4B11T +1mm Intake Valve Set

The GSC Power Division 4B11T 21-4N Chrome Polished Intake Valve Set is engineered for performance enthusiasts seeking to maximize airflow in their Mitsubishi Lancer Evolution X (2008-2016) and Lancer Ralliart (2009-2014) models. These intake valves feature a 36mm head diameter, which is 1mm larger than stock, to significantly increase intake flow capacity and support builds up to 500+ horsepower. Constructed from a high-nickel alloy 21-4N stainless steel, they are built to withstand high boost and temperatures up to 1600°F, making them ideal for turbocharged applications. Installation requires professional attention. Specifically, valve seat machining of 0.5-1.0mm for the 36mm head using a multi-angle cutter is necessary to achieve a proper interference fit. It is also recommended to inspect valve guides for wear before installation, with bronze guides being a consideration for extreme builds. While stock springs can work for mild builds under 350whp, upgrading to GSC springs is advised for builds over 400whp to control valve float at 9000+ RPM. This set is compatible with OEM retainers and GSC valve springs part #2003 or equivalents. The fitment includes the 2008-2015 Mitsubishi Lancer Evolution X (GSR, MR, and Final Edition submodels with the stock 4B11T cylinder head) and the 2009-2014 Mitsubishi Lancer Ralliart.