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Reduced price! Coussinets de bielles trimétal ACL BMW MINI B48A20 B48B20 View larger

Trimetal connecting rod bearings ACL BMW MINI B48A20 B48B20

New product

Set of 8 trimetal connecting rod half-bearings for BMW and MINI 2.0 turbo B48.

  • Brand and treatment: ACL Race
  • Compatibility: BMW 1 to 7 Series, X1 to X4, Z4; MINI Cooper S, John Cooper Works
  • Engine codes: B48A20, B48B20
  • Available sizes: standard to +0.25 mm, increased-clearance version (HX)

More details

137,85 € tax incl.

-5%

145,10 € tax incl.

IN STOCK

Stock NSB France : 1 Item

  • The BMW B48 four-cylinder engine

    Fitted to the MINI Cooper S and John Cooper Works and to a wide range of BMW models, from the 1 to 7 Series to the X1, X2, X3, X4 and Z4, the B48 is a turbocharged 1,998 cc inline four with an 82 mm bore and a 94.6 mm stroke, twin overhead camshafts and 16 valves. It comes in two versions, B48A20 and B48B20, which share the same crankpin diameter: a single bearing set covers the whole family.

    From the factory, BMW fits this engine with standard production connecting rod bearings (part numbers 11 24 7 620 969 and 11 24 7 620 970). These bearings are sized for the loads of the original engine: as soon as power, engine speed or boost pressure increase, they reach their limits.

    Trimetal connecting rod bearings

    A trimetal bearing stacks three layers: a steel back, a copper-lead intermediate layer with high load capacity and an anti-friction running surface that protects the journal. The complete set contains 8 half shells, four pairs for a four-cylinder engine.

    The original bearing relies on an aluminium alloy over a steel back, intended for low to medium loads, whereas trimetal is designed for high, sustained loads: an aluminium bi-metal takes around 8,000 psi, a performance trimetal up to 12,000 psi, 50% more. Hence better resistance and better durability on turbocharged, supercharged and high-revving engines.

    Technical specifications

    Fitment dimensions common to all references
    ACL bearings
    Crankpin Ø 49.975 / 49.992 mm
    Housing bore Ø 53.600 / 53.619 mm
    Width 19.55 mm    		OEM reference
    Part no. 11 24 7 620 969
    and 11 24 7 620 970
    ReferenceBrand and treatmentSizeWall thickness (mm)
    4B1510H-STDACL Race - UntreatedStandard1.793
    4B1510HX-STDACL Race - UntreatedStd, increased clearance (HX)1.780
    4B1510H-.025ACL Race - Untreated+0.0251.806
    4B1510H-.25ACL Race - Untreated+0.251.918

    Running clearance

    The running clearance is the gap between the bearing and the journal where the oil film flows.

    In operation, the crankshaft journal does not rub against the bearing: it rides on this oil film, which carries the load. Clearance sets the thickness of this film: too tight, oil flows poorly, temperature rises and the risk of seizure increases; too loose, oil escapes, the film loses load-carrying capacity and oil pressure drops. The right clearance is the balance between adequate lubrication and a well-maintained oil film.

    Size / gradeWhen to choose itACL Race Series
    Standard (STD)Standard journal, not reground0.053 to 0.063 mm
    Increased clearance (HX)Wider clearance: high oil flow, high rpm0.078 to 0.088 mm
    +0.025 mmPolished journal0.053 to 0.063 mm
    +0.25 mmJournal reground to 0.25 mm0.053 to 0.063 mm

    Checking on assembly: lay a calibrated strip (Plastigauge) on the journal, torque the rod cap to spec, then compare the crushed strip against the gauge to read the clearance.

    Plastigauge

    Order the Plastigauge →

    Technical guide

    The ACL rod bearings shown here are trimetal bearings, designed for engine building and racing. Compared with an original bearing, they handle far higher loads: they cope with increased power, high rpm or the addition of a turbo or supercharger, where a standard bearing quickly reaches its limit.

    The brand

    ACLACL Bearing Company, an Australian manufacturer of high-performance engine bearings since 1949, offers with its Race Series precise trimetal bearings, available in many sizes and proven on built engines worldwide.

