When it comes to Subaru, the brand’s loyal following isn’t just built on quirky marketing and symmetrical all-wheel drive. It’s the engines—those boxer powerplants—that have earned a reputation for being either bulletproof or… well, head gasket grenades waiting to blow.
Subaru engines can be as rugged and rally-capable as they are temperamental and tear-inducing. Whether you’re wrenching under the hood, carving canyon roads, or battling a snowstorm, the engine is the make-or-break factor in any long-term Subaru relationship.
The truth is, not all Subaru engines are created equal. Some are iron-willed warriors that will take a beating, keep pulling, and practically dare you to push harder.
Others, unfortunately, were seemingly built with a stopwatch counting down to failure—prone to overheating, oil starvation, or catastrophic detonation at the mere thought of spirited driving.
Subaru Engines That Handle Abuse
In this breakdown, we’re diving into ten of Subaru’s most talked-about engines: five that can take punishment like a champ, and five that fold under pressure. No fluff, no fanboy bias—just real talk on what works, what doesn’t, and what you need to know before throwing boost or big miles at a Subaru motor.
1. EJ22 (1990–2001 2.2L SOHC)
Arguably Subaru’s most legendary engine when it comes to toughness, the EJ22 is a non-interference, iron-block beast found in the early Legacy and Impreza models.
Known for its low maintenance requirements, it doesn’t suffer from head gasket failures as frequently as its larger EJ25 cousin. It can survive poor maintenance, overheating episodes, and even light neglect all while delivering 250,000+ miles.
The 2.2-liter engine made its debut in 1990 as the powerplant for Subaru’s newly introduced model—the Legacy. Around the same time, the 1.8-liter EJ18 was introduced, further expanding the EJ engine family.
The first version of the 2.2-liter engine was the EJ22E. This engine powered all USDM naturally aspirated 2.2-liter models from 1990 to 1996. It’s a four-cylinder boxer gasoline engine, featuring an aluminum cylinder block with cast iron sleeves.
The EJ22E was equipped with SOHC aluminum heads and belt-driven camshafts. Early versions of the engine had a compression ratio of 9.5:1.
In 1997, Subaru implemented several updates to the engine. These included solid lifters—requiring valve clearance adjustments every 100,000 miles—a roller rocker cam follower system, a switch to a single-port exhaust, and a slightly increased compression ratio of 9.7:1.
The updates aimed to reduce internal friction, thereby improving both power output and fuel efficiency. The pistons were reshaped and coated with molybdenum, with each piston made approximately 100 grams lighter. Subaru also redesigned the intake manifold to increase both the mass and velocity of incoming airflow.

The year 1996 marked a transitional period. Many EJ22E engines from this time already included upgraded components from the EJ22EZ, such as solid lifters. Despite the overlapping features, both the EJ22E and EJ22EZ are categorized under Phase 1 of the EJ engine lineage.
The EJ222 and EJ223 engines were produced from 1999 to 2001. Major revisions came in 1999 when the 2.2-liter engine adopted a Phase 2 design and incorporated technology found in the EZ series.
The standout feature was a new SOHC cylinder head design, with intake valves set at a 23-degree angle off-center and exhaust valves at a 20-degree angle. Additionally, the camshaft was now bolted directly to the cylinder head via an integrated camshaft case.
Turning to the turbocharged variants of the EJ22, the EJ22T was the engine found in USDM Legacy Turbo models from 1991 to 1994. It delivered 165 horsepower and came with SOHC aluminum heads, a fully closed deck block, internal oil sprayers, and notably, no intercooler.
On the JDM side, the EJ22G was developed as a high-performance engine derived from the EJ20K STI platform. While it shared the DOHC cylinder heads and turbocharger with the EJ20K, it used a 2.2-liter block that omitted piston-cooling oil sprayers.
The EJ22G featured forged pistons and stock connecting rods, with a low compression ratio of 8.0:1. Output was rated at 280 horsepower at 6,000 rpm and 268 lb-ft of torque at 3,200 rpm. This engine powered the legendary Impreza STi 22B GC8 series.
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2. EJ257 (2004–Present WRX STI 2.5L Turbo)
While finicky when modified poorly, the EJ257 in its stock or professionally tuned form is surprisingly robust. Built with forged pistons and a semi-closed deck design, it handles high boost levels and aggressive driving.
Many rally teams and track enthusiasts rely on this engine when properly cooled and maintained, making it one of Subaru’s more abuse-tolerant turbo engines.
The Subaru EJ257 2.5-liter turbocharged engine has been produced since 2004 at the company’s manufacturing plant. It is best known for its use in a range of performance-focused Impreza models, most notably those bearing the WRX STI designation.
In addition to the Impreza, a less aggressively tuned version of this engine has also powered sportier trims of the Subaru Forester and Legacy.
The sport-tuned STI versions of the EJ257 maintain the same 2457 cc displacement and fuel injection system but deliver higher performance. Power output ranges from 280 to 310 horsepower, with torque figures between 390 and 410 Nm.
These variants retain the aluminum H4 block and aluminum 16-valve cylinder heads, with the same bore and stroke dimensions of 99.5 mm and 79 mm, respectively.

