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Supertech SPRK-MCB58 – Beehive Valve Spring Kit (BMW B58)
Key Features


Complete kit of 24 beehive springs purpose-built for the 3.0 L BMW B58 engine found in the latest 340i, 440i, M240i, Z4 M40i and Toyota GR Supra.


Seat pressure 75 lbs @ 37 mm and open pressure 155 lbs @ 10 mm lift—ample margin for aggressive cam profiles and high boost.


Maximum lift 12.2 mm with a coil-bind height of 23.20 mm, ensuring compatibility with popular performance camshafts.


Tapered beehive shape lowers moving mass and raises the natural frequency of the spring, suppressing valve-train resonance beyond 7 000 RPM.


Includes your choice of steel (TE) or titanium (TI) retainers plus hardened steel spring seats for precise location and reduced rotating weight.


Crafted from premium chrome-silicon alloy—heat-treated and shot-peened for exceptional fatigue life under sustained track conditions.


Direct drop-in with OEM guides and Supertech or factory valves; no cylinder-head machining required.


Technical Specifications





Parameter
Value




Springs in kit
24


Seat pressure
75 lbs @ 37 mm install height


Open pressure
155 lbs @ 10 mm lift


Spring rate
≈ 8 lbs/mm


Maximum lift
12.2 mm


Coil-bind height
23.20 mm


OD (bottom / top)
24.4 mm / 21.0 mm


ID (bottom / top)
17.6 mm / 14.2 mm


Included hardware
24 springs, 24 retainers (TE or TI), 24 seat locators








Applications


BMW B58 engines: F- & G-series 340i, 440i, M240i, Z4 M40i


Toyota GR Supra 3.0 (A90/A91)


Builds targeting >7 500 RPM, high-boost forced induction, or extended track-day abuse.


Benefits


Eliminates valve float—maintains full cam control at elevated RPM and boost levels.


Improves throttle response—lighter retainers reduce reciprocating mass.


Future-proof—headroom for even more aggressive cams or additional boost down the road.


Track-ready durability—alloy selection and heat treatment resist thermal fatigue during long sessions.