The FA20 engine has a reputation, and it's a complicated one. Some see a fragile platform, while others see a powerhouse waiting for the right touch. Here's the secret: both are right. A poorly planned build is a recipe for disaster, but a professionally assembled one is a different beast entirely. If you're looking for an 'fa20 engine for sale', your goal isn't just horsepower—it's reliable horsepower. This guide is your roadmap to achieving impressive and consistent FA20 engine performance by addressing common failure points with the right parts from the start.
Key Takeaways
- Match the Engine to Your Ambition: Decide if you need a reliable daily driver, a spirited street car, or a track machine. This choice dictates whether you need a stock OEM replacement, a Stage 2 build with stronger internals, or a fully built motor designed for maximum power.
- Prioritize Forged Internals for Power: The stock FA20 connecting rods are the first thing to fail when you add significant power. Before chasing horsepower numbers, invest in a professionally built short block with forged components to create a durable foundation that can reliably handle the extra stress.
- Demand Documentation and a Warranty: A reputable engine comes with proof. Always require a complete build sheet, service records, and parts receipts to verify its quality. A clear warranty protects your investment and is a sign of a trustworthy builder.
Your Guide to the FA20 Engine
If you’ve spent any time in the Subaru world, you’ve definitely heard of the FA20. This 2.0-liter, four-cylinder boxer engine is a modern powerhouse found in some of Subaru's most popular performance models from 2012 onward. As the successor to the legendary EJ series, the FA20 brought new technology to the table, including direct injection, which set a new standard for efficiency and power potential.
The "boxer" design is a Subaru hallmark. It places the cylinders horizontally, so the pistons move toward and away from each other like a boxer throwing punches. This layout gives the engine a flat, low profile, which helps create a lower center of gravity for your vehicle. The result is improved stability and handling, whether you're carving up a canyon road or navigating a tight autocross course. For enthusiasts, the FA20 represents a fantastic platform for building a responsive and capable car, with a massive aftermarket community dedicated to pushing its limits.
Breaking Down FA20 Specs and Performance
The FA20 engine is known for its versatility, appearing in two primary forms. The naturally aspirated version, the FA20D, is found in the Subaru BRZ and its Toyota/Scion siblings. It produces around 200 horsepower and is celebrated for its sharp throttle response and high-revving nature. The second variant is the turbocharged FA20F, also known as the FA20 DIT (Direct Injection Turbo), which powers the WRX. This version delivers a more aggressive 268 horsepower from the factory and offers a huge ceiling for performance gains through engine tuning services and bolt-on modifications. Both engines share the same 2.0-liter displacement and square bore/stroke dimensions, creating a balanced foundation for reliable power.
Understanding the FA20's Unique Characteristics
Every engine has its own personality, and the FA20 is no exception. While it's a fantastic platform, it comes with a few well-known quirks right out of the box. Understanding these characteristics is the first step toward building a reliable and powerful machine. Instead of seeing them as flaws, think of them as opportunities for improvement. Addressing these specific traits with the right modifications is what separates a standard build from a truly dialed-in performance car. Let's look at the key behaviors you should know about before you start planning your upgrades.
The Mid-Range Torque Dip and Low-End Power
One of the most common complaints about the stock FA20 is its mid-range torque dip. This is a noticeable drop in power that occurs in the middle of the RPM range, right when you expect the car to keep pulling hard. It can make acceleration feel a bit flat and unresponsive, especially at lower speeds or when you're trying to power out of a turn. This dip is largely a result of the factory tuning and exhaust manifold design. The good news is that it's entirely correctable. With professional engine tuning services and carefully selected parts, you can smooth out that power curve and achieve a much more linear and satisfying acceleration.
"Knock Limited" Performance
The FA20 is often described as being "knock limited." This means the engine's computer (ECU) is programmed to be highly sensitive to engine knock, or detonation, and will quickly reduce power to prevent damage. While this is a crucial safety feature, it can also limit performance, particularly in warmer weather or under heavy load. This sensitivity is a key reason why reliability concerns, like rod knock, can arise if the engine is pushed too hard without the right supporting mods. Building a resilient engine means installing high-quality performance parts that create a stronger foundation, allowing for a more aggressive tune without compromising the engine's long-term health.
FA20 vs. FA24: An Evolution in Performance
For those considering a newer Subaru, it’s helpful to compare the FA20 with its successor, the FA24 engine found in the second-generation BRZ and current-gen WRX. Many enthusiasts see the FA24 as a significant improvement, as it largely resolves the torque dip and other issues associated with its predecessor. Subaru clearly applied lessons learned from the FA20 to create a more refined and potent engine from the factory. This doesn't mean the FA20 is obsolete; rather, it highlights the importance of choosing the right platform for your goals. A properly built FA20 can still deliver incredible performance, especially with targeted Subaru WRX upgrades designed to overcome its stock limitations.
Which Subaru Models Have the FA20?
