2026 Drama: Alleged engine loophole

[OBELIKS]

The FIA don't need to find it. Toto Wolff said his team would change the engine. They are not going to be dishonest about it and I believe them.

Unless the FIA knows whats up I am very reluctant to trust Wolff. Nothing is stopping Mercedes from running illegal engines as long as the FIA don't know whats illegal about them. I think we all know the FIA well enough.

Mercedes-Benz is one of the largest auto-manufacturers in the world. They don't think like this. It's a risk conscious business. They developed their tricking thinking the FIA approved it. When the FIA said no, they conceded to remove it. That's exactly how a large company like this would operate.

Yeah about that... Especially big companies like to bend things to their liking. Remember Dieselgate? It started in 2015 with VW and MB was one of the manufacturers caught cheating. Allegedly (not sure if the legal process is done).

[dans79]

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.

I covered this weeks ago in A different thread. Even if you cherry picked the perfect stainless with the highest coefficient of linear expansion, the rod would have to be heated to such a high temperature that you would like have all kinds of oil issues.

The fundamental issue is Pat and all of the press, are just pulling theories out of their backsides. None of them are based on reality, where a million really world factors and considerations need to be taken into account.

[Martin Keene]

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.

I covered this weeks ago in A different thread. Even if you cherry picked the perfect stainless with the highest coefficient of linear expansion, the rod would have to be heated to such a high temperature that you would like have all kinds of oil issues.

The fundamental issue is Pat and all of the press, are just pulling theories out of their backsides. None of them are based on reality, where a million really world factors and considerations need to be taken into account.

Pat Symonds started in engines, so I'd take anything he says over any other source that has been out there on this subject.

[AR3-GP]

I covered this weeks ago in A different thread. Even if you cherry picked the perfect stainless with the highest coefficient of linear expansion, the rod would have to be heated to such a high temperature that you would like have all kinds of oil issues.

The fundamental issue is Pat and all of the press, are just pulling theories out of their backsides. None of them are based on reality, where a million really world factors and considerations need to be taken into account.

Do you know who Pat Symonds is?

[Tommy Cookers]

A steel head expands less than an aluminum head. This is relevant for discussion surrounding the loss of compression ratio at operating temperature.....

How much length should this add? This is neglectable vs the length of the rods. The issue is the different expansion between the Al block and the rods as these are long.

the issue is in large part the volume expansion of the space within the head
ie if the cylinder expands like Al the cylinder's volume will expand relatively much more than the head's volume
is the cylinder the (coated) Al-alloy block or is it a 'wet' ferrous liner ?

[dans79]

I covered this weeks ago in A different thread. Even if you cherry picked the perfect stainless with the highest coefficient of linear expansion, the rod would have to be heated to such a high temperature that you would like have all kinds of oil issues.

The fundamental issue is Pat and all of the press, are just pulling theories out of their backsides. None of them are based on reality, where a million really world factors and considerations need to be taken into account.

Do you know who Pat Symonds is?

Yes I know exactly who he is!

[Tommy Cookers]

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.

I pointed out on this site and before Mr Symonds that ArcelorMittal will sell a material to do this block
it is what they call 'hardened invar' (not Invar which is a old invention belonging to another company))
AM's material has very low expansion and is strong and hard (unlike Invar)

[Tommy Cookers]

That rumor was apparently a cylinder head, which I still really struggle to see the benefit of.

A steel head expands less than an aluminum head. This is relevant for discussion surrounding the loss of compression ratio at operating temperature. A steel head can also sustain a higher operating temperature without losing its stiffness. Higher operating temperature means less cooling and more thermal efficiency.

a higher operating temperature may be undesirable eg if that causes detonation

but heat flow can be better because a steel head can be much thinner as steel is much stronger at temperature than Al
as F1 piston crowns are much thinner than conventional pistons
(such improved heat flow could in principle allow higher CR/ER)

[basti313]

A steel head expands less than an aluminum head. This is relevant for discussion surrounding the loss of compression ratio at operating temperature.....

