GSC Power-Division exhaust valves for the 4B11 Evo X. Exhaust valves are sold as a set of 8 or individually as needed. Choose the standard modified 23-8N stainless material or 2000°F Super Alloy. Available in the standard 29mm size or +1mm oversized. Valve stem diameter is 5.5mm, overall length is 105.85mm.
Vehicle Fitment:
Mitsubishi 4B11
2008-2015 Evolution X
GSC Exhaust Valves:
| Part Number: | Head Diameter Size: | Material: | Quantity: |
| GSC 2021-8 | STD Size (29mm) | 23-8N | Set of 8 |
| GSC 2021-01 | STD Size (29mm) | 23-8N | Single Valve |
| GSC 2023-8 | +1mm (30mm) | 23-8N | Set of 8 |
| GSC 2023-01 | +1mm (30mm) | 23-8N | Single Valve |
| GSC 2025-8 | STD Size (29mm) | Super Alloy | Set of 8 |
| GSC 2025-01 | STD Size (29mm) | Super Alloy | Single Valve |
| GSC 2027-8 | +1mm (30mm) | Super Alloy | Set of 8 |
| GSC 2027-01 | +1mm (30mm) | Super Alloy | Single Valve |
Super Alloy:
GSC Power-Division Super Alloy Exhaust Valves are for those running high horsepower, high EGT set ups that need a valve that will last in 2000°F 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 back cut heads promote better air flow without sacrificing durability.
More Info:
Using advanced 3D design and simulation software, GSC has created a stronger and higher flowing valve head design. GSC flow tests prototype valve heads in the specific applications to ensure the highest flowing valve head available on the market today. With the materials used, GSC offers less valve distortion at the face than any of the tested designs. Less distortion allows for better sealing under extreme conditions and more consistent performance throughout the life of the valve.
- 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 micro polished 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 – GSC takes 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
- GSC has also adjusted the keeper groove to properly balance intake and exhaust spring pressures to reduce the use of valve spring shims and maximize performance from GSC spring and retainer kits
- Valves will work with an OEM keeper/lock or, when available, GSC upgraded keeper/lock. It is not mandatory, but it is suggested, that any valve lock not be reused on performance applications due to material grooving
Pictured:
Photos are for reference.
| Select: | STD 29mm Set of 8 (GSC2021-8), STD 29mm Single Valve (GSC2021-01), +1 30mm Set of 8 (GSC2023-8), +1 30mm Single Valve (GSC2023-01), Super Alloy STD 29mm Set of 8 (GSC2025-8), Super Alloy STD 29mm Single Valve (GSC2025-01), Super Alloy +1 30mm Set of 8 (GSC2027-8), Super Alloy +1 30mm Single Valve (GSC2027-01) |
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