GSC Power-Division Intake/Exhaust Valves - Evo X



Fits these Applications:
2008-2015 Mitsubishi Lancer Evolution X

GSC Power-Division valves are available as a set of 8 intake valves or exhaust valves. Standard and SUPER ALLOY options are available for the 4B11 Evo X models.

For those running high horsepower, high EGT set ups that need a valve that will last in 2000F conditions. The Super Alloy Exhaust valves have Chrome polished stems to create a smooth, durable finish for added life and better lubricity especially when paired with the GSC Manganese bronze valve guides. Strength, heat resistance and performance are engineered into every valve. Under head dish is maximized for weight savings while swirl polished and backcut heads promote better air flow without sacrificing durability.

Standard Valve Features:
When creating our new valve line we set out to create the best performance longest lasting valves available to the aftermarket. Using advanced 3D design and simulation programs we have created a stronger and higher flowing valve head design. We flow test prototype valve heads in the specific applications to make sure we have the highest flowing valve head available on the market today. With the materials used we have less valve distortion at the face than any of the tested designs. Less distortion allows or better sealing under extreme conditions and more consistent performance threw the life of the valve. GSC Power-Division's new valves are sure to become the industries standard for sport compact performance valves.


  • Swirl polished heads for smoother air flow over the valve
  • Back cut to reduce valve weight for higher rpm, higher boost pressure and allow for more aggressive cam profiles without increasing valve spring seat pressures
  • Valve stems are micropolished to allow for less oil retention on the stem which creates less drag on the stem to guide for a smoother motion.
  • Intake valves are a modified 21-4n stainless and Exhausts are a modified 23-8n stainless material for high heat capacity while maintaining longevity
  • Valve tips are either hardened or have a stelite wafer tip fused so that the tip is within 5 Rockwell C of the rocker or valve tappet for extended life and less wear
  • Valve tip lengths. We have taken extra time to adjust tip heights on the applications to require less tipping of the valve to maintain proper tip height for proper valve train geometry, and to cut down on install times when setting valve lash
  • We have also adjusted the Keeper grove to properly balance intake and exhaust spring pressures to reduce the use of valve spring shims and maximize performance from our spring and retainer kits
  • Valves will work with an OEM keeper/lock or when available our upgrade keeper/lock. It's not mandatory but it is suggested that any valve lock not be reused on performance applications do to material grooving

GSC Power-Division 4B11 Evo X Intake & Exhaust Valves

Part Number Intake/Exhaust Valve Type Size Quantity
GSC2025-8 Exhaust SUPER ALLOY STD / 29mm Set of 8
GSC2025-01 Exhaust SUPER ALLOY STD / 29mm Single
GSC2027-8 Exhaust SUPER ALLOY +1mm / 30mm Set of 8
GSC2027-01 Exhaust SUPER ALLOY +1mm / 30mm Single
GSC2021-8 Exhaust Standard STD/29mm Set of 8
GSC2021 Exhaust Standard STD/29mm Single
GSC2023-8 Exhaust Standard +1mm / 30mm Set of 8
GSC2023 Exhaust Standard +1mm / 30mm Single
GSC2022-8 Intake Standard STD/35mm Set of 8
GSC2022 Intake Standard STD/35mm Single
GSC2024-8 Intake Standard +1mm/36mm Set of 8
GSC2024 Intake Standard +1mm/36mm Single

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