How to Pick a Performance Cylinder Head for Your Subaru
Hitting a wall with your build? You've upgraded the turbo and dialed in the tune, but the power just isn't there. The culprit is often hiding right on top of your engine. Stock cylinder heads are designed for your daily commute, not for making serious power. They're the ultimate bottleneck, choking your engine and limiting every other mod you've made. Think of it like trying to run a marathon while breathing through a coffee stirrer. A performance cylinder head upgrade is the only way to let your engine truly breathe. It's the foundational change that unlocks the full potential of your entire setup.
Key Takeaways
- Performance Heads Are the Foundation for Power: Upgrading your cylinder heads improves your engine's airflow, which is essential for making more power. This modification allows your entire system, from the intake to the turbo, to work together efficiently and support higher horsepower reliably.
- Match the Head to Your Specific Build: The right cylinder head must be compatible with your Subaru's model and year (2002-present). More importantly, it should align with your performance goals, as a head designed for a high-revving track car is fundamentally different from one for a daily driver.
- A Tune is Non-Negotiable: Performance cylinder heads are not a standalone upgrade. To safely achieve power gains, they must be integrated with compatible components and supported by a professional engine tune that adjusts fuel and timing to match the improved airflow.
What Makes a Cylinder Head a "Performance" Upgrade?
Think of your engine as a set of lungs. The cylinder heads are the critical passages that control how well it breathes. Performance Subaru cylinder heads are aftermarket components engineered to improve this breathing process, allowing your engine to take in more air and fuel and expel exhaust gases more efficiently. Unlike stock heads, which are designed for a balance of economy and daily driving, performance heads are built for strength, durability, and maximum power output. They are a foundational part of any serious engine build, especially for Subaru models from 2002 to the present that are destined for the track, trail, or spirited street driving.
These specialized heads are crafted from high-quality materials and feature precision-machined surfaces to handle the increased stress from higher horsepower and torque. Whether you're modifying a WRX, STI, or Crosstrek, upgrading your cylinder heads is a significant step toward building a more powerful and reliable engine. It’s about moving beyond factory limitations and creating a setup that can support your other performance parts and deliver the results you’re looking for.
Performance vs. Stock: What's the Difference?
The main difference between performance and stock cylinder heads comes down to design and airflow dynamics. Stock heads are mass-produced with compromises for cost and emissions, while performance heads are optimized for one thing: power. For example, the FA20 cylinder head in a BRZ is designed differently from its WRX counterpart, with unique ports optimized for higher RPMs. Performance versions take this a step further, refining port shapes and sizes to smooth out airflow and eliminate restrictions.
Beyond porting, performance heads often feature upgraded valve train components, like stronger springs and larger valves, to handle more aggressive camshafts and higher engine speeds. Details like port alignment and valve seating are also meticulously addressed. A poorly aligned port can disrupt airflow and hurt performance, while a perfect valve seat ensures maximum compression. These small but crucial details are what separate a high-flow performance head from a standard factory part.
Why an Upgrade Is Worth It
Upgrading to performance cylinder heads unlocks significant gains in engine efficiency and power. The primary benefit is dramatically improved airflow. By allowing your engine to breathe more freely, you enable it to burn more fuel, which directly translates to more horsepower and torque. Many performance heads feature advanced port designs that help evacuate exhaust gases more effectively, creating a smoother and more powerful combustion cycle.
This upgrade also improves engine durability. The robust construction and superior materials used in performance heads can better withstand the high temperatures and pressures of a modified engine. Modifications like a 5-angle valve job further refine the airflow path around the valves, creating a more efficient seal and better flow characteristics. Ultimately, better heads allow your entire engine package—from the intake to the exhaust—to work together more effectively, creating a more responsive and powerful driving experience.
Beyond Subaru: A Look at the Broader Market
While our expertise is rooted in the Subaru boxer engine, the fundamental principles of a performance cylinder head upgrade apply across the entire automotive world. The goal is always to improve how an engine breathes, and stock heads are almost always a point of restriction, regardless of the make or model. Performance heads are engineered to optimize airflow dynamics, whether for a high-revving Honda or a big-torque American V8. The use of superior materials for durability and upgraded valve train components to handle higher stress are universal needs in any serious build. This focus on maximizing efficiency and strength is why a cylinder head upgrade is considered a foundational step for enthusiasts building any type of performance vehicle, not just a Subaru.
