Step-by-Step Guide to Building a High-Performance Subaru Short Block from Scratch

Subaru enthusiasts and car enthusiasts alike know the thrill of having a high-performing engine under the hood. The Subaru short block is a crucial component in creating that high-performance engine that every car enthusiast desires. Building a Subaru short block from scratch can be a daunting task, but with the right components, tools, and tips, it can be a satisfying and rewarding experience. In this article, we’ll guide you through the process of building a high-performance Subaru short block step-by-step, covering the necessary components, tools, and common mistakes to avoid.

Basics of Building a Subaru Short Block

Before diving into the building process, it’s essential to have a basic understanding of the Subaru short block’s components. The short block consists of the engine block, crankshaft, connecting rods, pistons, and bearings. These components work together to form the foundation of a high-performance engine.

Tools Required for Building a Subaru Short Block

Before getting started with the building process, it’s essential to have all the necessary tools. These tools include a torque wrench, bearing puller, piston ring compressor, dial bore gauge, micrometer, and assembly lube. Make sure to have all these tools on hand before starting the building process.

Step-by-Step Process of Building a Subaru Short Block

Now that we have a basic understanding of the components and tools required let’s dive into the step-by-step process of building a Subaru short block.

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Step 1: Disassembling the Original Engine

The first step in building a Subaru short block is disassembling the original engine. This process involves removing the bolts, connecting rods, crankshaft, and pistons.

Step 2: Preparing the Block

The next step is preparing the engine block. This process involves cleaning the block, checking for cracks, and honing the cylinders. It’s crucial to ensure that the blocks are clean and free from debris to ensure the new components work correctly.

Step 3: Installing New Pistons

After preparing the block, it’s time to install new pistons. Make sure to use a piston ring compressor to install the pistons correctly. The connecting rods also need to be resized to ensure proper fitting.

Step 4: Installing the Crankshaft

The next step is installing the crankshaft, which is one of the most critical components of the short block. It’s crucial to ensure that the crankshaft is installed correctly, as it can affect the engine’s balance and performance.

Step 5: Assembling the Short Block

The final step is assembling the short block by installing the bearings and connecting rods. It’s essential to use assembly lube to ensure everything runs smoothly. Once the short block is assembled, it’s ready for installation in your car.

Common Mistakes to Avoid

Building a short block can be a challenging task, and there are several common mistakes to avoid. One common mistake is forgetting to resize the connecting rods, which can affect the engine’s balance. Another mistake is not using assembly lube, causing friction and engine damage.

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Tips and Tricks

Here are some tips and tricks to ensure your Subaru short block is built correctly and performs to its full potential:

  • Always use new components to ensure the engine’s longevity and performance.
  • Double-check all measurements and torque specifications to avoid engine damage.
  • Take your time during the building process to ensure everything is installed correctly.
  • Keep track of all parts and their respective locations to avoid confusion.


Building a high-performance Subaru short block from scratch can be a rewarding experience for car enthusiasts. With the right components and tools, anyone can build a short block that performs to its full potential. By following the step-by-step guide, avoiding common mistakes, and implementing tips and tricks, you can rest assured that your engine will run smoothly and provide the performance you desire.

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Davis Bellew

As a Subaru owner and enthusiast, Davis has a deep understanding of the needs and concerns of Subaru drivers. He specializes in writing informative and engaging content about Subaru maintenance and repair, and his articles are always well-researched and easy to understand. When he's not writing, he enjoys hiking and photography.

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