However, the compression ratio is slightly lower, ranging from 8.0 to 8.2:1. Like the stock version, the STI versions use a DOHC layout, lack hydraulic valve lifters, and rely on a belt-driven timing system with AVCS variable valve timing. They also come equipped with a turbocharger.
The oil capacity for STI variants is slightly higher at 4.3 liters, still using 5W-30 oil. These engines also run on medium or plus-grade fuel and are certified under EURO 3, 4, and 5 emissions standards. The expected average lifespan for STI-modified EJ257s is approximately 200,000 kilometers.
The dry weight of the EJ257 engine is 175 kilograms. The engine identification number is stamped at the junction between the engine block and the transmission housing.
Regarding compression ratio, the Subaru EJ257 engine operates at 8.2:1. This figure means that when the piston is at the bottom of its stroke—referred to as bottom dead center (BDC)—the volume of the cylinder is 8.2 times larger than when the piston is at the top of its stroke, or top dead center (TDC).
The compression ratio is a key parameter in both engine performance and efficiency. Generally, a higher ratio can lead to increased power and improved fuel economy. However, it can also elevate the risk of engine knock or detonation, especially if the engine runs on fuel with insufficient octane.
In the EJ257’s case, the relatively low compression ratio of 8.2:1 is a deliberate design choice to maintain stable and reliable operation under high-boost conditions. It reduces the chances of detonation or knock, helping ensure that the engine performs consistently and remains durable even under heavy loads and demanding driving conditions.
3. FA24 (2019–Present 2.4L Turbo)
The FA24 powers newer models like the Ascent, WRX (2022+), and Outback XT. With direct injection, a modern turbo system, and a robust block design, the FA24 corrects many issues found in earlier turbo engines.
It tolerates heavy loads, long highway trips, and high temperatures better than its predecessors. With proper oil change intervals and cooling, it can withstand spirited driving and towing.
The FA24F’s design is centered around an open-deck aluminum cylinder block with cast-in iron liners. Compared to the earlier 2.0-liter FA20 engine, the bore diameter was increased from 86 mm (3.39 in) to 94 mm (3.7 in), while the stroke remained unchanged.
Like its predecessor, the FA24F uses diagonally split connecting rods, the same style found in the FA20DIT. However, it features newly designed pistons with a larger diameter to match the increased bore size. The engine is topped with aluminum dual overhead camshaft (DOHC) cylinder heads and a dual AVCS (Active Valve Control System).

