2026 Drama: Alleged engine loophole

[vorticism]

Martin is correct. A cylinder pressure sensor can only inform you of... cylinder pressure. Not the shape of the piston nor the head or anything inserted into it, nor stroke nor bore, etc. You can infer many things from it (hence its value) but couldn't rely too much on it as some sort of quasi 3D scanner peering into the combustion chamber, with a little arm that extends out with another smaller 3D scanner that inspects through the TJI chamber holes, with an even smaller tertiary 3D scanner that inspects any other chambers hidden behind microscopic orifices.

That said, without knowing how the FIA define GCR (distinct even from various definitions of CR) or what the testing procedures entail, much of this thread is akin to...



Which is to say: amusing.

[slinger]

If one where to spin the engine over with the mguk, with throttle valves fully open and no fuel injection, and then obtain a pressure reading for a set rpm. Then repeat at a higher rpm. Would readings be similar or wildly varied?
Then to repeat at higher temperature. Would they vary again? Being that we are just pumping air through the cylinder and compressing it.

[PlatinumZealot]

There is an interesting piece by Pat Symonds in Autosport this month on this topic. He says the compression ration will drop as the engine heats up, and says an engine with a 16:1 ratio, will be more like 15.2/15.3:1 at operating temperature. This is because the aluminum block expands by more than the connecting rod, ~0.3mm for the block and 0.05mm for the rod.

He then speculated that by putting a particular grade of steel liner into the cylinder block, the expansion for the block could be reduced to 0.05mm and by changing to a austenitic stainless steel for the rod, that could offer an expansion greater than the block.

He then moved on to the weight of the rod, and with a limit of 350 grams for the con rod, you could make one from stainless and still hit the weight target.

This is good because the yappers were saying that compression ratio increases with temperature not knowing what is expanding more than what lol and many people bought it! Goes to show that people go off of emotions rather than checking the facts.

[PlatinumZealot]

If one where to spin the engine over with the mguk, with throttle valves fully open and no fuel injection, and then obtain a pressure reading for a set rpm. Then repeat at a higher rpm. Would readings be similar or wildly varied?
Then to repeat at higher temperature. Would they vary again? Being that we are just pumping air through the cylinder and compressing it.

Many street car engines have mechanisms like that. Like BMW's valvetronic. The rules speak to geometric compression ratio, which have nothing to do with pressure in the cylinder.

[Martin Keene]

If one where to spin the engine over with the mguk, with throttle valves fully open and no fuel injection, and then obtain a pressure reading for a set rpm. Then repeat at a higher rpm. Would readings be similar or wildly varied?
Then to repeat at higher temperature. Would they vary again? Being that we are just pumping air through the cylinder and compressing it.

That’s an interesting question… it would change with temperature, I am not sure about rpm.

I think the answer to the rpm question would depend on volumetric efficiency and how well the engine can fill the cylinder at low rpm & high rpm, the spend with greater volumetric efficiency is likely to produce a higher pressure reading as the cylinder of fuller. I think…

[FrukostScones]

https://www.auto-motor-und-sport.de/for ... uswirkung/

finally it make sense, but not the FIA.

[bluechris]

Welcome to 2014

[FNTC]

Sandbags off and merc is 8 tenths ahead

[bluechris]

Sandbags off and merc is 8 tenths ahead

From pure driving skill and aero lol

[Badger]

Sandbags off and merc is 8 tenths ahead

From pure driving skill and aero lol

Definitely from aero. McLaren has the same engine and they were third today. Alpine and Williams look straight up slow. The chassis is the key. The engine advantage is nowhere near 8 tenths.

[bluechris]

Sandbags off and merc is 8 tenths ahead

From pure driving skill and aero lol

Definitely from aero. McLaren has the same engine and they were third today. Alpine and Williams look straight up slow. The chassis is the key. The engine advantage is nowhere near 8 tenths.

Well no, Mercedes had this engine for 3 full test sessions and McLaren got it for 3 fp's and you expect them to be there?

As for all the discussions that took place in this thread, you really guys now believe that this is only 10-12 HP? I don't think so from what i see from both MB's onboards.
The difference is so big that they have more downforce easily (its obvious when the car turns that isn't touching the curbs where all the others are on them and yet they turn faster).
It's game over and 2014 again as i see it.
Same as 2014 and onwards, more HP and barn door wings and championships are coming.

[bluechris]

In post race now in f1tv they say the same...

[ginobeppe]

how does mercedes recharge so much more even compared to mclaren?

[Chuckjr]

I think the reason the others with the Merc engine are not near as fast has a lot to do with the charge and deploy science Merc is using in their unit. It's why I think the test change in 7 or so races will do nothing to stop them. It's 2014 all over again.

[bluechris]

I think the reason the others with the Merc engine are not near as fast has a lot to do with the charge and deploy science Merc is using in their unit. It's why I think the test change in 7 or so races will do nothing to stop them. It's 2014 all over again.

McLaren has also completely different gear ratios which are very short, this maybe plays a role?