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CNC Ported Big Valve Cylinder Heads

Cosworth has eliminated assembled engine components from their product line including their popular line of big valve cylinder heads. We have replicated the Cosworth heads as closely as we can by using all Cosworth valvetrain components and machining processes but head castings are our own 5-axis CNC heads. As per the original Cosworth specification, these heads feature +1mm Cosworth valves, Cosworth's ultra high RPM dual valve spring and retainer set, and Cosworth S2 cams, Valve seats are machined on Newen CNC valve seat cutting equipment as were Cosworth's original versions.

Fully assembled from all new components. Valve clearances are set and heads are ready for installation.

Currently heads are made to order with a 6 week delivery time.

Manufacturer: RalliSpec


  • Subaru WRX STI MY15-17 (EJ257)
  • Subaru Impreza STI MY04-14 (EJ257)
Part No. Description Application Price Ea. Add to Cart
RCH-C2504 RalliSpec Cosworth Spec Big Valve B25 Cylinder Head Set w/ Cams MY04-06 $5995.00
RCH-C2507 RalliSpec Cosworth Spec Big Valve V25B Cylinder Head Set w/ Cams MY07 $5995.00
RCH-C2508 RalliSpec Cosworth Spec Big Valve W25 Cylinder Head Set w/ Cams MY08-17 $5995.00