Supertech B58 Conical Dual Valve Spring Kit w/ Titanium Retainers (SPRK-B58B) – BMW M140i M240i 340i 440i M340i 540i Z4 M40i & Toyota GR Supra A90

Supertech Dual Conical Spring and Titanium Retainer Set for BMW and Toyota B58 engines

Part number: SPRK-B58B

Build your B58 the right way with Supertech’s dual conical spring and titanium retainer package. This uprated spring set is the go-to choice for tuned road cars and hard-use track builds that need dependable valve control at raised rev limits and higher boost. We run this kit on our own B58 projects at MJ Modifications and customer feedback has been superb for drivability, high rpm stability and long-term reliability.

Why this B58 spring and retainer kit is a smart upgrade

• Helps prevent valve float and bounce at increased rpm and boost pressure
• Dual conical architecture improves harmonic control for smoother valve motion
• Lightweight titanium retainers reduce mass for sharper valve response
• Manufactured from Superclean chrome silicon vanadium steel for durability
• Engineered to keep spring stress within safe limits for long service life
• Ideal alongside hybrid turbos, aggressive calibrations and frequent track days

What you get

• 24 dual conical valve springs
• 24 titanium retainers

Technical details

• Type: Conical valve spring
• Coil bind: 27.00 mm
• Maximum net lift: 12.20 mm
• Outer spring OD: 26.50 mm
• Outer spring ID: 18.70 mm
• Inner spring OD: 21.60 mm
• Inner spring ID: 13.80 mm
• Rate: 10.30 lbs per mm
• Open pressure: 180 lbs at 10 mm
• Seat pressure: 77 lbs at 40.10 mm

Vehicle fitment

For BMW and Toyota models using the B58 engine, including but not limited to:

• 1 Series F20 F21 M140i(x) B58 2016-2019
• 2 Series F22 F23 M240i(x) B58 2017-2020
• 3 Series F30 F31 F34 340i(x) B58 2016-2017
• 3 Series G20 G21 M340i(x) B58 2017+
• 4 Series F32 F33 F36 440i(x) B58 2016-2017
• 4 Series G22 G23 M440i(x) B58 2017+
• 5 Series G30 G31 540i(x) B58 2017-2020
• 6 Series G32 640i(x) B58 2017-2019
• 7 Series G11 G12 740i(x) B58 2016-2020
• 8 Series G14 G15 G16 840i(x) B58 2020
• X3 X3 M40i(x) B58 2017-2020
• X4 X4 M40i(x) B58 2018-2020
• X5 G05 X5 40i(x) B58 2018-2020
• X6 G06 X6 40i(x) B58 2019-2020
• X7 G07 X7 40i(x) B58 2019-2020
• Z4 G29 Z4 M40i B58 2017-2020
• Toyota GR Supra A90 B58 2020

Trusted by enthusiasts

Used on our in-house B58 builds and many customer cars, this Supertech spring and retainer set has proven itself under spirited road use, repeated heat cycles and sustained track sessions. If you are chasing consistent high rpm performance, this is a key reliability upgrade.

Fitting and support

Professional installation is strongly recommended for cylinder head and valve train work. For expert fitting, book with MJ Modifications in Warwickshire. Request a quote at info@mjmodifications.co.uk.

Images are for illustration purposes.

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