2026 Drama: Alleged engine loophole

[Hoffman900]

For those wondering about rod stretch, the rods usually stretch slightly at TDC during the exhaust cycle, when a returning negative pressure wave in the exhaust helps drop the cylinder pressure below 1 atmosphere during the valve overlap period. Obviously, material grows with head as well, and that’s a big part of it.

For a typical V8 drag race engine, that runs, say 9000rpm:

Aluminum rods: 1.3-1.5mm cold p-h clearance
Steel rods: 1mm-ish piston to head

Both get you near 0.1mm running clearance, with a 100mm + bore, 90mm + stroke, at those kind of rpm’s and piston weights. So their running compression will be the same, but obviously will measure different cold. Most builders who don’t have the sophistication to do live firing FEA analysis, just simply keep closing up the piston - head clearance and on tear down check. Usually when you see start seeing clean spots on both, you know you’re there. That’s how builders have been doing it for decades.

[AR3-GP]

I think there is some interesting things with their PU. There would be no reason to be defensive otherwise.

[Hoffman900]

I think there is some interesting things with their PU. There would be no reason to be defensive otherwise.

I don’t get a defensive tone, I get “you people are idiots, this is something we’ve always done, and just because you didn’t know / understand it, doesn’t make it a story, so stop asking me about it”

Wait until Nugnes finds out the secret to going fast is to first fill the fuel tank.

[catent]

Second combustion chamber Nugnes is just vomiting nonsense, he has nothing of value to add. I suspect "Autoracer" is of similar credibility. Italian F1 media will invent their own stories or run with unsubstantiated rumours.

I am starting to doubt the validity of this entire story TBH. If it's not thermal expansion, and that seems increasingly unlikely given what we know about the materials allowed, what can it really be that wouldn't show up at ambient temperatures? Someone obviously queried the FIA on the test, hence the clarified formulation of the rule to say "at ambient temperatures", but maybe that's where the real story ends and the rumours of insane tricks begin.

Then you'd suspect incorrectly. Autoracer is a quality reporting outlet and absolutely will report the truth, even if it is inconvenient for Ferrari.

Are their reporters Ferrari fans? Absolutely - and the same can be said for British media reporters vis-a-vis McLaren, Mercedes fandom - but they work with integrity and are more than willing to hold Ferrari accountable for their missteps. They are not a narrative over facts platform. Not even close.

[AR3-GP]

Conventionally a cylinder block would be made of aluminium and a connecting rod of titanium. Approximating, the block temperature would be at around cooling water temperature, say 125C and the rod at around oil temperature, say 145C. At these temperatures the block may grow around 0.3mm and the rod around 0.13mm, meaning that the cylinder head moves away from the piston thereby dropping the compression ratio. With these materials and temperatures, the compression ratio, designed to be 16:1 at room temperature would drop to around 15.2:1, with a consequential drop in theoretical performance.

Now, if one was to make the block out of a material such as Invar, a steel designed to have low thermal expansion, and the rod was made from an austenitic stainless steel, we find that the block now grows by around 0.05mm and the rod by 0.3mm. A reversal of the situation with conventional materials and consequentially an increase in compression ratio. If the ambient compression ratio was set at 16:1, such a design could lead to an operating compression ratio of over 17:1.

https://www.autosport.com/f1/news/the-q ... /10791892/

Pat Symonds says its fairly simple, contrary to the protest here that it's impossible...

Someone correct me if I am wrong:
Most of the methods I read here and elsewhere does not make sense imho, as to increase compression ratio you need to change the travel of the piston not its volume.
The methods I saw all change the volume of the chamber in a constant way. Those methods would only change the compression if the volume changes back to the lower state when the compression begins and the volume shrinks at the time the compression is the highest.

Correct.

And rod stretch isn’t going to do it either, everyone has been running net zero piston-head clearances for decades in all forms of racing. It makes the most power (we’re talking 300-500rpm ceilings before the stretch actually causes damage). They were already at the limit.