Camshafts are driven by single roller timing chains—one on each side—rather than a timing belt. The valvetrain includes roller rocker arms but does not utilize hydraulic lash adjusters. Notably, the valve covers are made from plastic.
In contrast to the naturally aspirated FA20 and FA24D engines, which employ Toyota’s D-4S system (a combination of direct and port fuel injection), the FA24F uses only direct fuel injection. This means that fuel is injected solely into the combustion chambers.
A high-pressure fuel pump is mounted to the left-side cylinder head and is mechanically driven by the intake camshaft. In terms of forced induction, the FA24F is equipped with a twin-scroll Garrett MGT2260Z turbocharger. Complementing this setup is an air-to-air intercooler, a plastic intake manifold, and an electronic throttle body.
One notable enhancement over the FA20DIT is the inclusion of a stock liquid-to-liquid oil cooler, which helps manage engine temperatures more effectively—something the FA20DIT lacks.
4. FB20 (2011–Present 2.0L NA)
Used in the Impreza, Crosstrek, and other compact Subarus, the FB20 is an evolution of Subaru’s flat-four, built with efficiency and reliability in mind. It’s a low-stress engine that resists abuse from high mileage commuting and neglectful maintenance.
Timing chains replace belts, eliminating a major failure point. It won’t win races, but it survives hard city driving and long commutes with ease. In 2010, Subaru introduced the FB engine family, launching it with the flat-4 2.0-liter FB20 as a replacement for the iconic EJ20.
At first glance, the FB20 may look similar to its predecessor, but a deeper inspection reveals numerous updates both internally and externally. To better understand this 2.0L boxer engine, let’s explore its design, what’s new in its construction, and where its weaknesses lie.
The FB20 engine is built around a newly designed aluminum cylinder block. Unlike the EJ-series engine, the FB20 features a reduced piston bore—shrinking from 92.0 mm to 84.0 mm—but maintains its 2.0-liter displacement by increasing the stroke of the piston.

This longer stroke contributes to improved torque delivery at lower RPMs. To preserve the external dimensions of the older EJ-series block, Subaru implemented asymmetrical connecting rods in the FB20’s architecture.
Topping the engine are new dual overhead camshaft (DOHC) heads, each containing four valves per cylinder. One of the more significant design changes involves the reduced valve angle between the intake and exhaust valves, now 27 degrees compared to the EJ’s 41 degrees.
In addition, the spacing between the camshafts has been narrowed to 104.0 millimeters, down from the 126.0 millimeters seen in the EJ engines. This compact design was made possible by transitioning from a timing belt to chain-driven camshafts.
The narrower valve angle and smaller bore improve combustion efficiency during cold starts, which helps to lower emissions. Both the intake and exhaust camshafts are controlled by Subaru’s Dual AVCS (Active Valve Control System), providing variable valve timing for enhanced performance and efficiency.
The intake manifold, made of lightweight plastic, features a Tumble Generator Valve (TGV) system. This electronically controlled setup adjusts intake airflow dynamics to maximize fuel efficiency.
Subaru claims a 28% reduction in friction losses within the FB20, achieved through the use of lightweight pistons and connecting rods. These changes contribute to a 4% reduction in CO₂ emissions and a 10% improvement in fuel consumption.
Overall, the FB20 engine offers a more eco-friendly footprint than its predecessor while delivering the same power output and providing a broader torque curve. Compared to the EJ20, the FB20 represents a step forward in efficiency and emissions without sacrificing the performance expected from Subaru’s signature boxer layout.
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5. EZ30 (2001–2009 3.0L H6)
Subaru’s six-cylinder boxer, found in the Outback H6 and Legacy 3.0R, is overbuilt for its purpose. It features a timing chain, solid internals, and a smooth powerband.
While more complex than the EJ22, it doesn’t suffer from the chronic head gasket issues and is known for running well past 200,000 miles even when used in hot climates or mountainous regions.
Subaru began producing the 3.0-liter six-cylinder boxer engine, the EZ30, in 1999 as a replacement for the older EG33 motor. This engine was entirely developed from the ground up and was specifically designed for use in Subaru’s heavier vehicles, such as SUVs and other larger models.