    Vehicle compatibility

    This connecting rod bearing set fits the B48 four-cylinder (B48A20 and B48B20) of the following BMW and MINI models:

    BrandModel (chassis)Engine codePowerYears
    BMW1 Series (F20) 120 i / 125 iB48B20184–224 hp2016–2019
    BMW1 Series (F21) 120 i / 125 iB48B20184–224 hp2015–2019
    BMW1 Series (F52) 120 iB48A20192 hpsince 2018
    BMW1 Series (F40) M 135 i xDriveB48A20306 hpsince 2019
    BMW2 Series Active Tourer (F45) 220 i / 220 i Flex / 225 i / 225 i xDriveB48A20163–231 hp2013–2021
    BMW2 Series Coupé (F22, F87) 220 i / 225 i / 230 iB48B20184–252 hp2015–2021
    BMW2 Series Convertible (F23) 220 i / 225 i / 230 i / 230 i xDriveB48B20184–252 hp2015–2021
    BMW2 Series Gran Tourer (F46) 220 iB48A20163–192 hpsince 2015
    BMW3 Series (F30, F80) 320 i / 320 i xDrive / 330 e / 330 i / 330 i xDriveB48B20184–252 hp2015–2018
    BMW3 Series (G20, G80, G28) 320 i / 320 i xDrive / 330 i / 330 i xDriveB48B20184–258 hpsince 2018
    BMW3 Series Gran Turismo (F34) 320 i / 320 i xDrive / 330 i / 330 i xDriveB48B20163–252 hpsince 2016
    BMW3 Series Touring (F31) 320 i / 320 i xDrive / 330 i / 330 i xDriveB48B20184–252 hp2015–2019
    BMW4 Series Coupé (F32, F82) 420 i / 420 i xDrive / 425 i / 430 i / 430 i xDriveB48B20163–252 hp2016–2020
    BMW4 Series Convertible (F33, F83) 420 i / 425 i / 430 i / 430 i xDriveB48B20163–252 hp2016–2020
    BMW4 Series Gran Coupe (F36) 420 i / 420 i xDrive / 425 i / 430 i / 430 i xDriveB48B20163–252 hp2016–2021
    BMW5 Series (G30, F90) 520 i / 530 e Plug-in Hybrid / 530 e Plug-in-Hybrid xDrive / 530 i / 530 i xDriveB48B20163–252 hpsince 2016
    BMW5 Series Touring (G31) 520 i / 530 i / 530 i xDriveB48B20163–252 hp2017–2020
    BMW6 Series Gran Turismo (G32) 630 iB48B20258 hp2017–2020
    BMW7 Series (G11, G12) 730 i, Li / 740 Le xDrive / 740 e, LeB48B20258–326 hp2015–2022
    BMWX1 (F48) sDrive 20 i / xDrive 20 i / xDrive 25 iB48A20192–231 hp2015–2022
    BMWX2 (F39) M35 i / sDrive 20 i / xDrive 20 iB48A20192–306 hp2017–2023
    BMWX3 (G01, F97, G08) sDrive 20 i / xDrive 20 i / xDrive 30 e Plug-in-Hybrid / xDrive 30 iB48B20184–292 hpsince 2017
    BMWX4 (G02, F98) xDrive 20 i / xDrive 30 iB48B20184–252 hpsince 2018
    BMWZ4 Roadster (G29) sDrive 20 i / sDrive 30 iB48B20163–258 hpsince 2018
    MINIMINI (F55) Cooper S / Cooper S JCWB48A20163–211 hpsince 2013
    MINIMINI (F56) Cooper S / Cooper S JCW / John Cooper WorksB48A20163–231 hpsince 2013
    MINIMINI Clubman (F54) Cooper S / Cooper S ALL4 / Cooper S JCW / Cooper S JCW ALL4 / John Cooper WorksB48A20163–306 hpsince 2014
    MINIMINI Countryman (F60) Cooper S / Cooper S ALL4 / John Cooper Works ALL4B48A20163–306 hpsince 2016
    MINIMINI Convertible (F57) Cooper S / Cooper S JCW / John Cooper WorksB48A20163–231 hpsince 2014

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