Understanding Chevy and Subaru Long Blocks: What Every Car Enthusiast Should Know

When it comes to rebuilding or replacing an engine, two terms often dominate the conversation: short block and long block. While short blocks offer the bare essentials, long blocks come equipped with more components, making them the preferred choice for many mechanics and car owners alike. This article dives deep into the world of long block engines, with a special focus on Chevy long blocks and Subaru long blocks—two powerhouses in the American and Japanese automotive industries.

Whether you're restoring a classic Chevrolet or rebuilding a high-performance Subaru, understanding what long blocks offer, how they differ across manufacturers, and how to choose the right one can make or break your project.

What Is a Long Block Engine?

A long block engine is a fully assembled engine that includes several key components necessary for basic engine function. Compared to a short block—which generally only includes the engine block, crankshaft, rods, and pistons—a long block adds:

• Cylinder heads
• Camshaft(s)
• Valve train components
• Timing components
• Oil pump
• Gaskets and seals

This configuration makes long blocks a more comprehensive and cost-effective solution for engine replacements or upgrades. However, it does not include ancillary parts like the intake and exhaust manifolds, alternator, or fuel system components.

Chevy Long Block: An Icon of American Muscle

A Legacy of Power and Versatility

The Chevy long block represents a cornerstone of American automotive engineering. Chevrolet’s V8 small-block and big-block engines have powered everything from vintage Camaros and Corvettes to heavy-duty trucks and modern performance vehicles. The long block configuration simplifies engine swaps and rebuilds, especially for high-performance or restoration applications.

Common Chevy Long Block Variants

1.350 Small Block Chevy Long Block
One of the most popular engines in history, the 350 SBC long block is known for reliability, power, and ease of customization. It’s a staple in hot rods, muscle cars, and even boats.

2.LS-Based Chevy Long Blocks
The LS family revolutionized performance with aluminum blocks, fuel injection, and superior power-to-weight ratios. Examples include:

• LS1 (5.7L)
• LS3 (6.2L)
• LS7 (7.0L)

3.Big Block Chevy Long Blocks (BBC)
Engines like the 454 are favored in drag racing and heavy-duty trucks for their massive torque and displacement.

Benefits of Using a Chevy Long Block

• Plug-and-play performance
  Most long blocks are designed for easy installation, especially with crate engine options.
• Cost-effective rebuild alternative
  When the original engine has catastrophic damage, a long block offers a more economical solution than buying a full crate engine.
• High availability of aftermarket parts
  From Edelbrock heads to Holley carburetors, customizing a Chevy long block is easy and accessible.

Subaru Long Block: Precision in a Boxer Format

The Unique Boxer Engine Layout

A Subaru long block is fundamentally different in design from a Chevy long block. Subaru engines use a horizontally opposed "boxer" configuration, which results in a lower center of gravity and improved balance. This layout is integral to Subaru’s identity, enhancing handling in vehicles like the WRX, Forester, and Outback.

Popular Subaru Long Block Engines

• EJ Series (e.g., EJ205, EJ257)
  These turbocharged engines power performance models like the WRX and STI. Long block replacements are often used for upgrades or when rebuilding engines after head gasket failures—a known issue in early EJ engines.
• FA and FB Series
  These newer engines improve fuel economy, emissions, and reliability. Long blocks from the FA20 and FB25 lines are used in modern Subaru models like the BRZ and Legacy.
• EZ Series (H6 engines)
  Six-cylinder Subaru long blocks are found in larger vehicles like the Tribeca and Outback 3.6R.

Key Advantages of a Subaru Long Block

• Genuine OEM compatibility
  Subaru long blocks are often sold as OEM replacements, ensuring perfect fit and function.
• Ideal for turbo builds
  Enthusiasts frequently opt for upgraded long blocks when increasing turbo boost pressures.
• Pre-assembled for convenience
  Installing a long block simplifies the process of engine repair or modification.

When Should You Consider a Long Block Replacement?

Replacing an engine is a major decision. Here are situations when choosing a Chevy long block or Subaru long block is the right move:

• Blown engine: When catastrophic failure (e.g., thrown rod or cracked block) occurs.
• Restoration projects: For classic cars, a long block saves time and ensures accuracy.
• Performance upgrades: For turbo builds or high-power applications.
• Warranty needs: Many remanufactured long blocks come with warranties.
• Time-saving solution: Compared to rebuilding your engine from scratch.

How to Choose the Right Chevy Long Block

When shopping for a Chevy long block, keep these factors in mind:

1.Match the displacement and generation
Not all 350 engines are the same. Gen I, Gen II, and LS-based engines have different mounts and electronics.

2.Check the compression ratio
For performance, consider higher compression—but make sure it’s compatible with your fuel system.

3.Crate vs. remanufactured vs. used
Crate engines are new and often come with warranties. Remanufactured units are rebuilt to OEM or better specs. Used long blocks are cheapest but riskiest.

4.Emissions compliance
Make sure your long block is compatible with your local emissions regulations.

How to Choose the Right Subaru Long Block

Because of Subaru’s unique boxer layout, choosing the right long block is even more critical:

1.Engine code match
Subaru engines are identified by codes like EJ205 or FB25. Match exactly to avoid wiring or mounting issues.

2.Turbo vs. non-turbo
Internal components differ significantly. Don’t attempt to convert a non-turbo long block into a turbo one without extensive modifications.

3.JDM vs. USDM
Japanese Domestic Market engines are often used as replacements but may have different sensors or emissions equipment.

4.Verify head gasket upgrades
Make sure the long block includes the updated multi-layer steel (MLS) head gaskets—especially for EJ-series engines.

Installation Tips and Best Practices

Whether you’re installing a Chevy long block or a Subaru long block, follow these steps for success:

1.Inspect thoroughly
Check for shipping damage and verify all torque specs before installation.

2.Use new gaskets and seals
Don’t reuse old components, especially if the long block doesn’t include them.

3.Prime the oil system
Ensure oil has reached critical components before first start-up.

4.Break in properly
Follow manufacturer guidelines for break-in RPM and oil change intervals.

5.ECU reflash or tuning
Especially important for Subaru turbo models and performance Chevy swaps.

Conclusion

Both Chevy long block and Subaru long block engines provide convenient, reliable, and performance-oriented options for engine replacement and upgrades. While Chevy long blocks appeal to the muscle car and truck crowd with their raw power and infinite customization, Subaru long blocks cater to drivers who value precision engineering, AWD performance, and modern efficiency.

Choosing the right long block depends on your project goals, budget, and mechanical skill. Whether you're chasing quarter-mile times or building an all-weather daily driver, a high-quality long block can breathe new life into your vehicle.

FAQs

Q1: Can I install a Chevy long block myself?
Yes, with mechanical experience and proper tools. If not, professional installation is recommended.

Q2: Are Subaru long blocks compatible across all models?
No. Engine codes, turbo/non-turbo status, and ECU compatibility must match exactly.

Q3: What’s the average lifespan of a remanufactured long block?
With proper installation and maintenance, 100,000–150,000 miles is common.

Q4: Do long blocks come with a warranty?
Most reputable sellers offer warranties ranging from 12 months to 3 years.

Q5: Can I turbocharge a stock Subaru long block?
Not advisable unless the engine is designed for it (e.g., EJ205, EJ257). Otherwise, internal components may not withstand boost pressure.