The FIA has launched an e-vote primarily centred on a proposed change to the assessment of the power unit compression ratio in running condition.

Over recent weeks and months, the FIA and the Power Unit Manufacturers have collaboratively developed a methodology to quantify how the compression ratio changes from ambient to operating conditions.

Following validation of this approach, a proposal has been submitted whereby, from 1 August 2026, compliance with the compression ratio limit must be demonstrated not only at ambient conditions, but also at a representative operating temperature of 130 degrees C.

The vote has been submitted to the Power Unit Manufacturers, and its outcome is expected within the next 10 days and will be communicated in due course. As with all Formula 1 regulatory changes, any amendment remains subject to final approval by the FIA World Motor Sport Council.

Note: 1 August is just after the Hungarian Grand Prix, the 13th round of the 2026 season.

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READERS COMMENTS

1. Posted by NS Biker, 26/02/2026 0:07 (moderated by an Adminstrator, 26/02/2026 9:33)

"The irony of all this ruminating over ambient and elevated temperatures for determining the "static" compression ratio (CR) is pretty laughable.
Yes, the crank arms and connecting rods (and piston) will expand (raise) the position of the piston at TDC and at a bit less at BDC. The stroke would increase by the expansion of the crank arm.
The fly in the ointment is that the aluminium alloy block will expand double what the steel or ferrous components do to actually reduce the static CR.
The complexity of measuring the static CR at an elevated and controlled temperature will likely be enough that the whole idea will get binned.
There is little to be gained by doing it at 110 C. The elevated temperature number will (should) always be lower than an ambient temp measurement. Unless someone has introduced some funky super expanding materials or a hidden thermally triggered chamber volume adjusting device. Nah ... they wouldn't do that.??
There was talk about a hot and running CR measurement. Good luck with that. The number of variables goes exponential. Rod stretch, turbo boost level, valve timing, exhaust and inlet pulsation, engine revs and a further bunch of stuff that I am not privy to.
But, ya have to admit, it is all entertaining.
"

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2. Posted by NS Biker, 26/02/2026 0:01 (moderated by an Adminstrator, 26/02/2026 9:33)

"This comment was removed by an administrator as it was judged to have broken the site's posting rules and etiquette."

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3. Posted by Dirt, 19/02/2026 10:37

"@Simon: There could also be innovation with the connecting rods and crank shaft. Most assuredly neither is made from zinc. ;) A few things I've seen suggest 3D printing and engineered stretch under G load are also a possibility "

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4. Posted by Simon in Adelaide, 19/02/2026 3:07

"Just for a bit of amusement and discussion with those who know more than me (not difficult) :)

Most usual metals have a coefficient of expansion in the range 10-14 x 10^-6 per degree degree C, the exceptions are Plutonium (19.8), Sodium (39) and Zinc (19); I don't see them using Plutonium and Sodium is unstable so that leaves Zinc.

The proposed test temperature rise is 110C for all manufacturers not just Mercedes so those already at 16:1 compression ratio at 20C will need to change their conrods unless there is an increase in the volume of the combustion chamber that offsets the increase in length of the conrod.

The difference of say 5-7x10^-4 over say 150 mm conrod is just 0.075-0.010 mm.

I fail to see how a change of 1/100th of a millimetre could change the compression ratio from 16:1 to 18:1

So where have I gone wrong?

"

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5. Posted by Superbird70, 18/02/2026 19:50

"Who will be surprised when Mercedes sells its stake to Stellantis and just ditches this clown show? The reward for innovation in a world of participation trophies."

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6. Posted by ClarkwasGod, 18/02/2026 15:05 (moderated by an Adminstrator, 26/02/2026 9:33)

"It's a sad day that one engine supplier's innovative design is likely to be snuffed out just because other makers didn't think about it. Were the DFV to be introduced now, can you imagine the outcry from all the other teams "Our engines aren't powerful enough! It's not fair! Ban the Ford DFV!"
Just another factor dumbing down what is supposed to be the pinnacle of motorsport.
I just hope Mercedes are able to transpose the supposed "trick" into their commercial engines and stick a very large finger up at the other makers."

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7. Posted by Redphyve, 18/02/2026 14:25 (moderated by an Adminstrator, 26/02/2026 9:33)

"The levelling of the playing field by eliminating innovation continues apace. |I remember how Audi were banned in America and Europe with their cars many years ago, simply because they innovated and came up with solutions and engineering that led their cars to dominate their respective series. So they were banned because the opposition couldn't catch-up and the ruling bodies didn't want a tech war that would lead to increased spending and budgets and manufacturers dropping out.

Sad really."

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FIA to hold e-vote over change to engine regulations

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