Understanding Cylinder Head Categories and Tiers
Once you decide to upgrade, you'll find that performance cylinder heads aren't a one-size-fits-all solution. They are categorized based on their intended application, level of modification, and whether they are built from a new or existing core. Understanding these differences is key to selecting the right foundation for your engine build. Choosing the wrong type can mean leaving power on the table or creating a car that’s difficult to drive on the street. Let's break down the main categories you'll encounter so you can make an informed decision that aligns perfectly with your goals for your Subaru.
Street vs. Competition Heads
The most fundamental distinction is between heads designed for the street and those built for competition. Street performance heads aim for a balance between increased power, reliability, and everyday drivability. They improve airflow significantly over stock but are engineered to maintain good low-end torque and a smooth powerband, making them ideal for a daily driven WRX or a modified Forester. They are built with durability in mind to handle spirited driving without requiring the constant maintenance of a full-blown race engine. These heads are the perfect match for bolt-on modifications and a solid tune.
Competition heads, on the other hand, are all about maximum power output. They feature aggressive porting, oversized valves, and heavy-duty valve train components designed to function at high RPMs. This focus on peak performance often comes at the expense of street manners, sometimes resulting in a rough idle or reduced low-end power. These are the heads you want for a dedicated track Subaru STI or a drag car where every last horsepower counts. They are engineered for the extreme stress of racing and are a must for any build pushing for serious numbers.
Staged Upgrades (Stage 1, 2, 3)
Many manufacturers simplify the selection process by offering cylinder heads in stages. While the specifics can vary, these stages generally represent an increasing level of performance and modification. A Stage 1 head is typically a great entry-level upgrade, often featuring a mild port and polish and upgraded valve springs. It’s designed to complement basic bolt-on parts and provide a noticeable improvement over stock. Stage 2 heads are a significant step up, with more extensive porting, larger valves, and components capable of supporting a bigger turbo and higher boost levels for a more serious build.
Stage 3 represents the most aggressive option, intended for high-horsepower race applications. These heads feature extensive, custom port work and a fully built valve train designed for maximum airflow at very high engine speeds. It’s crucial to match the stage of your cylinder heads to the rest of your performance parts. Installing Stage 3 heads on an otherwise stock engine won't yield the desired results; the entire system must be built to work in harmony to achieve its full potential.
Remanufactured vs. New Heads
When shopping for cylinder heads, you'll see both "new" and "remanufactured" options. New heads are created from brand-new, aftermarket castings, often designed from the ground up for performance. Remanufactured heads, however, start as used OEM cores. These cores are thoroughly cleaned, inspected for any defects, and then machined and rebuilt with high-performance components. A quality remanufacturing process isn't just about repair; it's a complete re-engineering of the original head to exceed factory specifications and fix common weak points.
Choosing a remanufactured performance head can be a cost-effective way to get a high-quality upgrade. Since they are based on the original factory design, fitment is guaranteed. More importantly, reputable builders use this process to address known issues, such as improving valve seats or strengthening the casting in critical areas. This results in a head that is often more durable and reliable than the original part it was based on, making it a smart choice for builders who need proven performance without starting from a completely custom casting.
Pro-Port Raw Heads for Custom Builds
For the most demanding applications, there are pro-port raw heads. These are essentially blank canvases for professional engine builders. They are new, unfinished castings sold without any port work or components installed. This allows a skilled builder to have complete control over every aspect of the head's design, from the shape and size of the intake and exhaust ports to the choice of valves, springs, and retainers. It’s the ultimate option for creating a truly bespoke setup tailored to a unique, high-end racing engine.
This category is not for the average enthusiast. It requires specialized knowledge, precision tools, and a deep understanding of engine airflow dynamics. Pro-port heads are typically reserved for professional race teams or custom engine shops building one-of-a-kind power plants for a specific purpose. For most Subaru owners, a pre-configured performance head for a Crosstrek or WRX will provide more than enough performance, but the existence of raw heads highlights the incredible depth and customization possible in the world of engine building.
Why Upgrade Your Subaru's Cylinder Heads?
Upgrading your Subaru's cylinder heads is one of the most effective ways to unlock significant gains in power, durability, and overall engine efficiency. Think of them as the lungs of your engine—improving them allows your entire system to perform at a higher level. While it's a more involved modification, the results are foundational for any serious build. Here’s why it’s a modification worth considering.
