Fire Ring Upgrade - Block Machining (EJ & FA)

CJM Fire Ring Upgrade

The CJM Fire Ring Upgrade provides the ultimate head sealing solution for high-boost Subaru engines. A counterbore step is precisely machined around each cylinder bore, allowing specially sized fire rings to seat perfectly between the machined area and the head gasket bore. Once installed and torqued, the rings create a tight compression seal between the cylinder head and block, preventing combustion leakage under extreme pressures.

CJM machinists carefully cut each counterbore to exact depth and tolerance, ensuring the fire ring stands slightly proud above the deck surface to achieve a superior seal when clamped. The fire rings are manufactured from a proprietary high-strength alloy and heat-treated for exceptional durability and resilience.

It is highly recommended to pair this upgrade with CJM’s 14mm high-strength head stud upgrade to ensure maximum clamping force and sealing integrity under extreme conditions.