SUBARU 491160 Dohc Cylinder Head Half Fhi Valvetrain Cam

( Manufacturer Part Number: 491160 ), ( Type: Cylinder Head ), ( Material: Aluminum )

Review SUBARU Dohc Cylinder Head Half Oem Fhi Japan Complete Valvetrain Cam fits EJ25

The **Subaru 491160 EJ25 16V DOHC Cylinder Head (FHI Valvetrain Cam)** is a meticulously engineered component designed for high-performance applications in the legendary EJ25 engine family, renowned for its reliability, durability, and adaptability across a wide range of automotive projects. This cylinder head is a critical assembly in the **EJ25 16-valve DOHC (Dual Overhead Camshaft) engine**, which powers everything from stock Subaru Outbacks and Legacy models to heavily modified turbocharged and naturally aspirated builds. Crafted from high-quality **cast aluminum alloy**, the head is precision-machined to exacting specifications to ensure optimal airflow, combustion efficiency, and thermal management, making it ideal for both daily drivers and serious performance enthusiasts.

The **FHI Valvetrain Camshaft** integrated into this cylinder head is a key differentiator, offering a refined balance between low-end torque and high-revving capability. The **FHI (Full Hydrolic Intake) design** eliminates the need for mechanical lifters, reducing friction, wear, and maintenance while delivering smoother valve operation across the entire RPM range. This feature is particularly advantageous for forced-induction applications, where consistent valve lash is critical to preventing valve float and maximizing efficiency. The **16-valve DOHC architecture** featuring two camshafts per cylinder bank provides precise control over intake and exhaust events, enhancing breathing and power delivery, whether the engine is running stock, mildly modified, or heavily tuned with turbocharging or nitrous oxide.

This cylinder head is fully compatible with **EJ25 engines** found in Subaru models such as the **WRX, STI, Legacy, Outback, Tribeca, and Forester**, making it a versatile upgrade for both stock and aftermarket builds. The **intake and exhaust ports** are designed for optimal airflow dynamics, with **large, smooth passages** that minimize turbulence and maximize volumetric efficiency. The **combustion chamber shape** is optimized for efficient fuel-air mixture distribution, reducing knock sensitivity and improving thermal efficiency critical factors for engines running higher compression ratios or boost levels. Additionally, the head is equipped with **high-quality valve seats and guides**, often upgraded with **hardened inserts** to withstand the stresses of forced induction, extended engine life, and aggressive tuning.

For performance applications, this cylinder head can be paired with **high-flow intake and exhaust manifolds**, **stiffer valve springs**, and **adjustable rocker arms** to further enhance responsiveness and power output. The **threaded spark plug holes** and **high-quality gasket surfaces** ensure a secure seal when installed, while the **precision-machined deck surface** guarantees a perfect fit with the cylinder block. Whether used in a **stock swap, turbocharged build, or supercharged application**, this cylinder head delivers the structural integrity and airflow performance necessary to push the EJ25 engine to its limits whether for street driving, track use, or high-performance applications.

For those seeking the ultimate in reliability and power, this **Subaru 491160 EJ25 16V DOHC Cylinder Head (FHI Valvetrain Cam)** is an essential component, blending Subaru s engineering heritage with the demands of modern performance tuning. Its **durable construction, precise machining, and compatibility with a wide range of modifications** make it a standout choice for enthusiasts looking to extract every ounce of potential from their EJ25-powered vehicle.

The **Subaru 491160 EJ25DOHC cylinder head half (FHI valvetrain cam)** is a popular aftermarket part for EJ25 engines, particularly in the **2001 2006 Subaru Outback, Forester, and Legacy** models. Below is a detailed breakdown of its pros and cons, followed by a conclusion and recommendation.

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### **Pros of the 491160 EJ25DOHC Cylinder Head Half (FHI Valvetrain Cam)**

1. **Performance Gains**

- The **FHI (Full Hairpin) valvetrain** is designed for higher RPM performance compared to the stock **L-valvetrain**, allowing for better airflow and reduced valve float at higher engine speeds.

- The **camshaft profile** is tuned for improved exhaust and intake flow, which can enhance horsepower and torque, especially in naturally aspirated (NA) applications.

