Cosworth Big Valve Cylinder heads for the Dual AVCS 2008 STI EJ257B engine. Machine Ported for maximum accuracy and performance, complete with larger (+1mm) valves and dual valve springs for maximum flow. Cosworth Big Valve Cylinder heads are the key to high power and unlocking the performance potential in your Subaru engine.
Specification:
- Set CNC Ported/Machined finish port
- Set New Castings
- Set Hand blended finish work
- Set Intake 13.63% (average) 19.38% (max) increased flow
- Set Exhaust 31.44%(average) 37.78% (max) increased flow
- Set 4-angle Inlet Valve job
- Set 3-angle & radius Exhaust Valve job
- Set Valves are lapped
- Set Back-Cut Inlet Valves
- Set Heads are Ultra Sonic cleaned prior to assembly
- Set Heads are Serialized and sport a machined Cosworth logo
- Set +1mm Stainless Steel Intake Valves (1800 degrees max.)
- Set +1mm Inconel Exhaust Valves (2400 degrees max.)
- Set Performance Valve Springs
- Set Titanium Retainers
- Set Hardened Steel Spring Platforms
- Set Knife edged ports
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