FIA clamps down on F1 engines as hot-temperature test rule sparks Mercedes row

March 12, 2026 Aksel Kryhlmand

Tougher engine checks coming in 2026

Formula 1’s governing body, the FIA, is preparing to tighten scrutiny of engine compliance starting in June 2026, with new checks focusing on how power units behave once they reach full operating temperatures.

According to ESPN, the governing body plans to revise its inspection procedures so engines must remain within the 16:1 compression ratio limit even when tested at higher temperatures.

The change comes after growing discussion among teams and engineers about whether the current technical checks fully reflect the conditions engines face during race running.

Focus on compression ratio testing

Under the revised procedure, teams will be required to prove their engines remain compliant with the 16:1 compression ratio limit when tested under hotter conditions.

Engine compression ratios can shift slightly as internal components heat up and expand, something that has prompted questions from rival teams about whether certain designs might behave differently once a power unit is fully warmed during competition.

According to ESPN, critics have suggested that the Mercedes engine concept could potentially exceed the threshold when hot, raising concerns that current inspection methods may leave room for interpretation.

Mercedes has rejected those suggestions and denied the claims.

FIA aims to remove grey areas in testing

Although the allegations remain disputed, the FIA’s move appears intended to remove uncertainty surrounding how engine legality is measured.

By adjusting the testing conditions and introducing higher temperature checks, the governing body is attempting to eliminate potential grey areas that teams could theoretically exploit.

Officials believe the updated process will create clearer technical standards for every manufacturer competing in Formula 1.

New rule could reshape engine development

The rule change may affect more than one team, because every engine supplier will now have to demonstrate compliance under stricter thermal conditions.

That could become particularly important as Formula 1 moves toward the broader technical changes planned for the 2026 regulations era, when engine performance margins are expected to be extremely tight.

According to ESPN, the updated test procedures signal that the FIA intends to monitor performance gains tied to testing conditions more closely as it seeks to maintain competitive balance across the championship.

Sources: ESPN