Brand New Subaru Wrx Sti B25 Cylinder Heads Pair Premium Aftermarket Bare Castings

Subaru WRX STI B25 Cylinder Head – Brand New Bare Casting

High-Strength Replacement for 2.5L DOHC Turbocharged Engines

Enhance the structural integrity and thermal capacity of your Subaru boxer engine with this premium, brand-new B25 bare cylinder head casting. Engineered specifically for the high-output EJ255 and EJ257 turbocharged platforms, this head is manufactured from a high-strength aluminum alloy designed to outperform original factory castings in high-boost environments. As a bare casting, it provides the ultimate technical flexibility for professional engine builders and racers to install custom-spec valves, high-rate springs, and aggressive camshaft profiles tailored to their specific performance goals.

Every B25 casting undergoes precision CNC machining to meet or exceed original equipment (OE) dimensional tolerances, ensuring absolute deck flatness for a superior head gasket seal—a critical requirement for preventing failures under forced induction. By starting with a “zero-hour” brand-new casting, you eliminate the risks of micro-cracking, combustion chamber fatigue, and warped surfaces common in used or remanufactured EJ-series heads. Whether you are building a 500+ HP time-attack engine or a reliable street-tuned STI, this reinforced B25 head provides the durable foundation and optimized cooling jackets necessary for sustained high-performance operation.

🛠️ In-House Machining Process

• Debris-Free Preparation: Every new casting is chemically cleaned and blown out to remove all residual machining oils, metal shavings, and manufacturing debris. This ensures your oiling system remains uncontaminated from the first start-up.

• In-House Precision Machining: Unlike “shelf-stock” heads, we perform all final machine work in-house. This includes final guide sizing and precision valve seat cutting to ensure perfect geometry and clearances before the head reaches the assembly bench.

• Pressure & Integrity Testing: To go beyond the factory standard, we pressure-test every head to 60 PSI. This verifies that the casting is free of porosity leaks or internal defects that could compromise the cooling or oiling systems.

• Dimensional Inspection: Our technicians perform a multi-point inspection of the gasket-sealing surface and bore alignment. This ensures the head is perfectly flat and meets tight OEM tolerances for a flawless fit.

• Professional Assembly & Setup: Valvetrain components are installed and verified in a clean-room environment. We check spring heights and seal seating to ensure the assembly is balanced and ready for high-performance use.

• Vacuum-Seal Verification: Every intake and exhaust port is Vacuum Tested. This guarantees a 100% airtight seal between the valves and seats, ensuring maximum compression and peak performance right out of the box.

🛠️ Engineering & Performance Features

• Superior Durability: Advanced metallurgical construction provides better resistance to thermal stress and cracking than OEM units.
• Bare Casting Flexibility: Perfect for custom builds; allows for personalized selection of valvetrain components.
• Precision Machining: Laser-designed for a seamless, exact fit on 2.5L DOHC turbo blocks.
• Quality Assured: Every casting is thoroughly inspected and pressure tested to ensure zero defects in the water jackets or oil passages.

📊 Technical Specifications

• Engine Type: Subaru 2.5L DOHC Turbocharged (EJ25)
• Casting Designation: B25
• Condition: Brand New Aftermarket
• Format: Bare Casting (No internal components included)

🚛 Fitment Data

Compatible with 2.5L DOHC Turbocharged Models:

• Subaru Impreza WRX STI: 2004–2005
• Subaru Forester XT: 2004–2005
• Subaru Baja Turbo: 2004–2005
• Subaru Legacy GT: 2005–2006