The EZ30 features an aluminum cylinder block with a block height of 202 mm. Inside the block are cast iron sleeves with a thickness of 2 mm. The engine uses connecting rods that measure 131.5 mm in length and pistons with a compression height of 30.3 mm. Each of the two aluminum cylinder heads houses dual overhead camshafts (DOHC) and four valves per cylinder.
The lift of the exhaust and intake valves is 10.0 mm and 9.5 mm, respectively. The timing system is driven by two chains, with each chain operating the camshafts on one cylinder head. Additionally, this engine is equipped with an aluminum intake manifold featuring variable geometry.
In 2003, Subaru updated and refined the engine, resulting in the EZ30D (also referred to as the EZ30R). This revised version came with new cylinder heads featuring a variable valve timing system (AVCS) and an intake valve lift system known as AVLS. The valve lift varies depending on engine RPM: below 2000 rpm, between 2000–4000 rpm, and above 4000 rpm.
The EZ30R also introduced several other improvements, including an electronic throttle body with a diameter of 76 mm, a plastic intake manifold, a MAF (Mass Air Flow) sensor, and redesigned headers. It can take towing, steep hills, and high speeds in stride.
Subaru Engines That Can’t Take Heat
Subaru’s reputation has long ridden on the back of its signature boxer engines and rugged all-wheel-drive systems. For many, the brand stands for dependability, quirky charm, and snow-slaying capability.
But let’s be real—under the hood, not all Subaru engines are built the same. Some have earned a well-deserved reputation for going the distance, while others tend to buckle under pressure—literally.
1. EJ25D (1996–1999 DOHC 2.5L)
One of the most failure-prone engines Subaru ever built, the early EJ25D is infamous for its head gasket issues. The dual overhead cam design adds complexity and heat, but the cooling system often can’t keep up.
Overheating is common, and once it starts leaking coolant, things go downhill fast. It doesn’t take well to aggressive driving, hot climates, or prolonged abuse.
The Subaru EJ25D is a 2.5-liter flat-four engine that has established its place in the world of compact and mid-size vehicles. Renowned for its signature boxer configuration, this engine provides a low center of gravity, which plays a key role in enhancing handling and overall vehicle stability.

Thanks to its horizontally opposed cylinder layout, the EJ25D improves weight distribution and reduces engine vibration, resulting in a smoother driving experience. It belongs to Subaru’s iconic EJ engine family, a lineup known for combining durability with impressive performance characteristics.
Introduced in the mid-1990s, the EJ25D quickly became a mainstay in Subaru’s vehicle offerings. The engine is distinguished by its Dual Overhead Camshaft (DOHC) design and incorporates a variable valve timing system that enhances performance across a wide RPM range.
Engineered to strike a practical balance between power and fuel economy, the EJ25D appeals to a broad audience—from daily commuters looking for efficiency to driving enthusiasts who demand a more spirited performance from their Subaru.
2. EJ205 (2002–2005 WRX 2.0L Turbo)
The EJ205 was Subaru’s first turbocharged engine to hit U.S. WRX models. While fun, it suffers under abuse. The cast pistons and open-deck design mean it’s fragile when modified or driven hard in hot weather.
The small oil pan and inadequate intercooling compound heat issues, leading to ringland failures and overheating in track scenarios without upgrades.
The Enhanced Subaru WRX 2.0L DOHC EJ20 Turbo Long Block Engine is a professionally built, performance-focused powerplant designed for strength, reliability, and long-term durability. This custom-built engine requires your core for exchange, though stock units may be available—call for current availability or if you have specific questions.
Each build features new Safety Hyper-eutectic pistons fitted with precision rings, engineered to withstand the heat and pressure of turbocharged performance.

New King rod and main bearings are installed, along with fresh pin bushings to ensure proper wrist pin movement and minimal friction. The crankshaft is fully inspected, then ground (if needed) and polished to perfection. Connecting rods are reconditioned on both ends for balanced operation and longevity.
A complete gasket set is included, highlighted by high-performance 6-Star multi-layer steel (MLS) head gaskets designed to handle boost without failure. Cylinder heads are carefully inspected—valves and guides are replaced as needed, valve seats are re-cut to factory spec, and all components are brought back to proper spec for efficient flow and sealing.
A brand-new OEM timing kit is installed for exact camshaft timing, while a new water pump and oil pump are fitted to ensure consistent cooling and lubrication.
Before delivery, the long block is pre-spun on a simulation test machine to confirm oil pressure and verify rotational integrity. This engine comes backed by a 12-month or 12,000-mile warranty, giving you peace of mind whether you’re daily driving or hitting boost on the weekend.
3. FB25 (2011–2018 2.5L NA)
The naturally aspirated FB25 replaced the problematic EJ253, but introduced new issues. It’s known for excessive oil consumption and has a tendency to overheat when pushed hard, especially in warmer climates or during long uphill drives.
The CVT pairing in many models doesn’t help, often stressing the engine during extended climbs or when towing.
The Subaru FB25 is a 2.5-liter flat-four engine that marks a notable advancement in Subaru’s engineering approach. First introduced in 2010, it belongs to the FB engine family—renowned for blending performance with fuel efficiency.