Gain More Horsepower and Torque
The primary reason to upgrade your cylinder heads is for more power. As one of the most important parts when it comes to making power in an engine, performance heads are designed to let your engine breathe more freely. Stock heads can be a bottleneck, but an upgrade opens the floodgates. Techniques like a 5-angle valve job reshape the valve seats to dramatically improve airflow. This allows a denser air-fuel mixture into the combustion chamber and helps exhaust escape faster, directly translating to significant gains in horsepower and torque across the entire RPM range. It's a foundational change that lets other mods, like a bigger turbo, truly shine.
Realistic Horsepower Gains
So, what kind of numbers can you actually expect? While it’s tempting to look for a specific figure, the horsepower gains from cylinder heads depend entirely on your overall build. For a relatively stock engine, simply porting the heads might yield a modest 10–20 horsepower. However, their true value is realized in a modified setup. Performance heads remove a critical bottleneck, allowing your turbo, cams, and intake to function at their full potential. On a built motor, the difference can be substantial, often unlocking 50 horsepower or more that was previously inaccessible. The key is to see them not as an isolated upgrade, but as the component that enables all your other parts to work together. To safely realize these gains, a professional tune is essential to recalibrate your engine’s parameters for the massive increase in airflow.
Build a More Durable, Cooler Engine
Pushing your Subaru generates more heat and stress, and your engine components need to be up to the task. Performance cylinder heads are constructed with higher-quality materials than stock, offering improved durability and heat resistance. This ensures your engine can withstand the rigors of high-performance driving, from track days to demanding trails. For turbocharged engines running increased boost, this added strength is essential for preventing component failure and ensuring long-term reliability. You gain peace of mind knowing your engine's top end is built to handle the extra power you're making.
Maximize Your Engine's Airflow
Better performance isn't just about cramming more air in; it's about creating an efficient cycle. Performance heads are engineered with optimized ports and valve designs to streamline airflow. This design allows for improved exhaust gas evacuation, which reduces backpressure and enhances overall engine efficiency. When you use a turbo or supercharger, this optimized airflow becomes even more critical for maximizing boost and power. A more efficient engine also runs cooler, as it doesn't have to work as hard to expel exhaust gases, helping you maintain stable performance under load.
Which Cylinder Head Brands Can You Trust?
When you start shopping for performance cylinder heads, you'll quickly notice a few key brands that dominate the conversation in the Subaru community. These companies have built their reputations on proven results, quality engineering, and a deep understanding of the EJ and FA engines that power our favorite cars. Choosing the right brand isn't just about picking the one with the biggest horsepower claims; it's about finding a partner whose philosophy aligns with your build goals. Some brands specialize in complete, ready-to-install packages designed for specific power targets, taking the guesswork out of the equation. Others are known for their high-flow valvetrain components that allow experienced engine builders to create a truly custom setup. Whether you're building a reliable daily driver with a bit more punch or a full-blown track monster, there's a brand that caters to your needs. It's important to understand what each one brings to the table so you can make an informed decision that supports your entire build, from the block to the turbo. Let's look at some of the top players to help you decide where to start your search.
Crawford Performance
With a deep history in Subaru racing, Crawford Performance brings track-proven engineering to every product. They are renowned for their specialized cylinder head packages tailored specifically for WRX, STI, and BRZ/FRS models. Instead of just selling parts, they offer complete, tiered solutions designed to improve power, efficiency, and engine longevity. This approach simplifies the upgrade process, ensuring all components work together seamlessly for reliable performance. Whether you're aiming for a modest power increase or a competitive race build, their packages are engineered to deliver consistent and dependable results, drawing from decades of experience tuning and building high-output Subaru engines.
IAG Performance
IAG Performance is another major player in the Subaru world, offering a wide array of cylinder heads and engine components. Their products are engineered with a heavy focus on durability, making them a go-to choice for modified engines pushing for higher power levels. IAG is known for creating parts that reinforce engine strength and longevity, catering to both aggressive street builds and dedicated race applications. If you're planning a high-boost setup or need components that can withstand serious abuse on the track, IAG’s reputation for robust engineering makes them a brand worth considering for your build.
Brian Crower
Brian Crower is a well-respected name across the entire performance automotive industry, not just within the Subaru scene. They are known for high-performance engine internals, including camshafts, valvetrains, and cylinder heads designed to maximize airflow and engine efficiency. Their components are often the choice for builders aiming for significant horsepower gains, as their designs are focused on optimizing every aspect of the engine's breathing capabilities. If your build plan involves a custom setup where you're hand-picking each component for ultimate performance, Brian Crower offers the high-quality parts needed to achieve your goals.
