FIA tightens 2026 engine rules to close thermal expansion loophole

THE FIA has delivered its verdict on the controversial 2026 engine compression ratio debate, confirming that revised wording will be introduced ahead of the summer, with implementation expected from June.

- JEHRAN NAIDOO

Following an electronic vote among manufacturers, the FIA has opted to tighten how the 16:1 compression limit is policed, closing what rivals believed was a potential loophole before the new regulation cycle fully beds in. Under the original 2026 technical regulations, the maximum permitted compression ratio of 16:1 was measured only at ambient temperature. In simple terms, engines were tested cold.

The concern raised by several manufacturers was that this left room for creative engineering solutions: an engine could legally comply with the 16:1 limit during scrutineering, but once at operating temperature, thermal expansion characteristics inside the combustion chamber could effectively alter the ratio under race conditions.

The revised wording changes that. From June onward, compliance will not only consider ambient checks but also account for behaviour at operating temperature, ensuring the 16:1 ceiling is respected in realistic race conditions.