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Forged connecting rods Honda K20 2.0 16V i-VTEC 148.5 mm center-to-center (stroker build) for forged pistons

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Set of 4 forged 4340 ZRP rods, long 148.5 mm center-to-center, for stroker builds of the Honda K20 2.0 16V i-VTEC (22 mm pin).

  • ZRP brand; H profile
  • Alternative 148.5 mm length (K20A2, K20Z1, K20A3)
  • Not drop-in: adapted pistons required
  • ARP 2000 or L19 bolts (3/8")

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476,86 € tax incl.

-26%

644,40 € tax incl.

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  • The Honda K20 engine (2.0 16V i-VTEC)

    A 2.0 L (1998 cc) four-cylinder from the K family, the K20 combines sixteen valves, twin cams and i-VTEC variable timing acting on both valve lift and phasing. In its most accomplished naturally aspirated forms (K20A2, K20Z1, K20A3) it spins to around 8,400 rpm and makes 160 to 220 hp, which made it the engine of the Civic Type R EP3 and Acura RSX Type-S. As soon as its stroke, compression height or ratio is altered, typically in a stroker build, the rotating-assembly geometry changes and the factory sintered rod no longer fits. It then becomes the weak point of the assembly, unable to cope durably with the new cylinder pressures and inertia loads. Fitting forged rods of the chosen length, weight-matched, is the foundation of a lastingly reliable stroker K20.

    The forged connecting rods (148.5 mm length)

    These ZRP rods stand out through their long 148.5 mm center-to-center length, above the K20's factory dimension: they are designed for modified-geometry builds (stroker, revised compression height) and not for a like-for-like swap. Drop-forged then precision-machined, they tolerate compression, bending and fatigue loads far beyond the factory sintered rods. They suit every demanding use: circuit, time attack, drift, drag, rally and hillclimb, on a hard naturally aspirated K20 as on a Stage 2, Stage 3 or Stage 4 turbo or supercharger conversion. Supplied as a complete weight-matched set of 4, they keep the K20's 22 mm piston pin while requiring, because of their length, pistons with adapted compression height.

    H profile:H profile: H-beam by ZRP; its two flat flanks give excellent bending stiffness for a controlled weight, a versatile, proven choice for most naturally aspirated or lightly boosted stroker K20 builds.

    The 148.5 mm range offers a single ZRP profile: the versatile, proven H, forged in 4340 steel. The specification table details, for each reference, the center-to-center length, big-end diameter and width and the weight, to choose by the power and rpm target of the stroker build.

    Technical specifications of the K20 rods (22 mm pin, 148.5 mm center-to-center)

    ReferenceBrandProfileBoltsPin Ø (mm)Small-end width (mm)Big-end Ø (mm)Big-end width (mm)Center-to-center (mm)Weight (g)
    R-HON-013HLZRPHARP 2000-3/8"-38mm225119,83148,5453
    R-HON-013HL-L19ZRPHARP L19-3/8"-38mm225119,83148,5453

    Forged rods technical guide

    4340 forged steel

    The beam is forged from 4340 low-alloy nickel-chromium-molybdenum steel, the benchmark alloy for race rods. Forged, quenched then tempered, it keeps a continuous grain flow that gives high tensile strength and outstanding fatigue life, two decisive assets on a stroker K20 stressed high and long. Compared with a factory sintered rod, designed above all for series production cost, a forged 4340 rod offers about +19% yield strength, +8% tensile strength and +19 to +37% fatigue endurance. This mechanical reserve absorbs, without breaking, the pressure peaks and inertia loads of a K20 whose stroke has been lengthened.

    The rod profile

    The 148.5 mm range offers a single ZRP profile: the versatile, proven H, forged in 4340 steel. The specification table details, for each reference, the center-to-center length, big-end diameter and width and the weight, to choose by the power and rpm target of the stroker build.

    How to choose your rod bolts? ARP

    ARPARP 2000: the all-round benchmark alloy, with a tensile strength of about 220,000 psi (1,517 MPa). Offered here in 3/8" diameter, it covers the vast majority of stroker K20 builds, up to about 200 hp per cylinder, at speeds reaching 9,000 rpm. It is the default choice for an engine made reliable for sustained sporting use.
    ARPARP L19: a very-high-strength steel (approx. 260,000 psi / 1,793 MPa), stiffer, reserved for the most heavily stressed stroker K20s, up to about 250 hp per cylinder and the highest engine speeds. In 3/8" diameter it markedly raises the safety margin (note: corrosion-sensitive, it requires careful storage).

    Measuring bolt stretch

    Measuring bolt stretch

    On a forged rod, correct bolt preload is checked by its stretch, read with a dial gauge, and not by torque alone: lubrication and run-in distort the torque reading. Always refer to the bolt maker's stretch values, recalled in the table above.

    Discover the ARP stretch gauge

    The brand offered

    ZRP
    ZRP

    This 148.5 mm range is made by ZRP, a race forged-rod maker. The H profile is forged from 4340 steel and supplied as a complete set of 4, with its dedicated ARP bolts.

    Vehicle compatibility

    Alternative-length rods (148.5 mm): these are not drop-in replacement rods. Longer than the K20's factory dimension, they are intended for specific-geometry setups and stroker builds on the K20A2, K20Z1 and K20A3 engines below, and require pistons with adapted compression height:

    BrandModel (chassis)Engine codePowerYears
    HondaCivic Type R (EP3)K20A2147 kW (200 ch)2001–2005
    AcuraRSX Type-S (DC5)K20A2 / K20Z1147–154 kW (200–210 ch)2002–2006
    HondaCivic 2.0 Sport (EP3)K20A3118 kW (160 ch)2001–2005

    Tightening torque and stretch

    On these rods, tightening is controlled by bolt stretch, measured with a gauge, rather than by torque alone. The values below are a guide: always follow the bolt maker's instructions.

    RodBoltsTightening torqueRecommended stretch (mm)
    ZRP H (R-HON-013HL)ARP 200061 N·m0,140 – 0,152
    ZRP H (R-HON-013HL-L19)ARP L1967,8 N·m0,152 – 0,165

    Glossary

    1) Small end
    2) Small-end diameter
    3) Rod beam
    4) Rod bolt
    5) Big end
    6) Rod nut / bolt
    7) Rod cap
    8) Big-end diameter
    9) Center-to-center

    Why is it the most economical solution?

    A set of forged rods costs vastly less than a blown engine: on a stroker K20 pushed in rpm or load, an unsuitable rod that lets go takes out the block, the crankshaft and often the head. By choosing the right forged-rod length, weight-matched, from the outset, you make your build reliable for the long term and spare yourself a full rebuild, for a negligible extra cost next to a new engine.