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BMW M52 Stainless Steel Black Nitride Exhaust Valves

 
Stainless Steel Black Nitride Exhaust Valves
Engine
BMW
    M52
    • B38B15
    • B48
    • B58B30
    • M20
    • M20 B25
    • M42
    • M50
    • M52
    • M54
    • M70
    • N53
    • N54 Turbo
    • N55 Turbo
    • S14
    • S38
    • S42
    • S50
    • S50B30 Euro Version
    • S50B32 Euro Version
    • S52
    • S54B32
    • S55 Turbo
    • S63B44
    • S65 V8
    • S85 V10
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    Choose your specs

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    Valve Size

    - Select -
    • Standard
    • Oversize +1mm

    Groove Type

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    • Single Groove
    • Triple Groove

    Valve Set

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    • Each
    • Set of 12
    Supertech valve details – stem, head and tip close-ups

    Stainless Steel Black Nitride Exhaust Valves

    Supertech Stainless Steel Black Nitride (BN) Exhaust Valves combine the strength of EV8/21-4N stainless with a low-friction, wear-resistant surface. The result is reliable sealing, smoother operation, and long service life for street performance, track days, and moderate boost applications.

    • EV8 stainless base with BN surface for durability
    • Hardened tips, controlled stems, and swirl-polished heads
    • OE and oversize options (by application)

    Key Benefits

    Why Choose Stainless + BN

    • EV8 stainless base material for hot hardness and durability.
    • Black Nitride surface helps reduce friction and scuffing.
    • Improved wear and corrosion resistance for daily use and track days.
    • Controlled stem finish and hardened tips to extend guide and follower life.
    • Offered in OE diameter and oversize options where supported.

    Materials and Surface Finish

    Stainless EV8 (21-4N)

    High strength at temperature with consistent seat-face accuracy and stem concentricity.

    • Excellent fatigue resistance for long service life.
    • Stable performance in street and track-day duty.

    Black Nitride (BN) Finish

    A hard, low-friction surface treatment that promotes smoother motion and wear resistance.

    • Helps reduce guide and seat wear.
    • Dark appearance for quick identification.

    Surface Details

    • Swirl-polished heads for smoother boundary layer.
    • Controlled stem finish for consistent clearances.
    • Hardened tips for follower and lash component life.

    Engineering Options

    Geometry

    • Flat, dished, and tulip head shapes by application.
    • Undercut or straight stems as validated.

    Sizes

    • OE diameter for stock ports and chambers.
    • Oversize options for ported heads where supported.

    Compatibility

    • Match with Supertech springs and retainers for your cam profile.
    • Works with performance guides and seat materials.

    Use Cases

    Street and NA

    Stainless + BN offers excellent durability and smooth operation for daily-driven and naturally aspirated builds.

    Moderate Boost

    Suitable for moderate turbo and supercharged applications. For sustained high EGT or endurance racing, consider Inconel exhaust valves.

    Installation Notes

    • Measure guide ID and set stem-to-guide clearance by material.
    • Cut seats to proper angles and contact width; verify concentricity.
    • Check installed height, seat pressure, coil bind, and retainer-to-seal clearance.
    • Verify piston-to-valve clearance at intended lift and timing.
    • Follow appropriate break-in and inspection intervals for your application.

    FAQ

    How does Black Nitride compare to Inconel?

    BN is a surface treatment that improves wear and reduces friction on stainless valves. Inconel is a high-temperature alloy. For the highest EGT and endurance racing, Inconel is recommended.

    Does BN change valve dimensions?

    BN is a thin surface layer. Always verify stem-to-guide clearance during assembly to ensure proper fit.

    Can I re-coat or refinish BN valves?

    Consult your machine shop and Supertech support for guidance. Do not remove material that affects stem finish or seat geometry.

    Do I need upgraded springs?

    Use springs matched to your cam profile and valve mass. Proper seat and open pressures control valve motion at RPM.