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The Subaru WRX STI is a beloved performance car, known for its rally heritage and impressive power. However, many enthusiasts seek to push the limits of their vehicles, aiming to increase the stock power from 300 horsepower to over 450 horsepower. Achieving this significant power boost requires careful planning and the right upgrades. In this article, we will explore how to effectively increase Subaru WRX STI power with upgraded internals.
Understanding the Basics of Engine Internals
Before diving into the upgrades, it’s essential to understand the components that make up the engine internals. The engine’s internals play a crucial role in determining its performance and durability. Key components include:
- Engine Block
- Pistons
- Connecting Rods
- Cylinder Head
- Crankshaft
Key Upgrades for Increasing Power
To achieve the desired power increase, several upgrades are necessary. Each component must be carefully selected to ensure compatibility and performance. Here are the key upgrades you should consider:
- Forged Pistons: Upgrading to forged pistons can handle higher boost levels and provide better durability.
- High-Performance Connecting Rods: Stronger connecting rods are essential to withstand the increased power and torque.
- Upgraded Crankshaft: A forged crankshaft can provide the strength needed for high horsepower applications.
- Aftermarket Cylinder Heads: High-flow cylinder heads can improve airflow, increasing power potential.
- Turbocharger Upgrade: A larger turbocharger can significantly boost horsepower by increasing air intake.
Choosing the Right Components
Selecting the right components is crucial to achieving the desired power levels. Here are some recommendations for each component:
Forged Pistons
Look for pistons designed for high-performance applications, such as those from reputable brands like JE Pistons or CP-Carrillo. Ensure they have the appropriate compression ratio for your setup.
Connecting Rods
Consider rods from brands like Manley or Eagle, which are known for their strength and reliability in high-horsepower builds.
Crankshaft
A forged crankshaft from companies like Brian Crower or Eagle can provide the necessary strength for your power goals.
Cylinder Heads
Aftermarket cylinder heads from brands like Cosworth or Tomei can improve airflow and performance. Ensure they are compatible with your turbocharger setup.
Turbocharger
Choose a turbocharger that matches your power goals. Brands like Garrett and BorgWarner offer options that can provide the necessary airflow to reach 450+ horsepower.
Supporting Modifications
In addition to upgrading internals, supporting modifications are essential for reliability and performance. Consider the following:
- Fuel System Upgrade: A high-flow fuel pump and larger injectors are crucial for supporting increased power.
- ECU Tuning: A proper tune is necessary to optimize performance and ensure the engine runs smoothly with the new components.
- Exhaust System: Upgrading to a high-flow exhaust system can help reduce back pressure and improve overall performance.
- Intercooler Upgrade: A larger intercooler can help keep intake temperatures down, improving performance and reliability.
Installation Process
Installing upgraded internals requires mechanical expertise. It is recommended to consult with or hire a professional mechanic who has experience with Subaru engines. The process generally involves:
- Removing the engine from the vehicle.
- Disassembling the engine to access internals.
- Replacing old components with upgraded parts.
- Reassembling the engine and reinstalling it in the vehicle.
- Performing a thorough inspection and tuning after installation.
Conclusion
Increasing the power of your Subaru WRX STI from 300 HP to 450+ HP is an ambitious but achievable goal. By upgrading the internals and making supporting modifications, you can unlock the full potential of your vehicle. Remember to choose quality components, consider professional installation, and ensure proper tuning for the best results. With the right upgrades, your WRX STI can become a true powerhouse on the road.