GSC Power-Division Exhaust Valves – Subaru EJ20/EJ25 Turbo (32mm & 33mm) The GSC Power-Division Exhaust Valve range for Subaru EJ20 and EJ257 turbocharged engines offers maximum durability, flow, and performance in extreme conditions. Available in both standard 32mm and +1mm oversize 33mm diameters, these valves are engineered for high-horsepower, high-EGT applications where heat resistance and reliability are critical. Manufactured from advanced stainless and superalloy materials, these valves are swirl polished, back-cut, and micro-finished to reduce weight, improve airflow, and extend lifespan. Whether you’re chasing big boost or refining valve geometry, GSC valves are a trusted upgrade for any EJ build. Key Features Available in standard 32mm and oversize 33mm (+1mm) options Super Alloy version withstands up to 2000°F (ideal for extreme EGT conditions) Back-cut and swirl-polished heads for increased flow and reduced mass Micro-polished stems for smoother motion and less oil retention Modified 23-8N or Super Alloy exhaust valve material for high-heat tolerance Compatible with OEM or GSC valve locks Technical Specifications Valve Size Part # Material Head Diameter Stem Diameter Overall Length 32mm (Standard) GSC2015-8 Super Alloy 32.00 mm 6.0 mm 104.65 mm 33mm (+1mm Oversize) GSC2013-8 Modified 23-8N Stainless 33.00 mm 6.0 mm 104.25 mm Valve Design & Benefits Under-head dish machining for reduced weight Swirl-polished heads enhance flow without compromising strength Back-cut valve profile improves high-RPM performance Valve tips hardened or fused with a stelite wafer for wear resistance Adjusted valve tip lengths for proper valvetrain geometry and reduced lash setup time Optimised keeper groove height for balanced valve spring pressure and retainer fitment Vehicle Compatibility Subaru WRX – EJ20 / EJ205 / EJ207 Subaru WRX STI – EJ257 / EJ257B Subaru Forester XT / Liberty GT – EJ Turbo Platforms Note: It is recommended not to reuse valve locks in performance applications due to wear and groove deformation. Always inspect and replace during head service or rebuild.
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