The FA20 engine was a key player in Subaru’s lineup for nearly a decade. You’ll find the turbocharged FA20F engine in the 2015–2021 Subaru WRX and the 2014–2018 Forester XT. These models benefit from the engine's low-end torque and tuning potential, making them incredibly popular platforms for modification. If you're looking for Subaru WRX upgrades, the FA20F provides an excellent starting point. The naturally aspirated FA20D is the heart of the 2013–2020 Subaru BRZ, as well as the Scion FR-S and Toyota 86. Its lightweight and balanced design make these coupes some of the most engaging driver's cars on the market.
Where Can You Buy an FA20 Engine?
Once you’ve decided to get a new FA20, the next step is figuring out where to source it. Your choice will depend on your performance goals and budget. You can find everything from a standard OEM replacement to a fully built motor designed for the track. Each option has its pros and cons, so it’s important to know what you’re looking for before you start shopping. Let’s break down the three main places you can find an FA20 engine for your Subaru.
Sourcing from a Specialist: Crawford Performance
If you’re aiming for serious power and reliability, a professionally built motor is your best bet. We specialize in creating high-performance engines ready for demanding applications. Our built FA20 short block is engineered specifically for boosted setups in BRZ, FR-S, or GT86 models, capable of handling up to 660 horsepower. This isn't just a replacement; it's a foundation for a high-performance build. By choosing a built motor, you get a professionally assembled engine with upgraded components designed to withstand the stresses of increased power, saving you the guesswork and potential pitfalls of building it yourself.
Searching Online Marketplaces and Retailers
For those looking for a wider selection or a used engine, online marketplaces can be a valuable resource. Platforms like eBay offer a huge variety of FA20 engine options from different sellers, including used OEM motors, JDM imports, and sometimes even rebuilt units. The main advantage here is the ability to compare prices and potentially find a great deal. You can often find engines with low mileage pulled from donor cars. However, it’s crucial to do your due diligence. Carefully vet the seller, check their ratings, and read the entire description to understand exactly what you’re buying and what kind of warranty, if any, is included.
Buying New from an Authorized Subaru Dealer
If you need a brand-new, factory-spec engine, your most reliable source is an authorized Subaru dealer or a reputable OEM parts supplier. This route guarantees you get a genuine part that is a perfect match for your vehicle. For example, you can find an OEM FA20 DIT Turbo Short Block designed specifically for 2015-2021 WRX models. While this is often the most expensive option, it provides peace of mind knowing the engine is new and meets Subaru's exact standards. This is the ideal choice for a stock replacement or for someone who wants a fresh, reliable starting point for a mild build.
How Much Does an FA20 Engine Really Cost?
The price of an FA20 engine can vary dramatically depending on what you’re looking for. Costs range from a couple of thousand dollars for a used motor to well over five thousand for a high-performance build. Your budget and power goals will be the biggest factors in determining the final price tag. Whether you need a simple OEM replacement or a fully built engine ready for the track, understanding the different price points is the first step in making a smart purchase. Let's break down the typical costs you can expect for new, used, and performance-built FA20 engines.
The Price Tag on a New OEM Engine
If you're looking for a direct, factory-spec replacement, a new OEM (Original Equipment Manufacturer) engine is your most straightforward option. This ensures you get a brand-new motor built to Subaru's exact standards. For example, a new Subaru FA20 DIT Turbo short block for a 2015-2021 WRX typically costs around $2,700. While this is a significant investment, it provides peace of mind with factory reliability. Keep in mind this price is often for the short block alone, meaning you'll still need to account for the cylinder heads, other components, and labor costs to complete the installation.
Costs for Used vs. Rebuilt Engines
For those working with a tighter budget, the used and rebuilt market offers more accessible price points. You can find a wide range of used FA20 engines on online marketplaces, with prices varying based on mileage, condition, and what’s included. While you might find a complete used engine for less than a new OEM short block, this route requires careful vetting. A rebuilt engine can be a solid middle ground, but the quality depends entirely on the builder. Always scrutinize the seller's reputation, ask for a detailed history, and understand the warranty terms before committing.
Budgeting for Your Performance Build
When your goal is to push past stock power levels, a purpose-built engine is a necessary investment. A standard FA20 has its limits, but a professionally built short block can reliably handle over 600 horsepower. Expect to invest between $5,000 and $6,000 for a pre-built short block designed for high-power applications. This price reflects the cost of forged internals, precision assembly, and the engineering required to handle serious boost. This is more than just a purchase; it's an investment in durable performance parts that will protect your vehicle when you push it to its limits.
Planning for Lead Times and Unexpected Costs
The price of the engine itself is just the starting line. To build a reliable performance car, you need to budget for the entire ecosystem of parts that support it. This includes an upgraded fuel system, a capable turbo, and a robust cooling system to manage the extra heat. Beyond the parts, you must account for professional installation and, most importantly, a proper tune. A skilled tuner will ensure all your new components work together safely and efficiently, which is why professional engine tuning services are non-negotiable. Also, be prepared for potential "core fees"—a refundable deposit you pay for your old engine block—and the wait times, or "lead times," for custom parts. A professionally built engine often takes two to four weeks to be completed, so plan your project timeline accordingly.
