1. Pistons, Rings, Rods & Parts Engines Components For Sale
  2. sku: 12588267725151891
  3. BOOSTLINE 5137-905

BOOSTLINE 5137-905 Arp Connecting Rod Kit EJ20/EJ25 130.5MM 625

fits model: Ej25, Turbo. make: Subaru.

5137-905 Boostline Subaru Ej20/ej25 Turbo 130.5mm Arp 625 - Connecting Rod Kit

( Brand: Boostline ), ( Manufacturer Part Number: 5137-905 ), ( Type: Connecting Rod ), ( Material: Steel ), ( Vintage Part: No ), ( Performance Part: Yes )

Review BOOSTLINE Subaru Ej20/ej25 130.5mm Arp 625 Connecting Rod Kit fits EJ25 TURBO

The **Boostline 5137-905 Subaru EJ20/EJ25 Turbo 130.5mm ARP 625 Connecting Rod Kit** is a premium, high-performance upgrade designed specifically for enthusiasts seeking to maximize power, reliability, and durability in their turbocharged Subaru EJ-series engines. Engineered for the EJ20 and EJ25 platforms common in models like the WRX, STI, and Legacy Turbo this kit replaces the stock forged steel rods with a set of **aftermarket forged steel connecting rods**, featuring a **130.5mm (5.137-inch) bolt circle** to accommodate the increased stroke and torque demands of aggressive turbocharging setups. The rods are **ARP 625 bolted**, meaning they utilize **ARP 625-grade bolts**, which are among the strongest and most reliable in the aftermarket, capable of withstanding extreme loads without stretching or failing. This combination of **high-strength forged steel rods** and **ARP 625 bolts** ensures superior strength-to-weight ratio, reducing reciprocating mass while maintaining uncompromising rigidity, which translates to better power delivery, smoother operation, and enhanced longevity especially under heavy boost and high-RPM conditions.

Beyond its structural integrity, this kit is meticulously crafted for precision, with **close-tolerance machining** to ensure a perfect fit with the EJ20/EJ25 crankshaft journals, minimizing vibration and wear while maximizing efficiency. The rods are **fully balanced** to prevent any imbalance that could lead to excessive stress on the crankshaft or engine components, making them ideal for high-revving applications where smoothness and reliability are critical. Whether you're running a **stock or upgraded turbo setup**, a **nitrous oxide injection system**, or a **forced induction combination with a supercharger**, these rods provide the backbone needed to handle the increased stress without compromising on performance. Additionally, the **130.5mm bolt circle** is a key feature for those looking to push their engines beyond stock limits, as it allows for a longer stroke and greater displacement, further enhancing torque and power output.

For the serious Subaru builder, the **Boostline 5137-905 kit** represents a **critical step in building a durable, high-performance engine** capable of handling extreme modifications. Unlike stock rods, which are often weaker and prone to failure under heavy loads, these **forged steel rods with ARP 625 bolts** offer a **quantum leap in strength**, making them a staple in high-performance builds, drift applications, and even professional racing setups. The kit is backed by **Boostline s reputation for quality**, ensuring that every rod meets stringent manufacturing standards for consistency and performance. Whether you're restoring a classic EJ engine or building a modern turbocharged beast, this connecting rod kit is a **must-have upgrade** for anyone serious about pushing their Subaru s limits while maintaining reliability.

### **Pros and Cons of buying a Boostline 5137-905 Subaru EJ20/EJ25 Turbo 130.5mm ARP 625 Connecting Rod Kit**

#### **Pros**

1. **High-Quality Materials and Construction**

- The kit uses **ARP 625 bolts**, which are among the strongest and most reliable aftermarket connecting rod bolts available. They are forged from high-strength steel and feature a **625,000 psi tensile strength**, significantly exceeding OEM specifications.

- Boostline is a well-regarded brand in the turbocharging and engine-building community, known for durability and precision engineering.

