Piranha Propellers OA4 OMC Hub Assembly | OMC/Evinrude/Johnson 90–290HP

Piranha Propellers OA4 — OMC Hub Assembly for Evinrude & Johnson 90–290HP Outboards

The Piranha Propellers OA4 Hub Assembly is the complete hub replacement unit for OMC, Evinrude, and Johnson outboards from 90HP through 290HP. The OA4 uses an aluminum core center hub over-molded with Piranha's high-strength aerospace composite, paired with the RCO4 rear cap that secures blades in the hub. Designed for Piranha's modular propeller system, the OA4 hub allows field blade swaps in minutes — no special tools, no tow back to the dock.

Part Specifications

• Part Number: OA4
• Hub Core: AO4 — aluminum core over-molded with high-strength aerospace composite
• Rear Cap: RCO4
• Replaces / Fits: OMC, Evinrude, Johnson outboards — see compatible engine list below
• Guarantee: Lifetime hub assembly guarantee

Assembly Includes:

• AO4 Center Hub
• RCO4 Rear Cap
• Grease
• Piranha Sticker
• Info Brochure
• Instruction Booklet

Compatible Engine Applications

• OMC: 130, 150, 170, 175, 185, 200, 205, 225, 230, 235, 240, 250, 260, 265, 270, 285, 290 HP
• Evinrude: 90, 100, 115, 120, 125, 130, 135, 140, 150, 155, 175, 185, 200, 225, 235, 250 HP
• Johnson: 90, 100, 105, 115, 120, 130, 140, 150, 155, 175, 200, 225, 250 HP

Serviceability Note

The OA4 hub is the serviceable foundation of Piranha's modular propeller system. When a blade is damaged in a prop strike, only the blade is replaced — the hub assembly stays on the shaft. The AO4 center hub's aluminum core provides the structural interface with the propeller shaft, while the aerospace composite over-mold protects against corrosion and absorbs vibration. The RCO4 rear cap is the retention component that locks blades into the hub during operation and releases for field swaps. If the hub itself sustains damage from a severe strike, the OA4 assembly replaces the entire hub unit without removing or replacing the prop shaft hardware.

Installation Notes

• Apply included grease to the hub bore and prop shaft splines before installation
• Seat the AO4 center hub fully on the prop shaft before installing blades
• Insert blades into hub slots, then secure with the RCO4 rear cap — cap should click/seat firmly
• Torque to your engine manufacturer's specification for prop nut retention
• Do not run dry or without blades installed — hub is designed for loaded operation only
• Confirm engine model and HP against the compatibility list above before ordering

Additional Information

• Vendor: Piranha Propellers
• SKU: OA4
• Product Type: Piranha Propellers Hub Kit
• Country of Origin: USA
• HS Code: 8487.90 (propeller parts and accessories — verify for your import classification)

Frequently Asked Questions

Q: What's the difference between the OA4 hub assembly and purchasing a full blade set?
A: The OA4 is the hub assembly — the center hub (AO4) and rear cap (RCO4) that mount on the prop shaft and hold the blades. Blade sets are purchased separately. If your hub sustained damage in a severe strike, order the OA4. If only the blades are damaged, order replacement blade sets that match your current pitch and diameter.

Q: Does this hub fit all Piranha blade series?
A: The OA4 is specific to the OMC/Evinrude/Johnson gearcase application. Confirm your blade series is compatible with the OA4 hub before ordering replacement blades — Piranha hub models are application-specific and not interchangeable across gearcase families.

Q: Is the hub included with Piranha blade sets, or do I need to buy it separately?
A: Piranha kits (Propulsion Kit, Performance Kit) include the hub assembly. If you are purchasing replacement blade sets only, the hub is not included — order the OA4 separately if you need a new hub.

Q: What does the lifetime hub assembly guarantee cover?
A: Piranha's lifetime guarantee covers the hub assembly (AO4 center hub and RCO4 rear cap) against manufacturing defects. It does not cover damage from prop strikes, improper installation, or operation without blades. Contact Piranha Propellers directly for warranty claims.

Q: Can I reuse the OA4 hub after replacing damaged blades?
A: Yes — that is the core advantage of Piranha's modular system. Unless the hub itself is visibly cracked or deformed from a severe strike, the OA4 hub assembly stays on the shaft and only the blades are swapped. Inspect the hub seat and rear cap retention for damage after any strike before returning to operation.