The Importance of Documenting Your Build
Treat your build like a long-term investment and keep meticulous records of everything. Create a folder or digital file with every part number, receipt, and service record. This documentation is invaluable for future maintenance, making it easier to order the right parts or troubleshoot any issues that arise down the road. If you ever decide to sell your car, a comprehensive build history is one of the most powerful tools you have. It proves the quality of the work and the components used, which can significantly increase the vehicle's resale value. A reputable engine builder will always provide proof of their work, so be sure to request a complete build sheet that details every component and measurement used in your engine.
What to Look For When Buying an FA20
Once you’ve decided on a budget, the real search begins. Finding the right FA20 isn’t just about price; it’s about getting a solid foundation for your performance goals. Whether you're buying a used OEM engine or a fully built motor, paying close attention to the details will help you make a smart investment and avoid costly surprises down the road. A thorough evaluation of the engine's history, the seller's policies, and its compatibility with your car is essential. Think of it as a pre-purchase inspection for the heart of your Subaru.
Inspecting an Engine's Condition and Mileage
The history of an engine tells a story, and mileage is a key chapter. You’ll find used FA20s with a wide range of mileage, from under 10,000 to over 75,000. For a simple drop-in replacement, lower mileage is generally safer. However, if you’re planning a full performance build, a higher-mileage engine can be a cost-effective starting point since you’ll be replacing the internal components anyway. The most important thing is to get a clear history and assess the overall condition. A well-maintained engine with higher mileage is often a better bet than a low-mileage one that was abused or poorly maintained.
Don't Skip the Fine Print: Warranty and Returns
Never complete a purchase without understanding the seller’s warranty and return policy. Many private sellers or online marketplaces offer limited protection, sometimes as short as 30 days, and may charge a hefty restocking fee for returns. This is where buying from a reputable builder makes a difference. For example, we stand behind our work with a comprehensive 12-month/12,000-mile warranty on our built engines. This kind of guarantee provides peace of mind and protects your investment, ensuring you receive a motor that’s ready for the demands of high-performance driving and reflects the quality of the build.
Will This FA20 Fit Your Subaru?
Not all FA20 engines are created equal. The FA20DIT found in the 2015-2021 WRX is a direct-injected turbo engine, while the FA20D in the BRZ/FR-S/86 is naturally aspirated with a different fuel system and compression ratio. It is critical to confirm that the engine you’re buying is the correct variant for your specific model. Always double-check part numbers and consult with the seller to ensure compatibility. An incorrect engine can lead to major installation headaches and performance issues. If you have any doubts, it’s always best to consult with experts who specialize in Subaru WRX upgrades and other models.
Factoring in Shipping and Post-Delivery Inspection
An engine is a large, heavy, and sensitive piece of equipment, so logistics matter. Before buying, confirm shipping costs and timelines. When the engine arrives, inspect the crate for any external damage before you sign the delivery receipt. Once you accept it, immediately uncrate the engine and check for any signs of damage that may have occurred in transit, like cracks in the block or broken sensors. Take photos of everything. Most sellers have a short window for reporting shipping damage, so you need to act quickly. Planning for a smooth delivery and thorough inspection ensures you can address any issues right away.
Stock vs. Performance: Which FA20 Build is for You?
Deciding on a new FA20 engine isn't just about replacing a part; it's about defining your Subaru's future. The path you choose depends entirely on your goals, your budget, and how you plan to use your car. Are you looking for a reliable daily driver, a spirited weekend car, or a dedicated track machine? Each goal requires a different approach to the engine build. Thinking through your needs now will save you from potential headaches and extra costs down the road. Let's break down the three main paths you can take, from a simple factory replacement to a fully built powerhouse. Understanding these options will help you invest in an engine that perfectly matches your driving ambitions and gives you confidence every time you turn the key.
Option 1: The Stock OEM Replacement
If your primary goal is to restore your Subaru's factory performance and reliability, an OEM replacement is your most direct route. This option is perfect for daily drivers or for owners who were perfectly happy with the stock power levels before their original engine failed. The Subaru FA20 engine was engineered for a great balance of efficiency and performance right out of the box. Choosing an OEM replacement means you get a known quantity—an engine built to the manufacturer's exact specifications, ensuring a seamless fit and predictable behavior. It’s the simplest way to get your car back on the road without introducing the complexities and costs of performance modifications.
Option 2: Stage 1 & 2 Performance Builds
For the enthusiast who wants more power without sacrificing everyday usability, a Stage 1 or Stage 2 build is the ideal middle ground. This approach involves strengthening the FA20's known weak points by replacing factory components with durable, aftermarket performance parts. Typically, this means upgrading the stock pistons and connecting rods to forged alternatives that can safely handle more power. A well-executed Stage 2 build can reliably push your WRX or BRZ into the 400-450 horsepower range, transforming your driving experience. This is the perfect choice for spirited street driving and occasional track days, offering a significant performance gain while maintaining a degree of civility for regular use.