2. **Increased Engine Reliability**

- The **130.5mm rod length** is a common upgrade for the EJ20/EJ25, offering a **lower rod-to-piston ratio** (RTR) compared to stock (which is 1.85:1). A lower RTR reduces **rod sideforce**, which can help prevent catastrophic failure in high-power applications, especially with forced induction.

- The **ARP bolts** eliminate the risk of bolt stretch or failure under extreme boost and RPM, which is a common issue with stock bolts in turbocharged builds.

3. **Compatibility and Ease of Installation**

- The kit is designed specifically for the **Subaru EJ20 and EJ25 engines**, ensuring proper fitment with stock crankshaft journals and rod bearings.

- Boostline provides **detailed installation instructions**, and the kit includes all necessary hardware (bolts, washers, and sometimes gaskets or seals), reducing the need for additional purchases.

4. **Performance Benefits**

- While the primary purpose is **reliability**, the lower RTR can also contribute to **better piston stability** at high RPM, potentially improving power output in turbocharged applications.

- Since the kit is often used in **high-boost builds**, it helps prevent rod bending or failure, allowing for more aggressive tuning without risking engine damage.

5. **Warranty and Support**

- Boostline offers **warranty coverage** on their products, providing peace of mind for serious builders.

- The brand has a strong reputation in the aftermarket, with widespread availability of parts and technical support.

---

#### **Cons**

1. **Cost**

- The **ARP 625 bolts alone are expensive**, and the full Boostline kit (including rods, bolts, and sometimes additional components) can be a significant investment, often **$300 $600 ** depending on the exact configuration.

- For a stock or mildly modified engine, this may be seen as an **overkill expense**, especially if the engine is not heavily stressed.

2. **Installation Complexity**

- Replacing connecting rods is a **major engine job** that requires **precision machining, proper torque specifications, and experience**.

- If not installed correctly, even high-quality rods and bolts can fail. This means the job should ideally be done by a **trusted machine shop or engine builder**.

- Some users may need to **machine new rod journals** on the crankshaft if the stock ones are worn, adding to labor costs.

3. **Potential Overkill for Mild Builds**

- If the engine is **not heavily turbocharged** (e.g., stock or low-boost applications), the benefits of this kit may be **minimal**, and the cost may not justify the upgrade.

- Stock rods and bolts can handle **moderate boost** (e.g., 10 15 psi) without issue, so this kit is more suited for **high-power applications (20 psi or high RPM builds)**.

4. **Limited Aftermarket Support for Rods**

- Unlike bolts, **aftermarket rods for the EJ20/EJ25 are rare**. Most builders either use **stock rods with ARP bolts** or **custom rods from specialty manufacturers**, which can be harder to source.

- The Boostline kit may include **stock-length rods** (if not the 130.5mm version), meaning the **130.5mm rods** might require additional machining or custom ordering.

5. **Potential for Over-Torquing Risks**

- While ARP bolts are forgiving, **improper torque application** (either too loose or too tight) can still cause issues.

- Some builders report that **ARP bolts can be tricky to torque correctly** due to their high strength, requiring **specialized torque tools** (e.g., torque wrenches with high precision).

---

### **Recommendation**

The **Boostline 5137-905 Subaru EJ20/EJ25 Turbo 130.5mm ARP 625 Connecting Rod Kit** is a **premium upgrade** best suited for **high-performance, turbocharged EJ engines** where reliability is critical. The **ARP 625 bolts alone make this kit one of the safest choices** for engines running **high boost (20 psi) or extreme RPMs**, significantly reducing the risk of catastrophic failure.

However, this kit is **not necessary for stock or mildly modified engines**. For those applications, **stock rods with ARP bolts** (or at least ARP bolts on stock rods) may provide sufficient reliability at a lower cost.