From cold to hot, most racing engines see .1-.3 or so growth in compression ratio by gaps closing up from rod stretch and thermal expansion.

F1’s rules called for measurement at cold. So of course everyone is higher than this in practice.

[Tommy Cookers]

Now, if one was to make the block out of a material such as Invar, a steel designed to have low thermal expansion, and the rod was made from an austenitic stainless steel, we find that the block now grows by around 0.05mm and the rod by 0.3mm. A reversal of the situation with conventional materials and consequentially an increase in compression ratio. If the ambient compression ratio was set at 16:1, such a design could lead to an operating compression ratio of over 17:1.

https://www.autosport.com/f1/news/the-q ... /10791892/
Pat Symonds says its fairly simple, contrary to the protest here that it's impossible...

Autosport are saying EXACTLY what I wrote weeks ago (except for their mistakes)
I said you need ....
a hardened invar (ArcelorMittal) block/head - this is invar with additions to make it harder and stronger than Invar
an austenitic iron (aka steel) con-rod - (not austenitic STAINLESS steel- that isn't hardenable eg it's used for teaspoons)

the rod lengthens when hot (more than block/head) - so intrudes into the combustion chamber and reduces its volume
the CR has increased in almost exact proportion to the decrease in chamber volume


EDIT imo some posters aren't allowing for the volume expansion of the combustion chamber (when predicting hot CR)


yes I have messed up the quote-editing (that's why it looks like AR3 wrote this)

[Hoffman900]

Conventionally a cylinder block would be made of aluminium and a connecting rod of titanium. Approximating, the block temperature would be at around cooling water temperature, say 125C and the rod at around oil temperature, say 145C. At these temperatures the block may grow around 0.3mm and the rod around 0.13mm, meaning that the cylinder head moves away from the piston thereby dropping the compression ratio. With these materials and temperatures, the compression ratio, designed to be 16:1 at room temperature would drop to around 15.2:1, with a consequential drop in theoretical performance.

Now, if one was to make the block out of a material such as Invar, a steel designed to have low thermal expansion, and the rod was made from an austenitic stainless steel, we find that the block now grows by around 0.05mm and the rod by 0.3mm. A reversal of the situation with conventional materials and consequentially an increase in compression ratio. If the ambient compression ratio was set at 16:1, such a design could lead to an operating compression ratio of over 17:1.

https://www.autosport.com/f1/news/the-q ... /10791892/

Pat Symonds says its fairly simple, contrary to the protest here that it's impossible...

Someone correct me if I am wrong:
Most of the methods I read here and elsewhere does not make sense imho, as to increase compression ratio you need to change the travel of the piston not its volume.
The methods I saw all change the volume of the chamber in a constant way. Those methods would only change the compression if the volume changes back to the lower state when the compression begins and the volume shrinks at the time the compression is the highest.

Correct.

And rod stretch isn’t going to do it either, everyone has been running net zero piston-head clearances for decades in all forms of racing. It makes the most power (we’re talking 300-500rpm ceilings before the stretch actually causes damage). They were already at the limit.

From cold to hot, most racing engines see .1-.3 or so growth in compression ratio by gaps closing up from rod stretch and thermal expansion.

F1’s rules called for measurement at cold. So of course everyone is higher than this in practice.

V8 drag race and circle track builders set P-H around .040in (1mm) with steel rods which in practice is near zero Piston to Head clearance at redline. This isn’t out of the realm at all.

For a typical racing US domestic V8 with a 4.25in bore, 64cc chambers, and a 10cc dome, that’s a change from to 12:1 to 13.9:1.

This has been a “thing” for decades in race engine building. No fancy degrees or materials needed and certaintly not an industry secret.

[dialtone]

I don't think Binotto is unaware of any of this, he built engines for ages. I think his concerns is that the rules say the CR has to be 1:16 at all times in his interpretation. The ambient temperature was added too late and still just on the measurement side, not on the compliance side.