GSC Power Division
GSC Power Division specializes in high-performance valvetrain components, and their expertise shines through in their cylinder head offerings. Their products are meticulously engineered for optimal airflow and are designed to support high-horsepower builds. Within the Subaru performance community, GSC has earned a strong reputation for quality, precision, and reliability. They are a popular choice for enthusiasts who want to ensure their engine can handle the demands of increased power without sacrificing stability. If you prioritize a well-designed valvetrain that can keep up with an aggressive turbo and fuel setup, GSC is a brand to keep on your shortlist.
How to Read a Cylinder Head Spec Sheet
When you start comparing performance cylinder heads, you'll run into a lot of technical jargon. Don't let it intimidate you. Understanding a few key specifications will help you cut through the noise and identify what truly matters for your build. The right head isn't just about a brand name; it's about matching the engineering to your performance goals. Focusing on port design, material quality, valve configuration, and compression ratio will ensure you choose a head that works with your engine, not against it, to create reliable power.
Understanding Port Design and Airflow
Think of the ports in your cylinder head as the engine's respiratory system. Their design dictates how efficiently air and fuel get into the combustion chamber and how quickly exhaust gets out. A well-designed port creates a smooth, fast-moving column of air, which is essential for maximizing engine efficiency and power. For example, some heads are engineered with smaller ports to keep air velocity high, which is great for naturally aspirated engines that need to perform well at higher RPMs. For turbocharged applications like a WRX or STI, you might look for larger, reshaped ports that can handle the massive volume of air being forced into the engine.
Exhaust Port Shape and Valve Angle
The geometry of the exhaust port and the angle of the valves are where the real engineering magic happens in a performance head. It’s not about simply hogging out the ports to make them bigger; it’s about shaping them for optimal flow. A well-designed exhaust port provides a smooth, unobstructed path for spent gases to exit, which lowers backpressure and lets the engine cycle more efficiently. This is where the valve angle plays a key role. Techniques like a multi-angle valve job are used to reshape the valve seat with a series of precise cuts. This creates a gentler transition for exhaust gases to flow around the valve, improving efficiency throughout the entire lift range. The result is a more responsive engine that makes more power because it isn't wasting energy fighting to exhale. These meticulous details are what truly distinguish a high-performance head from a stock one.
Why Material and Build Quality Matter
Performance engines generate a lot more heat and pressure than stock ones, and the cylinder head bears the brunt of it. This is why material and construction quality are non-negotiable. Most performance heads are made from high-grade aluminum alloys, but the quality comes from the casting and machining processes. Look for heads made from durable, heat-treated materials that resist warping or cracking under stress. A well-built head provides the foundation for a reliable engine, giving you confidence whether you're on the track or a daily commute. Investing in quality materials is one of the best ways to protect your entire engine build.
Common Materials: A356 Aluminum and Cast Iron
When you examine the specs, you'll find that most modern performance cylinder heads are crafted from A356 aluminum. This specific alloy is the go-to choice for a reason: it offers an excellent combination of strength and light weight, and it's fantastic at dissipating heat—a critical feature for turbocharged Subaru engines. This is a significant improvement over older, heavier cast iron heads, which retain more heat and add unnecessary weight to the top of the engine. Top-tier manufacturers across the industry rely on A356 aluminum because it provides the durability required to handle the increased cylinder pressures and temperatures of a high-performance build, ensuring the head won't fail when you need it most.
Look for Quality Assurance Markers
The raw material is only half the story; the manufacturing process is what turns a good casting into a great cylinder head. Look for brands that are transparent about their quality control. Certifications like ISO 9001 are a strong indicator that a company adheres to strict, repeatable manufacturing standards. This commitment to quality ensures that every port is precisely machined, every valve seat is perfectly cut, and every surface is flawlessly finished. This attention to detail translates directly to easier installation, reliable performance, and the peace of mind that comes from knowing your investment is built to last under the stresses of high-performance driving.
Choosing Your Valve Setup
The valves are the gatekeepers of your engine's combustion chamber. While the number of valves is important, the real performance gains come from the "valve job," which refers to how the valve seats are machined. A performance-oriented 5-angle valve job is a modification that reshapes the seats to create a smoother path for air to flow around the valve. This simple change can significantly reduce turbulence and improve airflow, leading to more efficient combustion and a noticeable increase in power. It’s a detail that makes a huge difference in how well your engine breathes.