Option 3: The Fully Built High-Performance Engine
When maximum performance is the only thing that matters, a fully built, high-performance engine is the ultimate solution. This path is for serious competitors and enthusiasts building a dedicated track or race car. A professionally constructed FA20 short block can handle over 600 horsepower, but achieving that number reliably is the real goal. A true performance build is about more than just a peak horsepower figure; it’s about creating a robust, balanced system that can withstand extreme stress lap after lap. This requires meticulous assembly, top-tier components, and precise engine tuning services to ensure the entire package works in harmony, preventing costly failures when you’re pushing the limits.
Setting Realistic Power Goals
Before you spend a single dollar, it’s crucial to define what you want to achieve. Your power goals will dictate every decision you make, from the parts you choose to the type of build you need. Being honest about your expectations and understanding the engine's capabilities will set you up for a successful and reliable build, helping you avoid the common pitfalls that lead to engine failure.
Stock Block Limitations: 350-400 HP
The stock FA20 engine is a capable performer from the factory, but it has a well-documented ceiling. For most FA20s, the reliable limit on a stock block is between 350 and 400 horsepower. The primary weak point is the connecting rods, which were not designed to handle the stress of significantly increased power. Pushing past this threshold without upgrading the engine’s internals is a major gamble. While you might see higher numbers on a dyno sheet temporarily, you are drastically increasing the risk of catastrophic engine failure. Think of 400 HP as the absolute red line for a stock block if you value longevity.
Built Block Potential: 500+ HP
If your ambitions go beyond 400 horsepower, a built engine isn't just an option—it's a necessity. A professionally assembled FA20 with forged internals completely changes the equation. By replacing the stock pistons, rods, and other key components with high-strength performance parts, the engine’s foundation becomes strong enough to handle immense power reliably. A properly built FA20 can comfortably handle over 600 horsepower, transforming your Subaru into a true performance machine. This approach moves beyond just chasing peak numbers and focuses on creating a durable, resilient powerhouse that can withstand the demands of the street or track.
Build vs. Buy vs. Swap: Choosing Your Path
Once you have your power goals in mind, you’re faced with a fundamental choice: how will you get there? You can build the engine yourself, buy a professionally pre-built motor, or consider swapping in a different engine altogether. Each path has its own set of costs, benefits, and challenges. Your technical skill, budget, and timeline will all play a role in determining the best route for your project.
DIY Build vs. Professional Pre-Built Engines
Building an engine yourself offers complete control over every component, which can be a rewarding experience if you have the expertise and tools. However, it can also be a path filled with hidden costs, unexpected delays, and a steep learning curve. A single mistake during assembly can be catastrophic. In contrast, buying a professionally built engine offers a fixed price and the assurance of expert assembly. It costs more upfront, but it eliminates the guesswork and comes with a warranty, which is your single best protection. This is why professional engine tuning services are so critical—they ensure all those high-quality parts work together perfectly.
Rebuilding the FA20 vs. an Engine Swap
For those chasing big power, the idea of an engine swap—like dropping in an FA24—can be tempting. However, a swap is rarely a straightforward process. It often involves complex custom fabrication, wiring harness modifications, and ECU compatibility issues that can quickly spiral in cost and complexity. Rebuilding your existing FA20 is often a more direct and cost-effective solution. You can achieve incredible power levels with a built FA20 while retaining a factory-like fitment, avoiding the headaches of a custom swap. For most owners, investing in a robust build for their current platform provides the best balance of performance, reliability, and practicality for their Subaru WRX upgrades.
FA20 Engine Problems: What to Watch Out For
Every engine platform has its own set of quirks, and the FA20 is no different. Knowing what to watch for can save you a lot of headaches and help you make a smarter purchase. Whether you're buying a used stock motor or a fully built performance engine, understanding these common issues will prepare you for ownership and help you identify a solid investment. Think of this as your pre-flight checklist before you commit. A well-maintained and properly modified FA20 is a fantastic powerplant, but a neglected one can become a project you didn't sign up for. Let's go over the key areas to pay attention to so you can buy with confidence and get the most out of your Subaru.
The Deal with Oil Consumption and Carbon Buildup
One of the most talked-about issues with the FA20 is its tendency to consume oil, particularly when driven hard. It's critical to keep a close eye on your oil levels between changes to prevent running low, which can lead to serious engine damage. This oil consumption can also contribute to carbon buildup on the intake valves, a common trait of direct-injection engines. Over time, this can restrict airflow and reduce performance. Installing a quality Air/Oil Separator is one of the best preventative performance parts you can add to mitigate both of these issues, keeping your engine cleaner and running more efficiently.
Understanding the FA20's Weaker Internals
The stock FA20 engine is reliable for daily driving, but its connecting rods are a known weak point when you start adding significant power. If you’re planning for major horsepower gains, upgrading the factory internals is not just a suggestion—it’s a necessity. There's a common misconception that built FA20 engines are fragile. However, when they are properly maintained and constructed with quality forged parts, they can perform reliably and handle substantial power. Investing in a professionally built short block with forged rods and pistons is the foundation for any serious Subaru WRX upgrade plan, ensuring your engine can handle the extra stress from a larger turbo and aggressive tune.