[Sbrillo88]

So, looks like that FIA and all teams haven't found an agreement on the story and for now they will not change anything soon.
From L'Equipe:

"It seems that they have only succeeded in complicating matters," the journalist wrote. "According to our information, a new measurement system should soon be implemented to measure the compression ratio when the engine is hot, but the timeline remains unclear."
Ferret added that, in the meantime, the risk of a contentious season opener remains very real. "The spectre of a chaotic and contentious start to the season is looming," he noted, pointing in particular to Aston Martin and Honda’s frustration with the current interpretation of the rules.
"It is easy to imagine that in Australia, one or more teams will lodge a protest, disrupting the smooth start to the season the sport had hoped for with these new regulations."
Honda, whose engines will power Aston Martin from 2026, reiterated its preference for clarity. HRC president Koji Watanabe said: "There is a lot of room for interpretation, and that’s part of it. But it’s up to the FIA to determine what is permissible. We will always consult the FIA on regulatory matters."

[bluechris]

So, looks like that FIA and all teams haven't found an agreement on the story and for now they will not change anything soon.
From L'Equipe:

"It seems that they have only succeeded in complicating matters," the journalist wrote. "According to our information, a new measurement system should soon be implemented to measure the compression ratio when the engine is hot, but the timeline remains unclear."
Ferret added that, in the meantime, the risk of a contentious season opener remains very real. "The spectre of a chaotic and contentious start to the season is looming," he noted, pointing in particular to Aston Martin and Honda’s frustration with the current interpretation of the rules.
"It is easy to imagine that in Australia, one or more teams will lodge a protest, disrupting the smooth start to the season the sport had hoped for with these new regulations."
Honda, whose engines will power Aston Martin from 2026, reiterated its preference for clarity. HRC president Koji Watanabe said: "There is a lot of room for interpretation, and that’s part of it. But it’s up to the FIA to determine what is permissible. We will always consult the FIA on regulatory matters."

We all knew that from the beginning, Darth Toto Rules.

[dren]

So, looks like that FIA and all teams haven't found an agreement on the story and for now they will not change anything soon.
From L'Equipe:

"It seems that they have only succeeded in complicating matters," the journalist wrote. "According to our information, a new measurement system should soon be implemented to measure the compression ratio when the engine is hot, but the timeline remains unclear."
Ferret added that, in the meantime, the risk of a contentious season opener remains very real. "The spectre of a chaotic and contentious start to the season is looming," he noted, pointing in particular to Aston Martin and Honda’s frustration with the current interpretation of the rules.
"It is easy to imagine that in Australia, one or more teams will lodge a protest, disrupting the smooth start to the season the sport had hoped for with these new regulations."
Honda, whose engines will power Aston Martin from 2026, reiterated its preference for clarity. HRC president Koji Watanabe said: "There is a lot of room for interpretation, and that’s part of it. But it’s up to the FIA to determine what is permissible. We will always consult the FIA on regulatory matters."

We all knew that from the beginning, Darth Toto Rules.

Not when facing Massie lol

[dialtone]

So, looks like that FIA and all teams haven't found an agreement on the story and for now they will not change anything soon.
From L'Equipe:

"It seems that they have only succeeded in complicating matters," the journalist wrote. "According to our information, a new measurement system should soon be implemented to measure the compression ratio when the engine is hot, but the timeline remains unclear."
Ferret added that, in the meantime, the risk of a contentious season opener remains very real. "The spectre of a chaotic and contentious start to the season is looming," he noted, pointing in particular to Aston Martin and Honda’s frustration with the current interpretation of the rules.
"It is easy to imagine that in Australia, one or more teams will lodge a protest, disrupting the smooth start to the season the sport had hoped for with these new regulations."
Honda, whose engines will power Aston Martin from 2026, reiterated its preference for clarity. HRC president Koji Watanabe said: "There is a lot of room for interpretation, and that’s part of it. But it’s up to the FIA to determine what is permissible. We will always consult the FIA on regulatory matters."

Binotto has already said they’ll sue in Australia as he thinks this is worth up to 0.4s per lap and was done improperly.