#### **Who Should Buy This Kit?**

**High-boost turbo builds (20 psi)** Especially if running **big turbos, aggressive tuning, or high RPMs**.

**Engines with a history of rod bolt failure** If stock bolts have already failed or are stretched.

**Builders prioritizing maximum reliability** Those who want the **absolute strongest rods and bolts** available.

**Engines with custom rod lengths (130.5mm)** If you re already running **shorter rods** for better RTR, this kit ensures those rods are secured properly.

#### **Who Should Avoid This Kit?**

**Stock or low-boost engines (under 15 psi)** The cost may not be justified for mild applications.

**Builders without proper machining experience** If you can t ensure **crankshaft journal integrity**, this kit won t help.

**Those on a tight budget** If money is a concern, **ARP bolts alone** (without full rod replacement) may be a more practical first step.

#### **Final Recommendation**

If you are **seriously modifying your EJ20/EJ25 with turbocharging and aiming for high power**, this kit is a **strong investment** in engine longevity. However, if your build is **mild or stock-based**, consider **ARP bolts alone** or **stock rods with upgraded bolts** first to save costs.

For the best results:

- **Have a trusted machine shop perform the installation.**

- **Ensure crankshaft journals are in good condition** (may require regrinding).

- **Follow torque specifications precisely** (ARP provides detailed guidelines).

- **Consider pairing with other reliability upgrades** (e.g., forged internals, upgraded oil system).

In summary, this is a **top-tier reliability upgrade** for **high-performance EJ engines**, but it s not a one-size-fits-all solution. Evaluate your build s power goals before committing.

Details:

BoostLine Subaru EJ20/EJ25 Turbo 130.5mm ARP 625 - Connecting Rod Kit.

part #: 5137905 price

  • $799.99

specifications pistonrinro:

  • for models: Ej25, Turbo
  • for makes: Subaru
  • brand: Boostline
  • mpn: 5137-905
  • type: Connecting Rod
  • material: Steel
  • vintage part: No
  • performance part: Yes

seller pistonrinro:

  • rating: 99.7%
  • city: Orlando, Florida
  • # reviews: 23590

general pistonrinro:

  • Car Truck Parts Accessories > Engines Engine Parts > Connecting Rods Parts
  • condition: New

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  • cost: $0.00
  • carrier: FedEx
  • type: Fixed
  • transit: 2-6 Days
  • class: Standard
  • service: FedEx Ground / FedEx Home Delivery

offer pistonrinro:

  • options: Ship-to-home
  • started: March 3, 2026
  • best offers: True
  • quantity: 2
  • sold: 0
  • availability: In Stock

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  • time: 30 Days
for models: ej25, turbo, for makes: subaru, type: connecting rod, vintage part: no, performance part: yes,
category: auto parts > car truck parts accessories > engines engine parts > connecting rods parts, material: steel, sku: 12588267725151891,
Boostline 5137-905 Is Similar To:
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5 offers $799.99–$799.99 USD
  • New. Offer #1 priced at $799.99 + $0.00 shipping estimate = $799.99* total. BoostLine rods are forged from premium 4340 steel and utilize a patented, three-pocket design, maximizing strength while minimizing rotating weight. BoostLine connecting rods are designed and built for the stressful demands of high-powered, forced induction and nitrous engines.FREE SHIPPING
  • New. Offer #2 priced at $799.99 + $0.00 shipping estimate = $799.99* total. BoostLine connecting rods are machined from premium 4340 forged steel and feature high-quality ARP 2000 bolts standard, with even stronger ARP 625+ Custom Age bolts available in sport compact applications.FREE SHIPPING
  • New. Offer #3 priced at $799.99 + $0.00 shipping estimate = $799.99* total. They contribute to improved engine response and power output, making them a popular choice for performance tuning projects.FREE SHIPPING
  • New. Offer #4 priced at $799.99 + $0.00 shipping estimate = $799.99* total. Part NumberSB . The BoostLine connecting rod is one of the first off-the-shelf rods designed to withstand 2000+ HP performance.FREE SHIPPING
  • New. Offer #5 priced at $809.75 + $0.00 shipping estimate = $809.75* total. FREE SHIPPING

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