Don't Forget the Transmission
It’s easy to get caught up in chasing horsepower numbers, but all that power is useless if you can't get it to the ground. A strong engine requires equally strong supporting systems, and the stock transmission is often the first component to protest when you add significant power. Think of your car's drivetrain as a chain; the engine is just one link. If you're planning a build that pushes past factory limits, you must also budget for an upgraded clutch or stronger transmission parts. Neglecting this critical step can lead to a frustrating and expensive failure, leaving your powerful new motor with no way to move the car. Ensuring your entire drivetrain can handle the new output is a core part of a successful performance build.
Red Flags When Buying a Used Engine
When you're looking at a used FA20, especially one that's already been modified, proceed with caution. A major red flag is a seller who can't provide a detailed service history or receipts for performance work. Be wary of the idea that a built motor doesn't require careful maintenance; it often requires more. Inspect the engine for any signs of oil leaks, coolant residue, or sludge under the oil cap. Ask about its history, who built it, and who tuned it. A vague answer is not a good sign. Proper engine tuning services are essential for engine health, so an unknown or questionable tune can be a deal-breaker.
How to Verify an FA20's Quality Before You Buy
When you’re investing in a performance engine, you need to do more than just kick the tires. Verifying the quality of an FA20, especially a built motor, requires a close look at its history, components, and the terms of the sale. A shiny engine block can hide a multitude of problems, so your best tools are documentation and a healthy dose of skepticism. A well-documented engine from a reputable builder will always be a safer bet than a mystery motor with a verbal-only history.
The goal is to find an engine that was built correctly and cared for meticulously. This means digging into the paperwork, understanding its service history, and clarifying every detail of the transaction before any money changes hands. Taking these steps protects your investment and ensures you get the reliable power you’re paying for. A great build is a combination of quality parts, expert assembly, and diligent maintenance, and it’s your job as the buyer to verify all three.
Your Pre-Purchase Checklist: Inspections and Paperwork
There’s a common misconception that built FA20s are fragile, but this isn't true if they are properly maintained and assembled with quality components. The proof is in the paperwork. When evaluating an engine, ask the seller for a complete build sheet that lists every single component used, from the pistons and rods to the bearings and head studs. This document is your primary tool for verifying the quality of the internal performance parts.
Beyond the build sheet, request receipts for the parts and any machine work performed. This confirms the components are what the seller claims they are and shows that the work was done by a professional shop. If the engine has been run, ask for dyno sheets, which provide a real-world look at its performance and the stability of the tune. An organized seller with comprehensive documentation is usually a sign of a well-cared-for engine.
Why Service and Maintenance Records Matter
Careful maintenance is crucial for the longevity of any FA20 engine, and a performance build demands an even higher level of attention. A thorough review of service records gives you insight into how well the engine has been cared for since it was built. You’re looking for a consistent history of oil changes with high-quality synthetic oil, regular fluid checks, and a log of any adjustments or repairs.
Ask for receipts from shops or a detailed log if the owner performed the maintenance themselves. An engine with a spotty or non-existent service history is a major red flag. This history also tells you if the engine received professional engine tuning services, which are essential for ensuring a built motor runs safely and reliably. Don’t just take the seller’s word for it; documentation is the only way to confirm the engine’s past.
How Do Core Exchanges and Returns Work?
When buying a built engine from a professional builder, you’ll likely encounter a core charge. Some builders require a deposit (the core fee) for your old engine block, which is refunded once you send it back. It's important to clarify this before purchasing to avoid any surprise costs. Ask the seller for the exact terms of the core exchange. How long do you have to return your old engine? What condition must it be in to receive a full refund?
You should also find out who is responsible for the shipping costs of the core, as this can be a significant expense. Understanding these details ensures a smooth transaction and helps you budget accurately for your new engine. A reputable builder will have a clear and fair core policy, so don't hesitate to ask for all the details upfront.
Top Upgrades for FA20 Engine Performance
The stock FA20 is a solid engine, but if you’re looking for serious power, you’ll need to go beyond the factory setup. A successful build isn’t about slapping on the biggest turbo you can find; it’s about creating a balanced system where every component works together to achieve your goals. A thoughtful approach ensures your engine is not only powerful but also reliable for the long haul, whether you're carving corners on the track or navigating a remote trail. To get the most out of your FA20, you need to address its limitations in three key areas: the engine internals, the fuel and air delivery systems, and the cooling system. Each of these areas builds upon the last, creating a strong foundation for dependable performance. Neglecting one area while focusing on another is a recipe for disaster, leading to premature wear or catastrophic failure. By upgrading these systems strategically, you can transform your Subaru into a finely tuned machine that delivers consistent power when you demand it. We have a wide selection of performance parts to help you build the engine you've envisioned, from mild street builds to full-on race applications. Let's walk through the key upgrades that will take your FA20 to the next level.
Reliability First: The Air/Oil Separator (AOS)
Before you even think about adding more power, your first move should be to protect the engine you have. The FA20, like many direct-injection engines, is prone to oil consumption and carbon buildup on the intake valves. This happens when oil vapor from the crankcase is recirculated back into your intake, where it can lower your fuel's octane rating and bake onto the valves, restricting airflow. Installing a high-quality Air/Oil Separator (AOS) is one of the most effective preventative performance parts you can add. An AOS intercepts these oil vapors, separating the oil and returning it to the engine, while allowing clean air to pass through. This simple upgrade keeps your intake clean, maintains performance, and is a foundational step for long-term engine health.
