SKU: 301-8309
ARP M12 8740 Black Oxide 12-pt Nut Kit for Honda Civic Si Subaru WRX STI
ARP M12 8740 Black Oxide 12-pt Nut Kit delivers secure fastening for performance engine components like head studs. Fits M12x1.5 threaded applications in Honda K-series and Subaru EJ engines including Civic Si and WRX models. Built with 180,000 PSI tensile strength for reliable clamping under high boost and RPM.
Key Features
- 8740 Chrome Moly Steel: Forged construction rated at 180,000 PSI tensile strength to withstand extreme cylinder pressures and vibrations
- Black Oxide Finish: Resists corrosion and galling while allowing smooth torquing in engine bays
- 12-Point Head Design: Provides 12 contact points for positive grip using 19mm 12-point socket and better access around headers
- Thick Wall Profile: Maximizes rigidity and thread engagement without adding bulk for tight clearances
- 10 Nuts Per Kit: Complete set for cylinder head or main stud replacements on multi-cylinder engines
Product Notes
- Confirm M12x1.5 thread match with existing ARP studs before use
- Apply ARP thread lubricant during assembly for precise torque
- Packaged in protective tube to prevent damage during storage
Installation Notes
- Professional installation recommended.
- Torque to ARP specifications using calibrated torque wrench in sequence
- Direct replacement for OEM or stock nuts on ARP M12x1.5 studs
This Part Fits
| Year | Make | Model | Submodel |
|---|---|---|---|
| 2006-2011 | Honda | Civic | Si (K20Z3) |
| 2002-2006 | Acura | RSX | Type-S (K20A2) |
| 2004-2021 | Subaru | Impreza | WRX/STI (EJ25) |
| 2004-2009 | Subaru | Legacy | GT (EJ25) |
| 2004-2017 | Subaru | Forester | XT (EJ25) |
| 1999-2001 | Honda | Civic | Si (B16A2) |
Why Choose ARP?
- Trusted by NHRA and SCCA racers for decades in high-horsepower builds
- Every nut 100% inspected for thread accuracy and material integrity
- Precision CNC machined threads for consistent preload and sealing
Frequently Asked Questions
-
Q: What vehicles does this nut kit fit?
A: Designed for M12x1.5 ARP studs in Honda K20 B16 engines like Civic Si RSX and Subaru EJ25 in WRX STI Legacy GT Forester XT -
Q: What material and finish do these nuts have?
A: Made from 8740 chrome moly steel with black oxide coating for strength corrosion resistance and reduced friction -
Q: Is there a warranty on ARP nuts?
A: ARP provides lifetime warranty against defects in materials or workmanship when installed and used per instructions
Shipping & Handling
- Method: UPS Ground or USPS Priority
- Availability: In stock - ships same or next business day
- Packaging: Secure plastic tube in 4in x 3in x 1in box
- Weight: 0.10 lbs
ARP
ARP (Automotive Racing Products) is the world’s premier manufacturer of high-strength engine and driveline fasteners—head studs and bolts, main studs, rod bolts, and more—engineered and manufactured in-house from start to finish for race-proven reliability. With vertically integrated processes that include cold heading, machining, heat-treating, thread rolling after heat treat, and rigorous QA, ARP maintains aerospace-level certifications (ISO 9001 and AS9100) and validates every part for repeatable clamp load and fatigue resistance. Signature alloys such as 8740 chromoly, ARP2000, L19, and Custom Age 625+ deliver ultimate tensile strengths up to the super-alloy range, while ARP Ultra-Torque fastener assembly lubricant helps achieve consistent pre-load during installation. From street performance builds to professional motorsport programs, ARP fasteners provide precise fitment, superior metallurgy, and the durability needed to keep engines together at elevated cylinder pressures and...
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ARP Head Studs
ARP head studs replace factory head bolts with precision-machined threaded studs that provide more consistent and repeatable clamping force on the cylinder head gasket. Unlike head bolts that apply torque through both rotational and tensile forces, head studs allow the nut to be torqued concentrically on a stud that is already stationary, producing more even clamping load across the entire head gasket surface. Popular ARP Head Stud Applications ARP head studs are available for a wide range of performance and turbocharged engines including the Subaru EJ series, Honda K series and B series, Mitsubishi 4G63 and 4B11, Honda Civic and Integra, Toyota 2JZ-GTE, Nissan SR20DET and RB series, GM LS series, Ford Coyote and 5.0, and Dodge/Chrysler HEMI applications. ARP offers both 8740 chromoly and ARP2000 alloy head stud kits, with the ARP2000 material providing approximately 20 percent higher tensile strength for high-boost applications above 30 psi. Why are head studs preferred over head b...
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