The Mahle ECOBOOST Cylinder Head Bolt Set provides a complete replacement set of torque-to-yield head bolts for Mazda MZR and Ford Duratec engines commonly found in the NC Miata platform and popular 2.5L swap applications.

Whether you're replacing a head gasket, refreshing a stock engine, or completing a full performance build, fresh head bolts are critical to achieving proper clamping force and long-term reliability. Since factory head bolts are torque-to-yield fasteners, they should not be reused after removal.

Mahle is one of the most respected names in OEM engine sealing and hardware, making the kit an excellent choice for stock and mildly modified applications.

Why Replace Your Head Bolts?

Factory MZR and Duratec engines utilize torque-to-yield (TTY) fasteners that permanently stretch during installation. Reusing old bolts can result in:

• Inconsistent clamping force
• Head gasket sealing issues
• Coolant or combustion leakage
• Reduced reliability under high cylinder pressures
• 400whp Turbo/Supercharged Application