makes a decision against or in favor of our position, we have to comply with both."

We now know that in F1 ICE the geometric compression ratio normally goes down at operating temperature because a former F1 PU boss told us so. We also know that the Mercedes engine is abnormal because Toto Wolff told us so. I hope that clears things up.

[Hoffman900]

As someone who actually has built race engines, and has repeated this a thousand times in this thread, all engines will gain geometric compression in-situ approaching redline vs ambient. This is literally just physics.

​Everyone who has built more than a few engines in their life knows you build race engines with like 1-1.5mm of piston to head clearance ambient, knowing you want to be near 0.1mm or so running clearance. Most engines will see a whole point of geometric compression gain or more (depending) in-situ at redline vs ambient.

But the whole F1 media sphere are people with journalism degrees, tabloid / click bait reporters / youtubers, and Reddit / forums ar just bunch of 14yo’s using ChatGPT to try to sound smart, so no one chatting about this outloud understands this

Also Binotto is playing politics to save face to Audi and their shareholders because they’re probably not going to be very fast this year. “They’re cheating because we’re cheating and they’re beating us” kind of thing​

Time and time again, you all show you’re more interested in arguing than actually learning, and this was all shared with you all, by not just me, dozens of pages ago.

What is the point of repeating the same things over and over again that don't have anything to do with the topic and are also wrong?

You’re all arguing over something that you all have no knowledge of and it is super obvious to us that do, and you’ve been told by a few of us how this “Mercedes” trick isn’t even a trick and exists in all engines.

It’s “novel” to the F1 mediasphere because none of them have engineering and / or motorsports backgrounds and it’s all material to produce clicks for them anyway.

[AR3-GP]

What is the point of repeating the same things over and over again that don't have anything to do with the topic and are also wrong?

You’re all arguing over something that you all have no knowledge of and it is super obvious to us that do, and you’ve been told by a few of us how this “Mercedes” trick isn’t even a trick and exists in all engines.

It's not my argument. They are not my words. They are the points of senior F1 figures. You are contradicting them.

A former power unit technical boss has explained to The Race that typically an engine with a 16:1 compression ratio when cold would drop to around 15.2-15.2:1 in operation because although the con rod expands, the block expands more.

https://www.the-race.com/formula-1/merc ... -proposal/

Focus on this quote. Digest it.

[f1isgood]

Just curious, wouldn't going from 16:1 to 15.2:1 more than a five percent change in the compression ratio. That seems completely unreal to me to just happen from thermal expansion.

[catent]

As someone who actually has built race engines, and has repeated this a thousand times in this thread, all engines will gain geometric compression in-situ approaching redline vs ambient. This is literally just physics.

​Everyone who has built more than a few engines in their life knows you build race engines with like 1-1.5mm of piston to head clearance ambient, knowing you want to be near 0.1mm or so running clearance. Most engines will see a whole point of geometric compression gain or more (depending) in-situ at redline vs ambient.

But the whole F1 media sphere are people with journalism degrees, tabloid / click bait reporters / youtubers, and Reddit / forums ar just bunch of 14yo’s using ChatGPT to try to sound smart, so no one chatting about this outloud understands this

Also Binotto is playing politics to save face to Audi and their shareholders because they’re probably not going to be very fast this year. “They’re cheating because we’re cheating and they’re beating us” kind of thing​

Time and time again, you all show you’re more interested in arguing than actually learning, and this was all shared with you all, by not just me, dozens of pages ago.

Anyone participating in this conversation who isn't fully aligned with my perspective, is immature, clueless, and has no business discussing the topic.

Complaints from other teams, like the actual engineers who participate in the sport? They're just bitter and playing politics to save face.

And, oh by the way, shame on all of you approaching this discussion with subjective speculation and argumentation, rather than coming in with an open-mind and willingness to learn.

LOL

Can't make up this level of hypocrisy.

[AR3-GP]

Just curious, wouldn't going from 16:1 to 15.2:1 more than a five percent change in the compression ratio. That seems completely unreal to me to just happen from thermal expansion.

It doesn't require much. It is just a 0.299mm difference in the expansion of the head compared to the piston to drop the compression ratio down from 16 to 15.2.

edit: update to reflect the correct connecting rod length

[AR3-GP]

There's also one simple fact. If the change to the test wouldn't affect Mercedes, then they won't vote no to the reg change. Voting no would prove they can't pass the new test.

[mcdenife]

There's also one simple fact. If the change to the test wouldn't affect Mercedes, then they won't vote no to the reg change. Voting no would prove they can't pass the new test.

So proof someone is not a witch….try to drown them…if they live, they are a witch and if they drown/die, then they are ok, ie not a witch..bravo

[Hoffman900]

As someone who actually has built race engines, and has repeated this a thousand times in this thread, all engines will gain geometric compression in-situ approaching redline vs ambient. This is literally just physics.

​Everyone who has built more than a few engines in their life knows you build race engines with like 1-1.5mm of piston to head clearance ambient, knowing you want to be near 0.1mm or so running clearance. Most engines will see a whole point of geometric compression gain or more (depending) in-situ at redline vs ambient.

But the whole F1 media sphere are people with journalism degrees, tabloid / click bait reporters / youtubers, and Reddit / forums ar just bunch of 14yo’s using ChatGPT to try to sound smart, so no one chatting about this outloud understands this

Also Binotto is playing politics to save face to Audi and their shareholders because they’re probably not going to be very fast this year. “They’re cheating because we’re cheating and they’re beating us” kind of thing​

Time and time again, you all show you’re more interested in arguing than actually learning, and this was all shared with you all, by not just me, dozens of pages ago.

Anyone participating in this conversation who isn't fully aligned with my perspective, is immature, clueless, and has no business discussing the topic.

Complaints from other teams, like the actual engineers who participate in the sport? They're just bitter and playing politics to save face.

And, oh by the way, shame on all of you approaching this discussion with subjective speculation and argumentation, rather than coming in with an open-mind and willingness to learn.

LOL

Can't make up this level of hypocrisy.

And this post is on topic how and your only post in this thread, so you’ve added nothing of technical merit to this thread. I’ve showed real life examples, I’ve done some math for you all, and shared real life experience on race engine building. I’ve even shared a thesis from Ilmor Brixworth with enough dimmensions given and plan views shown that you can literally calculate combustion chamber and piston crown volumes for an engine that by almost all definitions is the same as these PU’s, and the rules outlining critical dimmensions needed to calculate all this.

Most real engineers haven’t complained and most teams just shrugged. Binotto is a real engineer but in his current role he’s a politician. The rest of these sources are inneundo from unverified sources known to be inacurrate and click bait sources by people who have showed time again to be inaccurate and don’t know what they’re talking about