Forged connecting rods Mitsubishi 2.0 16v 4G63 6-bolt 21 mm pin (Eclipse / Talon) for forged pistons

The Mitsubishi 4G63 engine (6-bolt)

The 4G63 is a 1,997 cc inline-four (85 mm bore, 88 mm stroke) with double overhead camshafts and 16 valves, designed by Mitsubishi. In its turbocharged 4G63T form it powered the DSM platform (Eclipse 1G, Eagle Talon, Plymouth Laser) as well as the Galant VR-4, and became a benchmark for engine building. Blocks built up to around 1992 are identified by their six-bolt crankshaft fixing ("6-bolt"), reputed to be stiffer than the seven-bolt version that followed.

From the factory it produced about 195 hp, but its potential goes far beyond: with a larger turbo and suitable engine management, the 4G63T commonly handles 400 to 600 hp, and more in race configuration. This rise in output subjects the rotating assembly to loads that the cast-steel stock rods can no longer absorb.

Past roughly 350 to 400 hp, the connecting rod becomes the weak link: bending, stretch and then failure under inertial loads and combustion pressure. Switching to forged 4340-steel rods secures the bottom end and unlocks the true potential of the 6-bolt block.

Forged connecting rods

The connecting rod links the piston to the crankshaft and turns reciprocating motion into rotation. On a built engine it endures enormous forces on every cycle: it is the part that determines bottom-end reliability.

Forged from through-hardened steel, these rods offer fatigue strength and stiffness far above stock parts. They are built for competition — circuit racing, rally, drift, drag, hillclimb or time attack — and suit both a Stage 1 build and the most radical race engines.

Depending on the chosen profile and bolts, these 4G63 6-bolt rods support builds ranging from a few hundred horsepower to setups exceeding 600 hp, without ever becoming the breaking point of the rotating assembly.

Technical specifications of the 4G63 forged rods (6-bolt, 21 mm pin)

Tightening torque and stretch

Technical guide

Forged 4340 steel: what is it?

4340 steel is a chromium-nickel-molybdenum alloy steel, forged and then heat-treated. Forging aligns the metal grain and removes porosity, whereas a stock rod in cast or sintered steel has a far more fragile granular structure.

The result is a tensile strength on the order of 1,100 to 1,300 MPa, excellent fatigue resistance and a high tolerance to thermal and mechanical shock. It is the reference material for high-performance rods: it withstands high pressure cycles without deforming, where a stock sintered rod would give way.

Connecting rod profiles

The profile of the rod beam governs its behaviour under load. Two families are offered for this engine:

	H profile: an H-shaped beam, light and rigid, ideal for high rpm and moderate to strong turbo builds. It is the best weight / strength compromise for most engines.
	I-HD profile (I-Beam Heavy Duty, Manley Pro Series Turbo Tuff range): a reinforced, more substantial I-section designed to handle the very high boost pressures and elevated torque of the most aggressive 4G63 builds.

How to choose your rod bolts?

The bolts are the most highly stressed part of the rod: they hold the cap against inertial loads. All the rods on this page use 3/8" ARP bolts, available in two ranges.

	ARP 2000: the versatile reference. With a tensile strength of around 220,000 psi (≈ 1,517 MPa), it allows up to roughly 200 hp per cylinder in 3/8" diameter — covering the vast majority of 4G63 turbo builds — and holds engine speeds up to 8,500 rpm. Strong, reliable and with no particular storage constraints.
	ARP CA625+: the top-of-the-range bolt. Made from a superior alloy, it accepts higher clamping loads and torque than ARP 2000 and is aimed at the most extreme race engines, with very high boost pressure and sustained high rpm.

Measuring bolt stretch

Discover the ARP stretch gauge

The brands offered

Manley Performance: an American manufacturer recognised worldwide for its forged racing rods. The H-Beam and Pro Series I-Beam Turbo Tuff ranges equip the highest-performing DSM builds and are renowned for their manufacturing consistency and reliability under heavy load.

Glossary

Centre-to-centre: distance between the small-end and big-end bore axes. Small end: the upper end, which carries the piston pin. Big end: the lower end, which clamps the crankshaft journal. Stretch: the controlled elongation of the bolt that guarantees its clamping. Profile (H / I): the shape of the rod beam, key to stiffness and weight.

Vehicle compatibility for the Mitsubishi 4G63 engine (6-bolt)

OEM reference: (set of 4 connecting rods).

Why it is the most cost-effective solution?

A set of forged rods is a modest investment compared with the security it brings. On a built 4G63, a stock rod that lets go almost always destroys the block, the crankshaft and often the cylinder head.

Fitting forged rods from the start of the build avoids an engine failure whose bill far exceeds the price of the kit. On a built engine, it is the most cost-effective insurance part there is.