Lt_Boards wrote: ↑23 Feb 2026, 00:41
- what conditions are the 1.6L capacity measured?
- Must this 1.6L limit be maintained at all times during normal operating conditions?
- How is this policed?
...
How can the 1.6L be so well controlled...
The FIA define cubic capacity as the swept volume of the pistons i.e. the volume encapsulated by the bore and the two most distant positions of the piston face. We don't, afaik, know how the FIA measures this, or when they inspect it. It is potentially easy to measure, as all you need to do is measure any fixed point upon the piston crown through its full travel. The size of the combustion chamber volume is not regulated directly but the spec GCR limits its minimum volume to around 18cc. Which means the total closed capacities of the engines are around 1.7l minimum.
To say it in a more confusing way: the "cubic capacity" is dictated by the spec bore diameter & cylinder count, while the cubic capacity is defined by the geometric compression ratio.
I would consider swept volume as displacement in the true sense of that term, not necessarily as capacity--regular terms in the ICE world often have multiple connotations and can be considered colloquialisms. There may even be translation artifacts between languages.
The question of how the ~1.7 liter and 108cc closed capacities i.e. the large and small parts of the GC ratio are potentially measured is the more prescient question in regards to the recent rumors.