Specialized Valves and Rocker Arm Ratios
Beyond the precision of the valve job, the valves themselves and the components that control them are critical. Performance heads often incorporate larger valves to increase the flow area, along with stronger valve springs and lightweight retainers. These upgrades are essential for preventing "valve float" at high RPMs, a condition where the springs can't close the valve fast enough to keep up with the piston. This robust valvetrain is what allows you to run more aggressive camshafts, which dictate how far the valves open and how long they stay open. It's this synergy between all the valvetrain components that truly defines a performance head, ensuring everything works in harmony to support higher engine speeds and greater power output reliably.
How Compression Ratio Affects Performance
The compression ratio is a measure of how much the air-fuel mixture is squeezed before ignition. The shape and volume of the combustion chamber in the cylinder head are major factors in determining this ratio. Generally, a higher compression ratio leads to more power, as it creates a more potent explosion. However, it's a delicate balancing act. The ideal ratio depends heavily on your fuel type and whether you're running a naturally aspirated or forced induction setup. High compression requires high-octane fuel and precise engine tuning services to prevent engine knock, which can be destructive.
The Role of Combustion Chamber Volume
The volume of the combustion chamber—the small space at the top of the cylinder where the magic happens—is a critical piece of the compression puzzle. This measurement directly influences your engine's compression ratio. A smaller chamber volume squeezes the air-fuel mixture more tightly, resulting in a higher compression ratio, which can lead to more power. Conversely, a larger chamber volume lowers the compression ratio. The choice depends entirely on your build. A high-revving, naturally aspirated engine might benefit from a smaller chamber, while a high-boost turbocharged STI might require a slightly larger one to prevent detonation on pump gas. The ultimate goal is to achieve optimal combustion efficiency, ensuring the fuel burns completely and powerfully every time the spark plug fires.
How to Choose the Right Performance Cylinder Head
Selecting the right performance cylinder head is one of the most critical decisions you'll make for your engine build. It’s not just about bolting on a new part; it’s about finding the perfect match for your vehicle, your driving style, and your existing components. A well-chosen cylinder head works in harmony with the rest of your engine to deliver reliable power, while the wrong one can create bottlenecks or compatibility headaches. To make the best choice, you need to consider three key factors: vehicle-specific fitment, your ultimate performance goals, and how the new heads will integrate with your current setup. Getting this right means you'll have a responsive, powerful engine that feels perfectly suited to your needs, whether you're on the track, the trail, or the street.
Find the Right Fit for Your Model and Year
First and foremost, the cylinder head must be compatible with your Subaru’s specific model and year. The architecture of Subaru engines has evolved significantly since 2002, and a head designed for an early EJ engine will not fit a modern FA engine. Reputable manufacturers engineer their heads for precise fitment on specific vehicles, from the Subaru WRX and STI to the Crosstrek and Forester. Always verify that the part you’re considering is explicitly listed for your car’s production year. This ensures that bolt patterns, port shapes, and coolant passages line up perfectly, preventing installation issues and ensuring proper function from the start.
Define Your Performance Goals First
What do you want your Subaru to do? The answer will guide you to the right cylinder head. Are you building a high-revving track car that needs maximum airflow at the top of the powerband, or are you creating a responsive daily driver that requires strong mid-range torque? Crawford Performance offers specialized cylinder head packages designed for different outcomes, whether it's for street, race, or rally applications. A head with large, aggressive ports might be perfect for a 600-horsepower drag build but could feel sluggish on the street. Be honest about your goals to choose a head that enhances your driving experience, rather than compromising it.
Matching Heads to Your Engine's RPM Range
The powerband of your engine—the RPM range where it makes the most power—is heavily influenced by your cylinder heads. A head designed for a race car that lives above 6,000 RPM will have large ports to move massive amounts of air, but this can sacrifice low-end torque, making the car feel unresponsive in city traffic. Conversely, a head optimized for a daily driver or an overlanding build will focus on maintaining high air velocity at lower RPMs for better throttle response and mid-range pull. Performance heads use optimized ports and valve designs to streamline airflow, which is especially critical for turbocharged engines to make efficient power. The key is to match the head's design to where you spend most of your time driving, ensuring the power is available right when you need it.
