FIA Settles Compression Ratio Dispute Ahead of 2026 Campaign

The FIA has reached a resolution on the geometric compression ratio matter that sparked debate involving Mercedes. The ruling comes as Formula 1 prepares for the 2026 season.

As the paddock gears up for the 2026 F1 season, motorsport's governing body has finally put to bed the geometric compression ratio controversy that has dominated recent discussions. The FIA's announcement regarding this technical matter follows the high-profile dispute that emerged around Mercedes' engine specifications.

The resolution of this issue represents a significant milestone for the sport as teams prepare their power units and technical packages for the year ahead. With the ruling now in place, teams can move forward with clarity on the regulations governing engine compression ratios heading into 2026.

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Full Regulation Text

Technical Regulations

Article C5.4.3

FIA Source

Geometric compression ratio limit

Chapter: C5

In Simple Terms

F1 engines have a limit on how much they can compress the air-fuel mixture inside each cylinder. No cylinder is allowed to have a compression ratio higher than 16.0, which means the mixture can be squeezed to no more than 16 times its original volume. Manufacturers measure this themselves following FIA guidelines.

Maximum compression ratio of 16.0 applies to every cylinder in the engine
Compression ratio measures how much the air-fuel mixture is squeezed before ignition
Each engine manufacturer is responsible for measuring and verifying their own compression ratio
Measurements must follow FIA-provided guidance to ensure standardization

Official FIA Text

No cylinder of the engine may have a geometric compression ratio higher than 16.0. The procedure to measure this value will be detailed by each PU Manufacturer according to FIA guidance.

compression ratioengine regulationscylindergeometric compressionengine limit

2026 Season Regulations

Technical Regulations

Article 2.2

FIA Source

2026 Power Unit Regulations

Chapter: Chapter II - Power Unit Changes

In Simple Terms

2026 brings major engine rule changes. The complex MGU-H is removed to cut costs and attract new manufacturers. To compensate, the MGU-K becomes much more powerful and the battery is bigger. The goal is simpler, more sustainable power units that are still cutting-edge.

MGU-H removed from power units
MGU-K power increased significantly
Larger energy store capacity
Aims to attract new manufacturers

Official FIA Text

For 2026, the power unit will comprise a 1.6 litre V6 turbocharged internal combustion engine with a significantly enhanced electrical component. The MGU-H will be removed. The electrical power output will increase substantially with a more powerful MGU-K and larger energy store.

power unit componentsnew manufacturerssustainability2026 regulationsMGU-HMGU-Kpower unitnew regulations

2026 Season Regulations

Technical Regulations

Article 1.2

FIA Source

Homologation dossier contents

Chapter: Appendix C5

In Simple Terms

Before a team can use a new power unit in F1, they need to submit a complete package of paperwork to the FIA. This package must list every major power unit component, all the smaller parts, and other required documents following a specific FIA template (FIA-F1-DOC-C047). Think of it as getting your engine approved before you can race.

Teams must document all Power Unit (PU) Elements - the major components like the engine, turbo, and MGU systems
A detailed list of Minor Parts must be included - smaller components that make up the power unit
All submissions must follow the official FIA-F1-DOC-C047 format and template
This homologation process is the approval system that ensures all power units meet F1 regulations