Supertech Performance NIVN-1052 Black Nitrided Intake Valve Nissan Oversize - RB25 1mm

The Supertech Performance NIVN-1052 is a high-performance intake valve engineered for the Nissan RB25 24V DOHC engine. Featuring a 35.15mm (+1mm oversize) head diameter and a stem diameter of 5.97mm, this valve is constructed from one-piece forged Stainless Steel 21-4N (EV8) — a premium alloy chosen for its exceptional strength, heat resistance, and long-term durability under racing conditions.

Black Nitride Surface Treatment:

The NIVN-1052 receives Supertech's industry-leading Black Nitride hardening treatment, applied to the entire valve surface. This process produces a surface microhardness of 800HV minimum — significantly harder than the base stainless steel — while retaining ductility beneath the treated layer. The result is a valve that resists wear, reduces friction between the stem and guide, and performs reliably with aggressive fuel blends including alcohols, nitro, and other high-energy mixtures.

Key Features:

• Material: One-piece forged Stainless Steel 21-4N (EV8 alloy)
• Head Diameter: 35.15mm (+1.0mm oversize)
• Stem Diameter: 5.97mm
• Groove Type: Single groove
• Surface Finish: Black Nitride — applied to the entire valve (not just the stem)
• Undercut & Back-Cut: Yes — improves airflow and reduces valve head weight
• Minimum Surface Hardness: 800HV
• Compatible Valve Seats: Nodular iron, steel powder metal, hard aluminum-copper, and beryllium copper seats
• Sold individually — order the quantity equal to the number of intake valves your engine requires

The nitrided layer bonds at a microscopic level and will not flake or fracture under impact, making it an ideal choice for high-RPM and forced-induction builds. Supertech valves are engineered to reduce valve-to-guide friction losses — a critical advantage in high-revving applications where internal friction directly impacts power output.