Start Here: Strengthening the Internals
Before you chase high horsepower figures, you have to build a strong foundation. The FA20’s stock pistons and connecting rods are the primary weak points when you start adding significant power. To create a reliable high-power engine, replacing these with forged versions is non-negotiable. There’s a myth that built FA20s are fragile, but that’s only true if they’re built or maintained improperly. When you start with high-quality forged internals, you create an engine that can safely handle the increased stress and power you plan to throw at it. This is the essential first step for any serious performance build, ensuring your engine can withstand the demands of increased cylinder pressure and higher RPMs without compromise.
High-Strength Head and Main Studs
Once you've upgraded the pistons and rods, the next step is to secure the entire assembly. The factory head bolts and main bolts are designed for stock power levels, but they can stretch under the higher cylinder pressures of a modified engine. This stretching can lead to catastrophic failures, like a blown head gasket or shifting main bearings. To prevent this, you need to use stronger head and main studs to reinforce the engine block. High-strength studs provide significantly more clamping force, ensuring the cylinder heads stay sealed and the crankshaft stays perfectly aligned, even under extreme boost. This is a foundational part of any serious build and a critical step in creating a durable engine that can handle real power with reliable performance parts.
Upgrading the Valvetrain
A strong short block is only half the equation; your engine also needs to breathe efficiently at high RPMs. The valvetrain controls the flow of air and fuel, and the stock components can become a limitation. At high engine speeds, factory valve springs can struggle to close the valves quickly enough, a condition known as valve float. This can cause a loss of power and, in severe cases, lead to the piston making contact with a valve. Upgrading to stiffer valve springs, lightweight retainers, and performance valves prevents this issue, allowing your engine to rev higher and safer. This is essential for anyone planning to run aggressive cams or push the rev limiter, ensuring your FA20 can make power reliably throughout the entire RPM range.
Advanced Block Modifications: Closed-Decking and Stroking
For those chasing the highest horsepower figures, you may need to go a step further and strengthen the engine block itself. The FA20 features an open-deck design, which is great for cooling but leaves the cylinder walls unsupported at the top. Under very high boost, these walls can flex or even crack. The solution is "closed-decking," a process where a reinforcing plate is inserted into the block to support the cylinders. This modification is critical for anyone aiming for 500+ horsepower. For even more performance, some builders opt for stroking the engine—using a different crankshaft to increase displacement for more torque. These advanced modifications require precision machine work and are a key part of professional engine tuning services that separate a standard build from a truly robust race motor.
More Power: Turbo and Fuel System Upgrades
Once your engine’s internals are fortified, you can focus on making more power. This means getting more air and fuel into the cylinders. The stock fuel system can become a bottleneck, especially if you’re aiming for more than 450 horsepower. To overcome this, you’ll likely need a secondary fuel system, like port injection, to deliver the necessary volume. Of course, you’ll also need a larger turbo to supply the extra air. To manage the increased stress, you may also need to reinforce the block and upgrade the cylinder heads for better airflow. These modifications require professional engine tuning services to ensure everything works in harmony and your air-fuel ratios are dialed in perfectly for safe, reliable power.
Turbocharger vs. Supercharger
Forced induction is the key to unlocking serious power from your built FA20, and you have two main paths: turbocharging or supercharging. Turbochargers use exhaust gases to spin a turbine, forcing more air into the engine. They are known for producing significant power gains, especially in the mid-to-high RPM range, making them a favorite for enthusiasts aiming to maximize horsepower for track days. On the other hand, superchargers are driven directly by the engine's crankshaft, providing instant power across all engine speeds. This linear delivery is great for daily driving and street applications where smooth, immediate throttle response is preferred. The choice between them really comes down to your driving style and what you want to feel when you press the accelerator.
Upgrading the Fuel System for E85 and High Power
Adding a bigger turbo or a supercharger is only half the equation. To make more power safely, you need to supply more fuel. When aiming for more than 450 horsepower, upgrading the fuel system becomes essential, often requiring a secondary port injection system to ensure adequate fuel delivery. This is especially true if you plan to run E85 fuel, which requires approximately 30% more volume than regular gasoline. To meet this demand, you'll need larger fuel injectors and a high-flow fuel pump. This isn't an area to cut corners; a robust fuel system is critical for preventing lean conditions that can lead to catastrophic engine failure. Proper engine tuning services are required to recalibrate the system for these new components.
Keeping it Cool: Radiators, Oil Coolers, and Support Mods
More power generates more heat—it’s a simple fact. The factory cooling system is designed for stock output and can quickly become overwhelmed in a performance application. To protect your investment and maintain consistent power, upgrading your cooling system is critical. Installing a larger radiator and a dedicated engine oil cooler will help manage temperatures and prevent overheating during aggressive driving or track days. These supporting systems are just as important as the power-adding parts. They ensure your engine runs reliably, especially for demanding applications like our overlanding solutions, where dependability is everything. Don't let excessive heat rob you of performance or, worse, damage your newly built engine.
