Forged connecting rods Nissan - 2.5L & 2.6L 24V Turbo - RB25DET / RB26DETT (Skyline GT-R) 21 mm pin for forged pistons

The Nissan RB25DET / RB26DETT engine

The RB26DETT is the 2.6 L twin-turbo inline-six, 24-valve engine that made the legend of the Nissan Skyline GT-R (R32, R33 and R34) and of the Stagea 260RS wagon. Its smaller brother, the 2.5 L single-turbo RB25DET, powers the Skyline GTS-25t and GT-t, the Laurel, Stagea, Cedric and Gloria. With its famously indestructible closed-deck block, twin-cam head and seven-bearing crankshaft, the RB platform copes with power levels far beyond stock, provided its weak links are reinforced. On these tuned engines the factory rods become the breaking point as soon as boost pressure and engine speed rise.

The forged connecting rods

Machined from drop-forged 4340 chrome-molybdenum steel, these rods deliver fatigue strength and bending resistance far beyond the original sintered rods. They are designed for engine building in motorsport as well as on the open road: circuit, time attack, drift, drag, rally and hillclimb. Depending on the chosen profile and bolts, the kit supports builds from Stage 1 to Stage 3 and beyond, with power outputs commonly ranging from 400 to over 800 hp on a built RB. The complete set of 6 rods is weight-matched to preserve the balance of the rotating assembly and reliability at high rpm.

Technical specifications

OEM reference: 12100-05U01 (RB26DETT); 12100-AB025 (R34 V-Spec) (set of 6 rods).

Tightening torque and stretch

Forged rod bolts are set by measuring bolt stretch with a gauge, not by torque alone. The values below are indicative: always refer to the bolt manufacturer's instructions.

Technical guide

4340 forged steel

4340 is a nickel-chromium-molybdenum alloy recognised as the benchmark for high-performance connecting rods. Forged then heat-treated, it keeps a continuous grain flow giving tensile strength of around 1,000 to 1,200 MPa and toughness far greater than a mass-produced sintered rod, which is brittle by nature. Where the original rod is optimised for cost and factory efficiency, the forged 4340 rod is sized to absorb overpressure, sudden rpm surges and the thousands of cycles of intensive use.

Rod profiles

	I profile (I-HD) : reinforced I-beam, the best weight / stiffness compromise for most turbo builds. Wössner's A-Beam is an optimised I-beam.
	I-3P profile : Boostline's three-piece I-beam, designed for very high power while staying light and precise.
	H profile : H-beam, valued for its robustness and its resistance to high torque, notably on shorter stroker versions.

This listing offers several profiles depending on the brand: I-HD (ZRP, Manley), optimised A-Beam I (Wössner), three-piece I-3P (Boostline) and H (ZRP, Manley). The choice depends on the target power and use, the specification table giving the center-to-center length and weight of each reference.

How to choose your rod bolts?

	ARP 2000 is the reference bolt in 3/8" diameter. With a tensile strength of about 220,000 psi (1,517 MPa), it secures power of around 200 hp per cylinder and rpm up to 8,500. Versatile and with no storage constraints, it covers circuit, drift, rally, drag and hillclimb.
	ARP L19 in 3/8" uses a higher-strength alloy (about 260,000 psi). It targets serious turbo builds, up to nearly 250 hp per cylinder. More sensitive to oxidation, it must be fitted and stored oiled.
	ARP CA625+ in 3/8" is ARP's top Custom Age maraging steel (about 260,000 to 280,000 psi), with extreme fatigue resistance. It is the bolt for the most violent builds, drag and records, for the highest power levels.

Stretch measurement

Discover the ARP stretch gauge

Available brands

	Boostline is the connecting-rod line of the American Wiseco group, whose history goes back to 1941. Its patented three-pocket shape borrows the stiffness of an I-beam and the strength of an H-beam: that is the I-3P chosen for the RB. Forged in 4340 steel and machined in the United States, it ships with ARP 2000 bolts, with an ARP Custom Age 625+ version for the hardest-worked engines.
	Manley has been building forged rods in the United States since 1966. Its “Turbo Tuff” bodies are cut from vacuum-degassed aerospace-grade 4340 steel, shot-peened to delay crack initiation and inspected piece by piece. For the RB the choice is between the H profile and the I-HD profile, with ARP 2000 or ARP Custom Age 625+ bolts depending on the part number.
	Wössner brings German machining discipline to the RB: a forged-steel rod in an I profile, held to tight dimensions, weighed then matched set by set before shipping, with ARP 2000 hardware. It is the choice for a carefully executed build, where consistent masses and traceable European production matter as much as raw strength.
	ZRP is the catalogue’s Greek marque, born in Athens under Alex Drakos. Its RB rods start from forged 4340 steel and are then fully machined, with the set of six weight-matched to within ±1 g. Two architectures appear here: the I-HD profile and the H profile, each available with ARP 2000 or ARP L19 bolts. Development and final inspection take place in Greece, in a culture shaped by rallying, circuit racing and drift.

Four forged competition rod makers are gathered on this reference: ZRP (Alex Drakos rods, Athens), Wössner, Boostline and Manley. Each offers several profiles and bolt grades, from a reliable entry-level kit to I-3P and Custom Age 625+ assemblies for extreme builds.

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

Vehicle compatibility

Rods compatible with the following Nissan RB25DET and RB26DETT engines (21 mm piston pin):

Why it is the most economical solution

Investing in a set of forged rods costs far less than an engine failure: on a built RB, an original rod that lets go destroys the block, crankshaft and head. By choosing weight-matched forged rods from the start, you make your build reliable for the long term and avoid a full rebuild, for a marginal extra cost compared with the price of a new engine.