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Forged connecting rods BMW M42B18 M44B19 for forged pistons

New product

Set of 4 forged connecting rods in 4340 steel for BMW M42B18 and M44B19.

  • Brands: ZRP
  • Compatibility: 318is/318ti (E30, E36), Z3 1.9 (E36/7)
  • Engine codes: M42B18, M44B19
  • Bolts included: ARP 2000 or L19

More details

526,14 € tax incl.

-21%

666,00 € tax incl.

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  • The BMW M42 / M44 engine

    Launched in 1989, the M42 was BMW's first four-cylinder with double overhead camshafts and sixteen valves. With a 1,796 cc displacement (84 mm bore, 81 mm stroke), it pairs a sturdy cast-iron block with an aluminium cylinder head, chain-driven timing and hydraulic lifters. It powers the sporty 318is versions and comes as a saloon, coupé, convertible and compact.

    In 1995 the M44 took over, with displacement raised to 1,895 cc (85 mm bore, 83.5 mm stroke) for around 140 hp. It is found on the E36 3 Series 318is, 318ti and 318i convertible, as well as on the Z3 1.9 roadster. Smooth and eager at high revs, these engines make an excellent basis for tuning: as soon as you raise boost pressure, compression ratio or engine speed, switching to forged connecting rods secures the bottom end.

    Forged connecting rods

    Forged from high-strength 4340 steel, these reinforced connecting rods protect the bottom end as soon as power rises. They become essential when fitting forged pistons, raising engine speed, increasing boost pressure or gaining displacement.

    Designed to withstand the heavy loads of tuned engines, both forced-induction and high-revving naturally aspirated, they cover every discipline: rally, drift, drag racing, circuit, hillclimb and time attack, and support Stage 2 to Stage 4 builds and beyond.

    Technical specifications, BMW M42 / M44 forged connecting rods

    ReferenceBrandProfileBoltsPiston pin Ø
    OEM 22 mm
    Small-end widthBig-end Ø
    OEM 48 mm
    Big-end widthCenter-to-center
    OEM 140 mm
    Weight
    per rod
    R-BMW-007-IZRPIARP 2000-3/8"-38mm22 mm48 mm21.97 mm140 mm492 g
    R-BMW-007-I-L19ZRPIARP L19-3/8"-38mm22 mm48 mm21.97 mm140 mm492 g

    Tightening torque & bolt stretch

    RodBoltsTightening torqueRecommended stretch
    ZRP (R-BMW-007-I)ARP 200061 N·m0.140 – 0.152 mm
    ZRP (R-BMW-007-I-L19)ARP L1967.8 N·m0.152 – 0.165 mm

    Manufacturers recommend the bolt-stretch method (stretch gauge) as the reference: the instructions supplied with the kit always take precedence. The quoted torque values apply to assembly with ARP lubricant.

    Technical guide

    Forged 4340 steel, what is it?

    4340 is a nickel-chromium-molybdenum alloy steel used in aerospace and motorsport. Forged then heat-treated (quench and temper), it offers an excellent balance of tensile strength, fatigue life and ductility. Compared with sintered metal, it gains about 19% in yield strength, 8% in tensile strength and 19 to 37% in fatigue life, whereas the sintered part reaches its limits under high boost and risks failure.

    Connecting rod profiles

    Profil II profile. The I-beam section favours light weight: less material in the rod beam, hence less inertia and a real ability to rev high. It is the reference profile for high-revving naturally aspirated engines and modern turbo builds, where controlling moving mass is key.

    How to choose your rod bolts? ARP

    Rod bolts are among the most heavily loaded parts of the engine. The right choice means matching the steel grade to the real use of the build, then respecting the assembly torque and stretch.

    ARP 2000ARP 2000. A high-performance standard, it covers up to about 200 hp per cylinder in 3/8" and a maximum engine speed of around 8,500 rpm. Versatile and reliable, with no particular storage constraints, it suits circuit, trackday, drift, rally, drag racing and hillclimb.
    ARP L19ARP L19. Designed for engines pushed to the extreme (very high boost pressure, sustained high revs, high cylinder pressure), it accepts up to about 250 hp per cylinder in 3/8" and speeds near 10,000 rpm. It is the choice for big builds in drag racing, drift, rally and circuit. Sensitive to corrosion and hydrogen embrittlement, it must be stored and fitted oiled.

    Measuring bolt stretch

    Mesure de l'allongement

    The most accurate way to tighten a rod bolt is to measure its stretch with a dial indicator (stretch gauge) rather than relying on torque alone. Aim for the manufacturer's recommended stretch, bolt oiled, to ensure correct preload without overstressing.

    Buy the ARP stretch gauge →

    The brand offered

    ZRPZRP. A Greek brand of high-performance forged connecting rods, made by Drakos Engineering in Athens. Each rod is forged from 4340 steel, precision-machined and balanced to ±1 g to stay reliable at high revs. Offered here in I profile with ARP 2000 or ARP L19 bolts, they are designed and inspected in Greece for rally, circuit and drift.

    Glossary

    Schéma bielle1) Small end
    2) Small-end diameter
    3) Rod beam
    4) Rod bolt
    5) Big end
    6) Nut / rod bolt
    7) Rod cap
    8) Big-end diameter
    9) Center-to-center

    Vehicle compatibility

    BrandModel (chassis)Engine codePowerYears
    BMW3 Series 318is (E30)M42B18136 hp1989–1991
    BMW3 Series 318i Convertible (E30)M42B18140 hp1990–1992
    BMW3 Series 318i (E36)M42B18140 hp1992–1995
    BMW3 Series 318is saloon / coupé (E36)M42B18140 hp1992–1995
    BMW3 Series 318i Convertible (E36)M42B18140 hp1994–1995
    BMW3 Series Compact 318ti (E36)M42B18140 hp1994–1995
    BMW3 Series 318is saloon / coupé (E36)M44B19140 hp1995–1999
    BMW3 Series 318is Convertible (E36)M44B19140 hp1996–1999
    BMW3 Series Compact 318ti (E36)M44B19140 hp1996–1999
    BMWZ3 Roadster 1.9 (E36/7)M44B19140 hp1995–1999

    OEM reference: 11 24 1 437 617 (rod set).

    Why it is the most cost-effective solution

    On a tuned M42 or M44, a connecting-rod failure almost always destroys the block and cylinder head. A set of forged rods costs a fraction of a new engine and a long downtime. It is the guarantee of a reliable bottom end, able to handle the target power for the long run, mile after mile.