How much length should this add? This is neglectable vs the length of the rods. The issue is the different expansion between the Al block and the rods as these are long.

the issue is in large part the volume expansion of the space within the head
ie if the cylinder expands like Al the cylinder's volume will expand relatively much more than the head's volume

So what does this mean? I still do not see where the relevance comes from. The volume gain in the head itself is still neglectable.

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.

How should a liner change the expansion? A liner will always move with what the block does, otherwise the liner or the whole engine is defective.

Honda in the past did not use liners. I do not know if Merc or Ferrari used liners.

but heat flow can be better because a steel head can be much thinner as steel is much stronger at temperature than Al

Not really. We are talking about at least a factor of 4-5 on heat conductivity. You can not make steal 4-5 times thinner.

[Martin Keene]

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.

I pointed out on this site and before Mr Symonds that ArcelorMittal will sell a material to do this block
it is what they call 'hardened invar' (not Invar which is a old invention belonging to another company))
AM's material has very low expansion and is strong and hard (unlike Invar)

Sorry, I hadn't seen your post, but funnily enough invar was the very material he mentioned for the block/liners.

How much length should this add? This is neglectable vs the length of the rods. The issue is the different expansion between the Al block and the rods as these are long.

the issue is in large part the volume expansion of the space within the head
ie if the cylinder expands like Al the cylinder's volume will expand relatively much more than the head's volume

So what does this mean? I still do not see where the relevance comes from. The volume gain in the head itself is still neglectable.

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.

How should a liner change the expansion? A liner will always move with what the block does, otherwise the liner or the whole engine is defective.

Honda in the past did not use liners. I do not know if Merc or Ferrari used liners.

but heat flow can be better because a steel head can be much thinner as steel is much stronger at temperature than Al

Not really. We are talking about at least a factor of 4-5 on heat conductivity. You can not make steal 4-5 times thinner.

There are different types of liner, wet liners and dry liners. Wet liners can move independently of the block, that is how the Rover K Series works for example, the head seals to the liner not the block.

[basti313]

On an F1 engine? But anyways, does not change the issue as it does not affect the distance from crank to head.

[Tommy Cookers]

what about the temperature effects on the distances on the x axis and the y axis ie the change in the cylinder area ?

with temperature change the swept volume will change and the unswept volume will change
by the same proportion only if the metals are identical throughout the engine
but in different proportions if eg the cylinder liner behaves like al alloy and the head is steel (or vice versa)

[basti313]

what about the temperature effects on the distances on the x axis and the y axis ie the change in the cylinder area ?

Neglectable.

but in different proportions if eg the cylinder liner behaves like al alloy and the head is steel (or vice versa)

No. There is nothing like a "dome" on a Hemi engine. The volume in the head is neglectable.

[Hoffman900]

what about the temperature effects on the distances on the x axis and the y axis ie the change in the cylinder area ?

with temperature change the swept volume will change and the unswept volume will change
by the same proportion only if the metals are identical throughout the engine
but in different proportions if eg the cylinder liner behaves like al alloy and the head is steel (or vice versa)

I have a lot of experience on wet liner engines and several posts on this are nonsense as it relates to F1 engines.

The only that that really happens on an aluminum head / block engine with wet liners and through steel bolts is clamping is a bit higher when hot. Using “strongerl bolts actually leads to failures as many with a Rover K series found when using stronger bolts sourced from ARP, resulting in distortions and cracked crank plates.

Chamber distortion is neglible, less you totally trash your valve seating / sealing. 250 bar or so cylinder pressure will find anyway through, seats and valves will burn up, service intervals would be trash, and efficiency would sink like a ship

[f1isgood]

It's likely that the other manufacturers have done work specifically to maintain a 16:1 compression ratio where it otherwise normally drop. It's just what they would do as engineers. Hodgkinson said everyone knows about thermal expansion and would be aiming for just under 16:1.

The huge story was that Mercedes went above 16:1.

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.