Forged connecting rods Honda F24 2.4 16V stroker (S2000) for forged pistons

The Honda F24 engine (F20C-based stroker)

"F24" is not a factory Honda engine but the tuner's name for an F20C stroked to about 2.4 L. The original F20C is the 2.0 L 16-valve DOHC VTEC four-cylinder of the Honda S2000 (AP1), famous for its 240 to 250 hp naturally aspirated and one of the highest redlines ever fitted to a production engine, around 9,000 rpm. Converting it to F24 means fitting a longer-stroke crankshaft for more displacement: the forged rods offered here, with a shortened 145.5 mm center-to-center length and a 23 mm piston pin, keep the deck height correct despite that added stroke. The result is a build with markedly higher torque, whether it stays high-compression naturally aspirated or gains a turbocharger. At those stress levels the factory rods become the weak link: replacing them with forged rods is the first safeguard of a reliable, lasting stroker.

The forged connecting rods

Drop-forged and precision-machined, these rods withstand bending, compression and fatigue loads far beyond those the factory sintered rods tolerate. They suit every sporting use of a prepared F-series engine: circuit, time attack, drift, drag, rally and hillclimb. Depending on the build, they support a Stage 2 as readily as a Stage 3 or a Stage 4 pushed in compression, rpm and, where fitted, boost. Supplied as a complete set of 4, weight-matched, they preserve the balance of the rotating assembly and the high-rpm resistance typical of the F block. All adopt the 145.5 mm center-to-center length and the 23 mm piston pin specific to the F24 stroker.

Technical specifications of the F24 forged rods (23 mm pin)

Tightening torque and stretch

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

Forged rods technical guide

4340 forged steel

These rods are forged from 4340 low-alloy nickel-chromium-molybdenum steel, the benchmark for high-performance rods. Forged, then quenched and tempered, it keeps a continuous grain flow that gives high tensile strength and excellent fatigue life, two decisive qualities on a torque-increased stroker. Compared with a cost-optimised sintered factory rod, a forged 4340 rod gains about +19% yield strength, +8% tensile strength and +19 to +37% in fatigue endurance. It is this margin that lets a stroked F20C absorb over-revs and torque increases without breakage.

The rod profile

The range is offered in the reinforced I-HD profile, an I-beam by ZRP. It is the best all-round choice for an F24: stiff, lightened and proven on heavily stressed engines. The specification table gives the center-to-center length, big-end diameter, big-end width and weight of each reference.

I-HD profile: reinforced Heavy Duty I-beam from the ZRP Pro Series range, designed for the best weight / stiffness compromise on demanding builds; its optimised section resists buckling under the heavy loads of a turbo or high-compression naturally aspirated stroker.

How to choose your rod bolts?

	ARP 2000: the versatile 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 builds, up to about 200 hp per cylinder, at speeds reaching 8,500 rpm. It is the default choice for a reliability-focused F24 stroker.
	ARP L19: a higher-grade alloy (≈ 260,000 psi / 1,793 MPa) for the most heavily stressed engines in torque and rpm, up to about 250 hp per cylinder in 3/8". More sensitive to corrosion and hydrogen embrittlement, it must be oiled and stored with care.

Measuring bolt stretch

Discover the ARP stretch gauge

The brand offered

This F24 range is made by ZRP, a maker of precision-machined forged competition rods, weight-matched to ± 1 g. The Pro Series I-HD line is recognised for its robustness on heavily prepared engines. Each reference is supplied as a complete set of 4, with its dedicated ARP bolts.

ZRP

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

Compatibility: Honda F20C engine base (S2000)

These rods equip "F24" builds, a Honda F20C stroked to about 2.4 L. The donor base is the F20C of the Honda S2000 (AP1):

Why it is the most economical solution

A set of forged rods costs far less than an engine failure: on a stroked F24 pushed in torque and rpm, an original rod that lets go takes out the block, the crankshaft and very often the cylinder head. By fitting weight-matched forged rods from the start, you make your build reliable for the long term and avoid a full rebuild, for a negligible extra cost compared with the price of a new engine.