Emissions Legality for Street Use
Before you finalize your choice, it's essential to consider emissions compliance, especially if your Subaru is a daily driver. Many high-performance parts are designated for "off-road use only," meaning they may not meet the legal standards for street driving in your area. However, some manufacturers design their performance parts to be legal in all 50 states. It's your responsibility to check local regulations and the manufacturer's specifications. A head designed for a dedicated track car won't have the same emissions considerations as one for a street-driven WRX. Choosing a compliant head ensures you can enjoy your car's new power without worrying about passing your next inspection.
Check Compatibility with Your Current Build
A cylinder head is a team player; it has to work seamlessly with your other engine components. The ports on the head must align properly with your intake and exhaust manifolds to avoid creating turbulence that hurts airflow. More importantly, the heads must be compatible with your camshafts, valves, and pistons. A high-lift cam, for example, requires a head with adequate valve-to-piston clearance. Mismatched components can lead to poor performance or catastrophic engine failure. This is why professional engine tuning services are essential after an installation to ensure every part works together harmoniously to produce reliable power.
The "Ready to Run" Advantage
Upgrading to performance cylinder heads is about unlocking your engine's true potential by fixing its most significant restriction: airflow. Stock heads are designed for a mix of economy and daily driving, but performance heads are engineered for maximum power output and durability. By allowing your engine to breathe more freely, they enable it to process more air and fuel, which directly translates to more horsepower and torque. This isn't just a minor tweak; it's a foundational change that allows all your other performance parts—from the intake to the turbo—to work together more effectively, creating a more responsive and powerful driving experience.
Upgrading Supporting Components
Performance cylinder heads are not a standalone upgrade. To see real gains and maintain reliability, they must be supported by compatible components and a professional tune. Performance heads often feature an upgraded valvetrain to handle more aggressive camshafts and higher engine speeds. More importantly, a tune is non-negotiable. The improved airflow completely changes your engine's dynamics, and the ECU must be recalibrated to adjust fuel and timing accordingly. Without proper engine tuning services, you risk poor performance or even severe engine damage. A holistic approach ensures every component works in harmony to safely deliver the power you're looking for.
Cylinder Head Upgrade Myths, Busted
When you're planning a build, bad advice can lead to costly mistakes. Cylinder head upgrades are a significant investment, and a lot of misinformation can send you down the wrong path. Let's clear up a few common myths so you can make an informed decision for your Subaru. Understanding these points will help you avoid common pitfalls and ensure your engine build is both powerful and reliable.
Are All Subaru Heads Interchangeable?
It would be convenient if you could swap any Subaru head onto your engine, but that’s a fast track to performance problems. Heads are designed for specific engine blocks, and details like port alignment and combustion chamber shape vary significantly between models. For example, an EJ series head from an STI won't work on an FA series engine in a newer WRX. Using the wrong head can cause poor airflow, sealing issues, and even engine damage. Always confirm that the heads you’re considering are made for your vehicle’s year and model to ensure a proper fit and optimal function for your Subaru WRX upgrades.
Do Performance Heads Add Instant Power?
Slapping on performance cylinder heads and expecting a massive power gain is a common misconception. While high-quality heads are essential for making big power, they are just one part of a system. The real improvement comes when the heads work with other components like your camshafts, turbo, and exhaust. The biggest factor? The tune. Without professional engine tuning services, your engine can't take advantage of the improved airflow. Think of performance heads as a critical component for reaching higher power levels—they don't create power on their own, but they allow the rest of your build to perform at its peak.
Is Machining Stock Heads a Good Idea?
While machining can be necessary for resurfacing a warped head, it’s not always the best route for a performance build. Every head has a specific grinding limit set by Subaru, and machining beyond that can create serious piston-to-valve clearance issues. Aggressively porting or decking stock heads can also introduce weak points, especially under the high stress of a modified engine. For serious performance goals, investing in purpose-built performance parts designed to handle increased power and heat is often a more reliable solution. It ensures you get the airflow you need without risking your engine's health.
Best Cylinder Heads for Your Subaru Model
Not all Subarus are created equal, and neither are their cylinder heads. The right performance head for a turbocharged STI built for the track will be completely different from what an overlanding Crosstrek needs. Understanding the specific architecture and performance characteristics of your model’s engine is the first step in making a smart upgrade. Let’s break down what you should look for based on your specific Subaru.
