F1's five power unit manufacturers are set to vote on a proposed tweak to how engine compression ratios are measured, which could come into force over the summer break. The 2026 power unit regulations prescribe an engine compression ratio of 16:1, down from 18:1 last year.
That compression ratio has always been measured at ambient temperature when the engine isn't running, so it doesn't account for thermal expansion during operation. The proposed change aims to address this measurement discrepancy.