- Many users report noticeable power gains, particularly in the **5,000 6,500 RPM range**, where the FHI valvetrain excels.

2. **Compatibility with Forced Induction**

- While the stock EJ25 is not naturally aspirated, the **FHI valvetrain is a common choice for turbocharged or supercharged builds**, as it handles higher RPMs and valve loads better than the stock setup.

- Some turbo setups (e.g., **1.5 2.0 bar boost**) benefit from the improved valve dynamics, though supporting modifications (e.g., stronger springs, retainers, and pushrods) are often required.

3. **Stock-Like Appearance with Performance Upgrades**

- The **cylinder head half retains the stock appearance**, meaning it can be used as a direct replacement without requiring major cosmetic changes.

- Unlike full head swaps (e.g., **EJ22 or EJ24 heads**), this part is easier to install and integrates seamlessly with the existing engine bay.

4. **Cost-Effective Performance Modification**

- Compared to a full head swap or engine rebuild, the **491160 is relatively affordable**, making it an attractive option for those looking to extract more power without a full overhaul.

- It is often **cheaper than aftermarket head swaps** (e.g., **EJ22 heads**) while still providing meaningful gains.

5. **Improved Valve Train Durability (Compared to Stock)**

- The **FHI valvetrain is more robust than the stock L-valvetrain**, particularly at higher RPMs, reducing the risk of valve float and improving longevity in performance applications.

- Some users report **reduced valve train noise** compared to stock, though this depends on supporting mods.

6. **Easy Installation**

- Since it is a **half-head swap**, installation is straightforward just remove the stock head, install the new half, and reassemble.

- No major engine modifications (e.g., block work) are required, making it a **DIY-friendly upgrade**.

7. **Popular in the Tuning Community**

- The **491160 is a well-documented and widely used part**, with extensive forums (e.g., **SubaruTech, Reddit, EJ25 forums**) providing installation guides, tuning tips, and troubleshooting advice.

- Many **ECU tuners (e.g., Link, Haltech, APEXi) have maps optimized** for this setup.

---

### **Cons of the 491160 EJ25DOHC Cylinder Head Half (FHI Valvetrain Cam)**

1. **Limited Low-End Torque**

- The **FHI cam profile is optimized for mid-to-high RPM**, which means **low-end torque may suffer** compared to stock or a more aggressive low-end cam (e.g., **EJ22 heads**).

- If your primary use is **towing, hauling, or low-RPM power**, the gains may not be as noticeable.

2. **Requires Supporting Modifications for Full Potential**

- **Stronger valve springs and retainers** (stock springs can fail under high boost or RPM).

- **Upgraded pushrods** (stock pushrods may bend under heavy loads).

- **Head gasket replacement** (some users report leaks if the head isn t properly bedded).

- **ECU tuning** (stock ECUs may not fully optimize for the new cam profile).

- Without these mods, **power gains may be modest**, and reliability could be compromised.

3. **Not a Full Head Swap (Limited Flow Benefits)**

- Unlike a **full EJ22 or EJ24 head swap**, the **491160 only replaces the cylinder head half**, meaning **intake and exhaust ports remain stock**.

- This **limits airflow improvements** compared to a full head swap, which can provide **significantly better flow** (especially on the intake side).

- If you re running **high boost (2.5 bar)**, a full head swap may be necessary to handle the increased airflow.

4. **Potential for Increased Oil Consumption**

- Some users report **higher oil consumption** with the FHI valvetrain, particularly if the **valve seals or guides wear out**.

- This is not universal but is something to monitor, especially in high-mileage or heavily modified engines.

5. **Not a Direct Drop-In for All EJ25 Engines**

- While the **491160 fits most 2001 2006 EJ25 engines**, **some minor adjustments may be needed** (e.g., **camshaft position sensor clearance, exhaust manifold fitment**).

- **Pre-2001 EJ25 engines (e.g., Legacy GT) may require additional modifications** due to differences in valve cover and camshaft position.

6. **Noise and Valvetrain Stress**

- The **FHI valvetrain is louder than stock**, especially at high RPMs, which some drivers find annoying.

- If not properly supported (e.g., **stronger springs, oil control rings**), **valvetrain wear can occur**, leading to **ticking or knocking noises**.