For Your WRX and STI
For owners of the iconic WRX and STI, the cylinder head is a gateway to serious power. The factory EJ257 heads are known for being a bit restrictive, which can hold back your engine's true potential. Upgrading to a performance head with improved port flow can make a massive difference in power output and engine efficiency. Companies like Crawford Performance offer specialized STI upgrades that are engineered to handle higher boost levels and deliver consistent power. These heads are designed not just for peak horsepower, but also for the durability needed to handle aggressive driving, making them a critical component for any serious build.
For Your Impreza and Forester
The Impreza and Forester are versatile platforms, and their cylinder head needs can vary widely depending on your build. Whether you're aiming for a reliable daily driver with a bit more punch or a full-blown sleeper build, the right head is crucial. Many of these models use the EJ Series engine, and there are excellent performance parts available that are engineered for strength and longevity. When choosing an upgrade, focus on components that promise durability and consistent performance. This ensures your engine can handle the added stress from other modifications while giving you the reliable power you need for any adventure.
For Your BRZ and Crosstrek
The BRZ and Crosstrek run on the non-turbo FA20 engine, which requires a different approach to cylinder head upgrades. These heads are engineered for high-RPM, naturally aspirated performance, focusing on maintaining high flow velocities through smaller ports. This design is key to their responsive feel. When considering an upgrade, it's less about massive ports and more about optimizing airflow characteristics to match your goals. Whether you're adding forced induction or staying naturally aspirated, the head must complement your setup. For Crosstrek upgrades, especially for overlanding, durability and efficient cooling are just as important as airflow.
A Smart Way to Compare Cylinder Head Brands
Once you’ve narrowed down your list of potential brands, it’s time to get into the details. Comparing cylinder heads isn't just about picking the one with the biggest numbers; it's about finding the right fit for your engine, your driving style, and your long-term goals. A high-quality head is a significant investment in your Subaru's performance and reliability, so looking at the right metrics is key. A head with incredible flow data won't do you any good if it's incompatible with your turbo setup or if you can't find a tuner who can work with it. You’ll want to evaluate everything from airflow characteristics and material strength to how it will integrate with your existing setup. Let’s walk through the four main areas to focus on so you can make a confident and informed decision.
Look at the Flow Bench Data
Flow bench data tells you how efficiently air moves through the cylinder head's ports. Better airflow generally means more potential for power, but it’s not always about the highest possible flow number. The velocity of the air is just as important. For example, a naturally aspirated engine like the BRZ's FA20 benefits from smaller ports that keep air velocity high at higher RPMs. In contrast, a turbocharged WRX relies on boost pressure to force air in, so its head is designed differently. When looking at data, consider how the head performs across the entire RPM range, not just at its peak. This will help you match the head’s characteristics to your specific engine and performance goals.
Inspect the Material and Build Quality
Your engine generates a massive amount of heat and pressure, and the cylinder heads bear the brunt of it. That’s why material quality is non-negotiable. Performance heads are typically made from high-grade aluminum alloys that offer superior strength and heat dissipation compared to stock materials. Look for brands that are transparent about the materials they use and their manufacturing processes, such as casting and heat-treating. Investing in a head made from high-quality materials gives you confidence that your engine can handle aggressive driving and demanding conditions, whether you’re on the track or a remote trail. The right performance parts are built for durability.
Confirm Forced Induction Compatibility
If you’re running a turbo or supercharger—or plan to add one—you must choose a cylinder head designed for forced induction. Because a compressor is forcing air into the cylinders, the head’s port and valve sizes don’t need to be as large as they would on a naturally aspirated engine to achieve great flow. The design of a forced induction head focuses on managing boost pressure and optimizing the combustion process under load. Always verify that the head you’re considering is compatible with your Subaru WRX upgrades or other forced induction system to avoid performance bottlenecks and potential engine damage.
Plan for Installation and Tuning
A performance cylinder head isn't a simple bolt-on part. To get the full benefit of your upgrade, it needs to be installed correctly and paired with a professional tune. The new head will change your engine's airflow dynamics, which requires adjusting fuel and ignition timing to optimize performance and ensure safety. When choosing a brand, consider the availability of technical support and whether they provide guidance for installation. Factoring in the cost and time for professional engine tuning services is a critical step in planning your build for long-term power and reliability.
Where Should You Buy Performance Cylinder Heads?
