Mini Cooper / Peugeot / BMW / Citroën 1.6L R56 Turbo – ZRP Standard Black Nitride Intake Valves (Set of 8)

ZRP Standard Black Nitride Intake Valves are engineered for the 1.6L R56 turbocharged engine platform used in Mini Cooper, Peugeot, BMW, and Citroën models, including EP6 / Prince engine families. Designed for high-boost and high-RPM applications, these intake valves deliver excellent durability, dimensional stability, and reliable performance in both street and motorsport builds.

Manufactured from one-piece forged high-grade stainless steel (EV8 / 21-4N), each valve undergoes a specialized black nitriding process. This advanced surface hardening treatment diffuses nitrogen into the outer layer of the valve, significantly increasing wear resistance and fatigue strength while reducing friction between the valve stem and guide due to the smoother, hardened surface.

Unlike localized chrome coatings, the entire valve — including both stem and head — receives the black nitrided treatment. This ensures uniform surface protection, improved resistance to abrasion and valve seat recession, and extended service life in high-output turbocharged engines.

Each valve is precision forged, CNC-machined, polished, and tip hardened to meet strict dimensional tolerances. This guarantees accurate valve seating, stable high-RPM operation, and consistent sealing performance in both naturally aspirated and turbocharged configurations.

Technical Features

• Base Material: High-grade stainless steel (EV8 / 21-4N)

• Surface Hardness: Nitrided layer up to approx. 800 HV

• Manufacturing Process: Precision forged, CNC-machined, polished, and tip hardened

• Treatment Coverage: Full black nitriding of stem and valve head

• Dimensional Accuracy: Tight tolerances for concentricity, straightness, and sealing surface finish

Advantages

• Reduced stem-to-guide friction for lower wear

• Improved stability at high RPM and high boost

• Longer service life compared to untreated stainless-steel valves

• Reliable sealing in naturally aspirated and turbocharged engines

• Suitable for high-performance street and racing applications

Additional Information

• Set Quantity: 8 valves

• Material: Black Nitride

• Valve Size: 28.80 mm / 4.96 mm / 105.80 mm

• Application: 1.6L Citroën DS3 Turbo / Mini R56 Turbo / Peugeot 207RC

• Engine Family: EP6 (2010–2015) – Prince / N12 / N14 / N18B16