Thanks. I think it’s fair to expect me to review the rules to find this vs. asking you to specify where it spells this out. I just spent some time trying to find where exactly in the rules this is defined. I understand it may not be worded exactly that way. I unfortunately can’t find anything that limits the only moving items in the cylinder (and by extension the combustion chamber) to be the piston and valves). If you (or anyone else) have the reference handy, I would appreciate it.PlatinumZealot wrote: ↑29 Dec 2025, 04:48The regulations say the only moving parts allowed in the cylinder are the pistons, and the intake and exhaust valves.
5.3.7 In a Cylinder Head, only inserts approved by the FIA Technical Department will be allowed.
The total volume of the inserts listed in a. to c. below cannot be more than 3% of the total
volume of each Cylinder Head and these must be confined to:
a. Conventional valve seat inserts
b. Conventional valve guide inserts
c. An insert concentric to the spark plug axis with a maximum outside diameter of 15mm
An additional allowance of 1% of the total volume of each cylinder head is permitted for
inserts other than those mentioned above, but none of these inserts can be exposed to the
combustion.
As I mentioned in my post (new bold by me)...
We can disagree on how much freedom exists here. Is not this entire thread about trying to understand how this might be done within the current rules? If a design is otherwise legal, why not approve it? But yes, FIA might not approve a specific design, even one that might be otherwise legal. Or maybe they might approve it!
Displacement seems to be defined by swept volume of cylinders. Which should be generally static and not variable. Combustion chamber size is undefined outside of the compression ratio rule which may (or may not) be an area for interpretation. For example, the compression ratio can't be higher than 16:1. Might you create a variable volume combustion chamber that allows for a lower compression ratio (not that you would want to do this). It sounds like maybe you could? The question is... can you go higher than 16:1 in some conditions if this is only measured (and you ensure it is legal/16:1) at ambient temperature (whatever that means).
It's all about sharing ideas (even if crazy) and learning things. We all have to think out of the box to explore where exploitable gaps exist in the rules. And some of those ideas might be very dumb or illegal in ways I haven't seen yet.Correct, the crankcase is limited only to iron or aluminium alloys (C15.7.Tommy Cookers wrote: ↑29 Dec 2025, 21:35every alloy doesn't have its code and isn't precisely defined
only in uses outside the PU perimeter are the alloys restricted (and iron-based alloys are unrestricted anyway)
inside the PU perimeter (apart from the piston etc) there is no such restriction
ie the cars can use any alloy ie an alloy made to the team's design or choice
the con-rods can be any iron-based or any titanium-based alloy and the crankshaft can be any iron-based alloy
(eg by iron-based the rules mean only that iron must be the biggest single ingredient)
so a steel or other iron-based engine block is possible ie 6 ppm/deg F expansion
for the rods established iron-based alloys (and mandated iron-based piston alloy) will give 9 ppm
these will do the '16-18 trick' (as I said a week ago)
the crank & rods & piston are taller and hotter and more expansive than the block
about a million British motorcycles had Al alloy rods and iron cylinders - so did the same 'trick'
. So too can the cylinder heads and cam covers be made of iron based alloys. Developing an all-steel engine would not be an overnight thing, so finding out that a competitor did could cause some worry. Yours is the best case I've seen in favor of the TE alteration of CR rumor.2026 is a new engine formula, so it would be useful to address the 2026 regulations, not the 2024, which is no longer valid.Richard C wrote: ↑30 Dec 2025, 01:28As I mentioned in my post (new bold by me)...We can disagree on how much freedom exists here. Is not this entire thread about trying to understand how this might be done within the current rules? If a design is otherwise legal, why not approve it? But yes, FIA might not approve a specific design, even one that might be otherwise legal. Or maybe they might approve it!
I also wanted to provide a more recent link for the regulations. The prior link is over a year old and out of date. I think there are differences. My earlier post is based off that 2024 document, so there might be something in the newer document that invalidates some of my thoughts. I haven't looked through deeply yet. I only noticed after posting that the document was old and out of date.
One easy thing to point out is that the June 24th 2024 version does not include the text regarding measuring compression ratio while the October 12th 2025 document does. Also, given the recent edits are included in pink and the call out for ambient temperature is not in pink, I assume a version between June 2024 and October 2025 included the "ambient temperature" edit and then this newest one includes more specifics.
https://www.fia.com/system/files/docume ... 2-10_0.pdf
Richard
Maybe poor explanation on my end. The prior document (technical specification) that was linked was dated 2024, but was for the 2026 regulations. They have changed some since then. The link I provided was for the most recent 2026 regulations. And that document will eventually be replaced at some point as well by a newer revision. I was not calling out specifics from the previous era technical specifications.
The guy didn't say it is bollocks. He said they could use a layered cylinder head to create bulging into the combustion chamber at operating temperature. What did you take from it?atanatizante wrote: ↑30 Dec 2025, 12:45This topic is a load of bollocks! And I'm not the one who is telling this thing but rather real enginners with lots of expertize in this area: (use CC to translate)
I did not hear him saying this topic is a load of bollocks... Instead he suggested an other way to do it, which might make sense.atanatizante wrote: ↑30 Dec 2025, 12:45This topic is a load of bollocks! And I'm not the one who is telling this thing but rather real enginners with lots of expertize in this area: (use CC to translate)