Once you’ve narrowed down the specs for your build, the next step is finding a reliable source. The quality of your supplier is just as critical as the quality of the cylinder head itself. Investing in a high-performance component means you need a seller who stands behind their products with expertise and a solid reputation. Cutting corners here can lead to counterfeit parts, poor performance, and a voided warranty. To protect your investment and ensure your Subaru gets the upgrade it deserves, focus your search on reputable sources that understand Subaru engineering.
Why to Choose an Authorized Dealer
Your first and safest bet is to purchase from authorized dealers or directly from the manufacturer. This guarantees you’re getting a genuine component, not a knock-off. Shops that specialize in Subaru performance are your best resource because their business depends on their expertise and reputation. They can provide expert advice to ensure the heads you choose are the perfect match for your vehicle and performance goals. When you work with a trusted source, you’re not just buying a part; you’re gaining a partner for your build who can offer guidance and support.
Avoiding Counterfeit and Used Parts
The performance parts market is full of deals that seem too good to be true, and they usually are. While a cheap, used cylinder head might seem like a budget-friendly option, it often comes with hidden risks like hairline cracks, warped surfaces, or a history of overheating that you can't see. Counterfeit parts are an even bigger gamble, as they lack the engineering and material quality to handle the stress of a modified engine, leading to poor performance and potential failure. The safest way to protect your investment is to purchase genuine performance parts directly from a trusted manufacturer or an authorized dealer. This ensures you receive a component that is built to spec, backed by a warranty, and supported by expert knowledge.
Use Reviews and Spec Sheets to Decide
Before you commit, do your homework. Look for detailed reviews from other Subaru owners who have used the specific cylinder heads you’re considering. Forums, owner groups, and product pages are excellent places to find honest feedback on real-world performance. Pay close attention to the detailed specifications provided by the manufacturer. Reputable brands will offer comprehensive data on their cylinder head packages, allowing you to compare airflow numbers, materials, and valve train components. This information is essential for making an informed decision that aligns with your build.
Don't Overlook Warranty and Support
A solid warranty is a clear indicator of a manufacturer's confidence in their product. For a critical engine component like a cylinder head, you should look for a company that stands behind its craftsmanship. For example, we back our performance parts with a standard 12-month or 12,000-mile warranty, giving you peace of mind. Equally important is the availability of technical support. If you or your mechanic have questions during installation, having access to expert help is invaluable. A company that offers robust support and engine tuning services demonstrates a deeper commitment to their customers' success.
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Frequently Asked Questions
Do I need to upgrade my cylinder heads for a daily driver? Not necessarily, but it depends on your goals. If you're simply looking for a bit more responsiveness for your daily commute, other modifications might be a better starting point. However, if your daily driver is also your project car and you plan on adding a larger turbo or significantly increasing power, then upgrading the heads becomes a smart move. It provides a stronger foundation for reliability and ensures your engine can safely handle the extra stress from other performance parts.
What other upgrades should I plan for when installing new cylinder heads? New cylinder heads are a team player, and they need a good supporting cast to perform their best. At a minimum, you should plan for new head gaskets and head studs. To take full advantage of the improved airflow, you should also consider matching them with appropriate camshafts, an upgraded intake manifold, and a less restrictive exhaust system. Most importantly, a professional engine tune is absolutely essential to recalibrate your ECU and make all the new components work together safely and efficiently.
Is a professional tune really necessary after this upgrade? Yes, it is non-negotiable. Installing performance cylinder heads fundamentally changes how your engine breathes. Without a proper tune, your engine's air-fuel ratio and ignition timing will be incorrect for the new airflow characteristics. This can lead to poor performance, reduced engine life, or even catastrophic failure. A professional tune ensures your engine runs safely, makes reliable power, and capitalizes on the full potential of your investment.
Is it better to port my stock heads or buy new performance heads? While porting stock heads can improve airflow, it has its limits and risks. The factory castings were not designed for the stress of high-horsepower applications, and aggressive porting can sometimes create weak spots. Buying a set of purpose-built performance heads from a reputable brand gives you a component engineered from the ground up for strength, durability, and optimized airflow. For serious builds, a new performance head is almost always the more reliable and effective long-term solution.
How do I choose between a complete cylinder head package and buying individual parts? A complete package is an excellent choice if you want a proven, all-in-one solution where the components are already matched for a specific performance target. This approach removes the guesswork and ensures compatibility between the valves, springs, and retainers. Buying individual components offers more flexibility for a custom build, but it requires a deep understanding of how each part affects the others. For most enthusiasts, a pre-configured package from a trusted builder offers the best balance of performance and reliability.