Forged connecting rods Nissan - 2.4L 16V - KA24 for forged pistons

The Nissan KA24 engine

The Nissan KA24 is a 2.4-litre naturally aspirated inline-four, produced from 1989 to 2004. With a displacement of 2,389 cc (89 mm bore x 96 mm stroke), it came as the SOHC KA24E and then the DOHC 16-valve KA24DE, which breathes better at high rpm. Its long-stroke design favours low and mid-range torque, and its sturdy bottom end earned it a reputation for outstanding durability.

The KA24DE mainly powered the Nissan 240SX (S13 and S14) and the North American Silvia, producing around 155 hp. Naturally aspirated as standard, it is one of the most popular tuning platforms in drift and motorsport: as soon as forged pistons, higher rpm or, above all, a turbocharger are added, the factory rod reaches its limits. It is then replaced by reinforced 4340 forged connecting rods that secure the bottom end.

Forged connecting rods

These rods are forged from high-strength 4340 steel and then machined to KA24 dimensions, with a 21 mm pin and a 164.97 mm centre-to-centre length. They make reliable a bottom end that quickly takes more than intended as soon as boost is added, the maximum rpm is raised, forged pistons are fitted or displacement is increased.

Intended for built engines, turbocharged as well as supercharged, they serve every discipline: rally, drift, drag racing, circuit and track use, hillclimb, time attack. They support Stage 2, Stage 3 and Stage 4+ builds up to a fully rebuilt competition engine, with two profiles to choose from, H or I-HD, from 615 to 630 g per rod.

Technical specifications of the KA24 forged connecting rods

Torque and bolt stretch

A successful assembly is decided before the wrench comes out: rod and bolt threads perfectly clean, free of old oil and machining residue, then ARP assembly lubricant laid down as an even film on the thread and under the nut. Without that preparation, friction varies from one bolt to the next and the torque read at the handle no longer tells you anything about the load actually passing through the bolt. That is the limit of the torque method, and it is why the values in the table above, those specified by the maker of the ARP 2000 bolts, must be applied without interpretation. On the eight bolts of the KA24, work up in increasing steps and alternate sides of the cap so the preload is installed without distorting the big end. Checking stretch with a gauge remains the reference: it reads the elongation of the bolt, and therefore the actual preload, regardless of friction. The instructions supplied with the Manley kit prevail in case of any discrepancy.

Technical guide

4340 forged steel: what is it?

Connecting rod profiles

	I-HD profile (Manley Pro Series I-Beam Turbo Tuff). A Heavy Duty version of the I-Beam, this rod keeps the same architecture but with a reinforced, thicker body, engineered to withstand much higher loads. It is intended for extreme loads, in high-power turbo, supercharged or nitrous oxide builds running high boost pressure.
	H-beam profile. With its two wide flat flanks joined by a central web, the “H” section gives the rod a massive, regular look along its entire length. It is the favoured profile for tuned naturally aspirated engines that rev high, such as the KA24, where it brings strong robustness to the bottom end.

How to choose your rod bolts?

On a KA24 the rod bolt is the part that decides what the bottom end will accept, in rpm as well as in cylinder pressure. The grade is therefore chosen by use: a drift engine spending its life at full load in the mid range does not load its bolts like a circuit engine holding maximum rpm, nor like a drag engine taking a few seconds of extreme load. Target power per cylinder then refines the choice. The bolts offered here are in 3/8"-38 mm.

ARP 2000, with a tensile strength of ~220,000 psi (~1,517 MPa), is the high-performance standard: up to 200 hp per cylinder in 3/8" and up to 8,500 rpm. On a built KA24 that covers most configurations, from the drift engine to the circuit engine. It is moreover the most common grade in circuit racing, track days, drift, rally, drag racing and hillclimb, and it calls for no particular storage constraint: the bolts wait for assembly with no special precaution.

Measuring bolt stretch

Buy the ARP stretch gauge →

The brands offered

MANLEY, an American forged connecting rod manufacturer since 1966. Machined from vacuum-degassed aerospace-grade 4340 steel, shot-peened and inspected one by one, its “Turbo Tuff” rods come in H-beam and I-beam profiles, with ARP 2000 bolts. A major name in engine building, from street to competition.

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 for the Nissan KA24 engine

These forged connecting rods are compatible with all vehicles fitted with the Nissan KA24 engine (2.4L 16V):

OEM reference: 12100-1KC0A (set of 4 rods).

Why it’s the most cost-effective solution?

On a KA24, a broken standard rod takes the piston with it and calls for a check of the block and crankshaft. Rebuilding the engine with standard parts means paying for rods and pistons only to recover exactly the same failure threshold. In other words, the same weakness is paid for twice.

For a comparable, often lower budget, a set of forged 4340 steel rods combined with forged pistons takes reliability and safety margin to another level, and leaves the door open to a later power increase. European engine builders have worked this way on Nissan four-cylinders for more than 15 years.

For the same budget: more reliability, more potential, more service life, for an engine that finally runs without holding back.