Manley 15024-4 H-Tuff Connecting Rods ARP Subaru EJ20 EJ25 WRX STI 5.137in 4340

Vehicle Fitment

• 2002-2014 Subaru Impreza WRX (EJ205, 2.0L DOHC Turbo)
• 2004-2021 Subaru WRX STI (EJ257, 2.5L DOHC Turbo)
• 2004-2013 Subaru Forester XT (EJ255, 2.5L DOHC Turbo) - see EJ255 piston note in Fitment Notes
• 2005-2009 Subaru Outback XT (EJ255, 2.5L DOHC Turbo) - see EJ255 piston note in Fitment Notes
• 2005-2012 Subaru Legacy GT (EJ255, 2.5L DOHC Turbo) - see EJ255 piston note in Fitment Notes
• 2007-2009 Subaru Legacy GT Spec B (EJ255, 2.5L DOHC Turbo) - see EJ255 piston note in Fitment Notes

Fitment Notes

• WARNING: EJ255 ENGINES (Forester XT, Outback XT, Legacy GT / Spec B): These rods are compatible with EJ255 engines ONLY when paired with aftermarket pistons that do NOT require a tapered connecting rod small end. OEM EJ255 pistons use a tapered wrist pin bore that is incompatible with the straight small end bore of these H-Tuff rods - using OEM EJ255 pistons will result in improper fitment and risk of engine damage
• Fits EJ205 and EJ257 engines directly - no special piston requirement for standard OEM or aftermarket pistons using a straight 23mm pin bore
• Wrist pin diameter is 23mm (0.905 in.) - verify aftermarket piston pin bore compatibility before pairing with custom piston kits
• The 15024-4 H-Tuff Series is a step above the standard 14024-4 H-Beam - same pin, bore, and length dimensions but with a heavier, thicker beam cross-section for greater strength at elevated boost and power levels
• The H-Tuff Plus variant (15024R6-4) is available separately with ARP Custom Age 625+ bolts for even higher load applications
• Rod bolt torque specification: 60 ft-lbs with 30wt oil; rod bolt stretch: 0.0058 in.-0.0062 in.
• Sold as a set of 4 rods
• Professional engine builder installation strongly recommended

Features

• H-Tuff Series - Manley's heavy-duty H-Beam design positioned between the standard H-Beam (14024-4) and the full Turbo Tuff I-Beam; incorporates a wider beam with increased cross-sectional thickness in critical areas for greater strength under sustained high-boost, high-power conditions
• Designed specifically for high-boost EJ20/EJ25 applications where the standard H-Beam's safety margin may be insufficient - ideal for aggressive street builds, time attack, and track day competition
• Manufactured from premium forged 4340 chromoly steel alloy to the same exacting standards developed and approved by Manley's original equipment customers
• Rated to approximately 750 HP at the flywheel / up to 600 wheel horsepower - a meaningful step above the standard H-Beam's ~600 crank HP rating
• Full heat treatment, stress relieving, shot peening, and magnafluxing applied to every rod for proven structural integrity and defect-free quality assurance
• Big end and wrist pin bores final honed to ±0.0002 in. tolerance for precision fit and consistent clearance across all four rods
• Bronze alloy small end bushing pressed into the wrist pin bore for improved wear resistance and long-term durability under high-load sustained operation
• Weight matched as a set to within ±1.5 grams for superior rotating assembly balance and reduced vibration at high RPM
• Critical bend and twist specifications tightly controlled throughout machining and final inspection
• Perfectly round big and small end bores verified through Manley's final inspection department
• Includes ARP 2000 3/8 in. cap screws - 220,000 PSI tensile strength for reliable rod cap clamping at high engine loads
• H-Tuff Plus variant (15024R6-4) available with ARP Custom Age 625+ bolts for maximum bolt-load applications

Specifications

• Rod Series: H-Tuff
• Material: Forged 4340 Chromoly Steel Alloy
• Center-to-Center Length: 5.137 in.
• Big End Bore Diameter: 2.165 in.
• Big End Width: 0.840 in.
• Wrist Pin Diameter: 0.905 in. (23mm)
• Pin Bore Diameter: 0.9063 in.
• Small End Bushing: Bronze Alloy (Pressed In)
• Bore Tolerance: ±0.0002 in. (big end and pin bore)
• Rod Weight: ~565 grams each
• Weight Matching Tolerance: ±1.5 grams per set
• Bolt Size: 3/8 in.
• Included Bolts: ARP 2000 Cap Screws (3/8 in.)
• Rod Bolt Torque Spec: 60 ft-lbs (with 30wt oil)
• Rod Bolt Stretch Spec: 0.0058 in.-0.0062 in.
• HP Rating: ~750 HP (flywheel) / ~600 HP (wheel)
• Quantity: Set of 4
• Application: Subaru EJ-Series (EJ205, EJ255*, EJ257)

Included Components

• 4x Manley H-Tuff connecting rods (forged 4340 steel, bronze bushed small end)
• 4x ARP 2000 3/8 in. cap screws (rod bolts)

Product Description

The Manley 15024-4 is the H-Tuff Series step up from the standard H-Beam 14024-4, engineered for Subaru EJ20/EJ25 applications where additional beam strength is required beyond what the standard H-Beam can provide. Sharing identical center-to-center length (5.137 in.), pin diameter (23mm), and bore dimensions with the 14024-4, the H-Tuff differentiates itself through a wider, heavier beam cross-section with increased material thickness in the critical midsection - delivering a meaningfully stronger rod rated to approximately 750 HP at the flywheel, versus the standard H-Beam's ~600 crank HP ceiling. This makes the 15024-4 the ideal rod for aggressive EJ builds running elevated boost levels, larger turbos, or track and time attack applications where the standard H-Beam's safety margin is insufficient but the cost and weight of a full Turbo Tuff I-Beam is not warranted.

Like all Manley EJ-series rods, the 15024-4 is machined from forged 4340 chromoly steel and subjected to full heat treatment, stress relieving, shot peening, and magnafluxing. Big end and pin bores are honed to ±0.0002 in. tolerance, and each set is weight-matched to within ±1.5 grams. A pressed bronze alloy small end bushing provides superior wrist pin wear resistance. ARP 2000 3/8 in. cap screws are included standard; builders seeking even greater bolt-clamping capacity can step up to the H-Tuff Plus variant (15024R6-4), which ships with ARP Custom Age 625+ fasteners. Rod bolt torque spec is 60 ft-lbs with 30wt oil, with a target stretch of 0.0058-0.0062 in.

The same EJ255 piston caveat from the standard H-Beam applies here: OEM EJ255 pistons (Forester XT, Outback XT, Legacy GT) use a tapered wrist pin bore that is mechanically incompatible with the straight small end bore of the 15024-4. These rods can only be used in EJ255 applications with aftermarket pistons that use a straight (non-tapered) pin bore. Confirm piston compatibility with your engine builder before ordering. Fitment covers the 2002-2014 Subaru WRX (EJ205), 2004-2021 STI (EJ257), 2004-2013 Forester XT, 2005-2009 Outback XT, 2005-2012 Legacy GT, and 2007-2009 Legacy GT Spec B. Professional engine builder installation is strongly recommended.