Improving the Oiling System
Your engine's oiling system is its lifeblood, especially when you're pushing for more power. During aggressive cornering on a track or canyon road, the high G-forces can cause the stock system to struggle, leaving the oil pickup unsubmerged. This leads to oil starvation, a quick way to cause catastrophic engine failure. Before you add any significant power, you must address this weak spot. Installing a baffled oil pan and an upgraded oil pickup tube are essential first steps for a consistent oil supply. Additionally, one of the best preventative performance parts you can install is a quality Air/Oil Separator (AOS). It keeps oil vapor out of your intake, which reduces carbon buildup and helps your engine run cleanly—a critical factor for the health of any built motor.
Installing Your New FA20 Engine
Once you have your new FA20 engine, the next critical phase is installation. This step is just as important as selecting the right build, as a poor installation can undermine even the highest quality engine. Proper installation ensures your investment performs as expected and remains reliable for years to come. It’s about more than just swapping parts; it’s about integrating the new heart of your Subaru correctly so it can handle the power you plan to unleash.
Breaking Down Installation Labor and Costs
The cost of installing an FA20 engine can vary significantly based on the complexity of your build and the shop you choose. A straightforward swap of a stock engine will be on the lower end of the spectrum, typically involving a set number of labor hours. However, if you’re installing a high-performance built motor, the process becomes much more involved.
A properly built FA20 short block can handle over 600 HP, but achieving that requires more than just dropping the engine in. The installation will involve fitting upgraded components, potentially custom fabricating parts, and ensuring every system works in harmony. This additional complexity increases labor time and, consequently, the cost. When getting quotes, be sure to find a reputable shop with proven experience in Subaru performance builds. Their expertise is worth the investment.
Don't Forget Supporting Parts and a Pro Tune
A high-performance engine is only as strong as its weakest link. Upgrading supporting systems like cooling, fuel, and oil management is just as important as upgrading the engine's internal parts. Your stock components were designed for stock power levels and will quickly become overwhelmed by the demands of a built motor. Before installation, you need to plan your build based on how much power you want and how you'll use the car.
Key upgrades to consider include a higher-flow fuel pump and injectors, an upgraded radiator, and a robust oil cooling system. An Air/Oil Separator is also a non-negotiable addition to protect your engine from oil blow-by. You may also need to strengthen your drivetrain with a new clutch and flywheel to handle the increased torque. Once all the hardware is installed, professional engine tuning services are essential. A tuner will recalibrate your ECU to optimize performance and ensure the engine runs safely with its new set of performance parts.
The Role of Safety Limits in a Professional Tune
A great tune does more than just make your car fast; it makes it smart. Think of a professional tune as a set of instructions that includes critical safety limits to protect your engine. These aren't just about capping your redline. A skilled tuner programs failsafes into the engine's computer that monitor crucial parameters like boost pressure, air-fuel ratios, and temperatures. If a sensor detects a dangerous condition—like a fuel pump failing and causing the engine to run lean—the tune will automatically intervene by cutting boost or reducing power to prevent catastrophic damage. This is the single biggest difference between a cheap "glory tune" and professional engine tuning services. You're not just paying for horsepower; you're investing in a sophisticated safety net that protects your newly built motor when something unexpected goes wrong.
Should You DIY or Hire a Pro for Installation?
While a DIY engine installation can be a rewarding project for an experienced mechanic with the right tools, it’s a massive undertaking. For most owners, especially those investing in a high-performance built engine, professional installation is the recommended path. Building an engine isn't just about getting a high horsepower number; it's about making the engine strong enough to handle that power reliably.
Professional installers have the specialized tools and experience to handle the unique challenges of the FA20 platform. They can troubleshoot unexpected issues, ensure every bolt is torqued to spec, and provide guidance on the critical engine break-in process. A common misconception is that a built motor doesn't require careful maintenance, but the opposite is true. A professional shop will set you up for success with a solid installation and clear instructions for long-term care, often backed by a labor warranty for added peace of mind.
Maintaining and Monitoring Your Built FA20
Your new engine is in, and the break-in period is complete. Now, the real work of ownership begins. A high-performance built engine is not a "set it and forget it" upgrade; it's a precision machine that requires diligent care to deliver the reliable power you invested in. Think of it like a high-performance athlete—it needs a specific regimen to stay in peak condition. Consistent maintenance and active monitoring are the keys to longevity. By staying engaged with your vehicle's health, you can catch small issues before they become catastrophic failures, ensuring you can enjoy every bit of performance your FA20 has to offer for years to come.
Essential Maintenance Schedule
A built FA20 operates under far greater stress than a stock motor, which means its maintenance needs are more demanding. The factory service schedule is a good starting point, but it’s not enough to protect your investment. You’ll need a more frequent and thorough maintenance plan to account for the increased heat, pressure, and power your engine is producing. Sticking to a strict schedule for fluid changes and preventative services is the most effective way to ensure your engine remains healthy, whether you’re on the street, track, or trail. This proactive approach is your first line of defense against premature wear and tear.
