GSC +1mm Oversized Exhaust Valve – Mitsubishi Evo X 4B11T - GSC2023-01
GSC Power-Division’s +1mm oversized exhaust valve for the 4B11T engine features a 30mm head diameter, 5.5mm stem, and 105.85mm overall length. Designed for high-performance builds, this valve offers increased flow and durability under extreme heat and boost conditions.
Developed using advanced 3D modeling and simulation, GSC’s valve head design minimizes face distortion for improved sealing and consistent performance. Each prototype is flow-tested in its target application to ensure maximum efficiency and reliability.
Key Features:
- Swirl-polished head enhances airflow across the valve surface
- Back-cut profile reduces weight, supporting higher RPM and aggressive cam profiles without raising seat pressure
- Micro-polished stem minimizes oil retention and drag for smoother valve movement
- Exhaust valves made from modified 23-8N stainless for superior heat resistance and long-term durability
- Valve tips are either hardened or fused with stelite wafer, matched within 5 Rockwell C of the rocker or tappet for reduced wear
- Tip heights are optimized to reduce valve tipping and simplify lash setup
- Keeper grooves are precision-tuned to balance spring pressures and reduce the need for shims
- Compatible with OEM keepers/locks or GSC’s upgraded options—reusing old locks is not recommended for high-performance applications
Fitment:
- 2008–2015 Mitsubishi Lancer Evolution X GSR
- 2008–2015 Mitsubishi Lancer Evolution X MR
- 2008–2015 Mitsubishi Lancer Evolution X Final Edition
- 2008–2015 Mitsubishi Lancer Evolution X SE (Special Edition)
- 2008–2015 Mitsubishi Lancer Evolution X FQ Series (UK models)
CA Residents: WARNING: Cancer and Reproductive Harm www.P65Warnings.ca.gov