7. **Limited Longevity Without Upgrades**

- The **stock EJ25 is not built for high-performance use**, and the **FHI valvetrain alone may not be enough** for aggressive builds (e.g., **300 HP turbo setups**).

- Without **reinforced internals (crank, rods, pistons), a supporting head swap, and proper tuning**, the engine may **struggle with reliability** under heavy loads.

---

### **Conclusion**

The **Subaru 491160 EJ25DOHC cylinder head half (FHI valvetrain cam)** is a **solid mid-tier performance upgrade** for the stock EJ25 engine. It offers **noticeable power gains, especially in NA or lightly turbocharged applications**, while being **easier to install than a full head swap**. However, it is **not a magic bullet** its effectiveness depends heavily on **supporting modifications** (springs, pushrods, tuning) and **engine application**.

- **Naturally aspirated (NA) builds** looking for a **cost-effective power increase**.

- **Lightly turbocharged (1.5 2.0 bar) setups** where the **FHI valvetrain helps reduce valve float**.

- **DIY enthusiasts** who want a **relatively simple upgrade** without a full engine rebuild.

- **Drivers who prioritize mid-to-high RPM power** over low-end torque.

- **Heavy-duty towing or low-RPM applications** where low-end torque is critical.

- **Aggressive turbo builds (2.5 bar)** without a **full head swap and reinforced internals**.

- **Those who want maximum airflow** (a full EJ22/EJ24 head swap provides better flow).

- **People who dislike valvetrain noise** (the FHI setup is louder than stock).

---

### **Recommendation**

If you are looking to **extract more power from your stock EJ25** without a full engine overhaul, the **491160 FHI valvetrain cam is a great choice**, provided you are prepared for **additional supporting mods**. Here s how to approach it:

1. **Start with a Stock or Lightly Modified Engine**

- If your engine is **high-mileage or worn**, consider **rebuilding or replacing critical components (crank, rods, pistons)** before installing the FHI heads.

- If your engine is **stock or lightly modified (e.g., stock turbo, mild tune)**, the **491160 will provide noticeable gains** with minimal additional work.

2. **Upgrade Supporting Valvetrain Components**

- **Replace stock valve springs and retainers** with **aftermarket high-performance ones** (e.g., **JE, Tokico, or Subaru-specific upgrades**).

- **Upgrade pushrods** if running **high RPMs or boost** (stock pushrods can bend).

- **Check valve seals and guides** for wear, especially if the engine has high mileage.

Details:

Manufacturer Part Number: 491160 partial. Valve Configuration. Complete valvetrain included; camshafts, rocker arms, valve springs, retainers, and cam sprocket all intact present. Compatible Year Range.

Surface Finish. OEM Cast Aluminum. Who the heck doesn't eh. Compatible Make: Subaru.

Compatible model. Other Part Number: 13-1B / 7H69 025. Fire deck surface appears flat and crack-free. Shipping is FAST FREE.

Carbon deposits present on valves consistent with normal use. Gratitude is the greatest currency of all. Condition: Used. Type: Cylinder Head.

Placement on Vehicle. Displacement. Country of Manufacture. Sold used, as-is, and untested.

Bundle: Single Half Complete Valvetrain Included. Impress, Legacy, Forester, Outback. Casting codes: JAPAN / 13-1B 025. Very nice no seen cracks or deep scratches.

1996 2004 broad range. Number of Valves. Brand: Subaru. No Warranty Sold As-Is.

part #: 491160 price

• $240.00

specifications cylinderheapar:

• for models: Ej25
• for makes: Subaru
• mpn: 491160
• type: Cylinder Head
• material: Aluminum

offer cylinderheapar:

• availability: In Stock
• options: Ship-to-home
• started: April 23, 2026
• sold: 0
• best offers: True
• quantity: 1

seller cylinderheapar:

• rating: 99.6%
• # reviews: 584
• city: Gresham, Oregon

returns cylinderheapar:

• paid by: Seller
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• policy: Returns Accepted

payments cylinderheapar:

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general cylinderheapar:

• Car Truck Parts Accessories > Engines Engine Parts > Cylinder Heads
• condition: Used

shipping cylinderheapar:

• class: Standard
• service: USPS Ground Advantage
• type: Fixed
• transit: 4-8 Days
• carrier: USPS
• cost: $0.00

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