Oil Change Intervals for Built Engines
For a built engine, frequent oil changes are non-negotiable. The intense heat and higher cylinder pressures of a performance build cause engine oil to break down much faster than in a stock application. We recommend changing your oil and filter every 3,000 to 6,000 miles, using only high-quality full synthetic oil. This simple, consistent service is the single most important thing you can do to protect your engine's forged internals. Clean oil properly lubricates, cools, and cleans critical components, preventing premature wear on bearings and pistons. Think of it as the cheapest insurance policy you can buy for your high-performance investment.
Intake Valve Carbon Cleaning
The FA20’s direct injection system is great for efficiency, but it has a downside: carbon buildup on the intake valves. Because fuel is injected directly into the cylinder, it never washes over the valves to clean them. Over time, oil vapor from the crankcase ventilation system bakes onto the hot valves, forming hard carbon deposits that restrict airflow and can rob your engine of power. To keep your engine breathing freely, you should schedule a professional carbon cleaning service, like walnut blasting, every 40,000 to 60,000 miles. Installing quality performance parts like an Air/Oil Separator can also significantly reduce the rate of buildup.
Real-Time Engine Monitoring
Beyond scheduled maintenance, becoming an observant and engaged driver is crucial for the health of your built FA20. This means paying close attention to how your car sounds, feels, and performs on a daily basis. It also means using modern tools to keep an eye on the engine's vital signs in real time. A built motor often provides fewer warning signs before a major issue occurs, so active monitoring allows you to spot subtle changes in performance or engine parameters. This vigilance can be the difference between a minor adjustment and a complete engine rebuild, giving you the power to protect your investment.
Installing Gauges to Track Engine Health
Gauges and monitoring devices are not just for looks; they are essential diagnostic tools for any performance vehicle. A device like a Cobb Accessport or a set of dedicated gauges for oil pressure, oil temperature, and air-fuel ratio (AFR) provides a constant stream of data on your engine's health. These tools allow you to see if your engine is operating within the safe parameters established by your professional tune. If you notice your oil pressure dropping or temperatures climbing higher than normal, you can shut the car down and investigate before serious damage occurs. This data is invaluable for anyone who relies on professional engine tuning services to push their vehicle's limits safely.
Checking Oil Levels Frequently
It is perfectly normal for a high-performance engine to consume a small amount of oil between changes. The higher operating temperatures and pressures can cause some oil to get past the piston rings and burn off in the combustion chamber. Because of this, you can't afford to wait until your next scheduled oil change to check the level. Get into the habit of checking your dipstick every other time you fill up with gas. This simple, two-minute routine is one of the easiest and most effective ways to prevent catastrophic engine failure due to oil starvation. Keeping the oil topped off ensures your engine always has the lubrication it needs to perform reliably under pressure.
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Frequently Asked Questions
Is a built FA20 engine reliable enough for a daily driver? Absolutely. There's a common myth that a built engine is only for the racetrack, but that isn't the case. Reliability comes down to the quality of the build, the tune, and the maintenance. A professionally assembled engine using high-quality forged internals is significantly stronger than a stock one. When paired with a conservative, professional tune and diligent maintenance, a built FA20 can be a perfectly dependable engine for your daily commute while still having plenty of power on tap for the weekend.
What's the difference between a short block and a long block? This is a great question that often causes confusion. Think of a short block as the bottom half of the engine; it typically includes the engine block itself, crankshaft, connecting rods, and pistons. A long block includes the entire short block plus the top half of the engine, which means the cylinder heads, camshafts, and valvetrain are already assembled and attached. Knowing the difference is key when you're shopping, as it determines how many of your old engine's parts you'll need to transfer over.
Why is an Air/Oil Separator (AOS) so critical for the FA20? The FA20 is a direct-injection engine, which means fuel is sprayed directly into the cylinder instead of washing over the intake valves. Because of this, oil vapor from the crankcase can get recirculated into the intake and bake onto the valves, causing carbon buildup that hurts performance. An Air/Oil Separator intercepts this vapor, separating the oil and returning it to the engine, which keeps your intake valves clean and reduces overall oil consumption. It's one of the most important supporting mods you can make for engine health.
Can I put the turbocharged FA20F from a WRX into my BRZ? While it might sound like a straightforward swap since they share the "FA20" name, it's a very complex and expensive project. The WRX and BRZ engines have different fuel systems, wiring harnesses, and engine computers (ECUs). Making them work together requires extensive custom fabrication and electronic work. For most owners, it's far more practical and cost-effective to add a turbo or supercharger kit to the existing BRZ engine, especially if you've already strengthened it with a built short block.
How important is the engine break-in process? The break-in period is the most critical time in your new engine's life. This process allows the new piston rings to properly seat against the cylinder walls, which is essential for creating strong compression and ensuring the engine's long-term health and performance. Skipping or rushing this step can lead to excessive oil consumption and reduced power down the road. Always follow the specific break-in instructions provided by your engine builder, as they will have a precise procedure of varying engine loads and oil changes to ensure everything settles in perfectly.