Staying true to Subaru tradition, the FB25 features the brand’s signature boxer configuration, which positions the cylinders horizontally opposed. This engine layout lowers the vehicle’s center of gravity, enhancing handling and stability, while also reducing vibration for a smoother, more refined driving experience.
A key highlight of the FB25 is its Dual Overhead Camshaft (DOHC) setup, which improves airflow and performance across the RPM range.
Constructed with aluminum alloy for both the block and cylinder heads, the engine manages to maintain structural integrity while shedding unnecessary weight. Its 10.5:1 compression ratio helps strike a practical balance between power output and fuel economy, making it a strong performer in a wide range of driving scenarios.
Producing approximately 175 horsepower and 174 lb-ft of torque, the FB25 delivers sufficient power for most compact and midsize vehicles. It’s commonly mated to a continuously variable transmission (CVT), which not only enhances fuel efficiency but also ensures a smooth and consistent driving experience.
Altogether, the FB25 stands out as a dependable, well-rounded engine choice that suits both everyday driving and light-duty adventuring.
4. EE20 (2008–2020 2.0L Turbo Diesel – Global Markets)
Subaru’s foray into diesel with the EE20 was ambitious but flawed. It’s known for oil dilution, cracked DPFs, and poor thermal management.
The aluminum block and high compression ratio made it fragile under strain. While popular in Europe and Australia, it frequently fails under towing or extended high-speed use, especially in warm environments.
The Subaru EE20 engine is a compact yet potent 2.0-liter turbocharged diesel engine developed in response to the rising demand for fuel-efficient and performance-driven powertrains.
As part of Subaru’s acclaimed Boxer engine lineup, the EE20 inherits the hallmark horizontally opposed cylinder configuration. This setup not only aids in achieving a lower center of gravity—thereby improving vehicle stability—but also minimizes engine vibration, delivering a more composed and refined driving experience.

Engineered primarily with the European and Australian markets in mind, the EE20 quickly gained recognition for its strong fuel efficiency and torque-rich performance.
Producing approximately 147 horsepower and around 350 Nm of peak torque, it offers a well-rounded balance that suits both enthusiastic drivers and those focused on economy. Thanks to its turbocharged design, the engine provides brisk acceleration and flexibility, making it adaptable for various types of driving, whether navigating city streets or cruising at highway speeds.
The EE20 engine has been employed in several Subaru models that prioritize versatility and fuel efficiency. Among them is the Subaru Outback, where the EE20’s sturdy output and efficient design make it an ideal companion for both city commutes and off-road expeditions.
In the Subaru Forester, a model prized for its practicality and interior space, the diesel engine’s torque characteristics contribute to confident handling in a variety of driving and weather conditions.
The Subaru Legacy benefits from the EE20’s smooth power delivery, blending comfort with strong performance for those who appreciate a refined mid-size sedan experience. In hatchback and sedan forms, the Subaru Impreza leverages the EE20 to deliver a lively, engaging drive while maintaining excellent fuel economy.
Even the Subaru BRZ, typically known for its gasoline engines, has seen limited use of the EE20 in select markets, giving this sporty coupe a rare combination of diesel efficiency and dynamic handling.
In summary, the Subaru EE20 engine has earned a solid reputation within the diesel engine segment by offering a compelling mix of reliability, fuel efficiency, and real-world performance.
Its integration across a variety of Subaru vehicles underscores the brand’s dedication to thoughtful engineering and innovation, making the EE20 a notable player in the ongoing evolution of efficient internal combustion engines.
5. FA20DIT (2014–2021 2.0L Turbo – WRX, Forester XT)
The FA20DIT introduced direct injection and a twin-scroll turbo, improving efficiency but at the cost of heat tolerance. While it performs well, it suffers from carbon buildup and high combustion temperatures.
Overheating, detonation, and early turbo failure are common complaints among drivers who push the engine without upgraded oil coolers or tuning.
Stock tune knock events are frequent under hard acceleration in high heat. Subaru has produced engines that are either bulletproof or borderline fragile, depending on design era and application.
If you’re looking for a Subaru that can handle daily abuse, towing, or backroad thrashing, seek out models with the EJ22, EZ30, or FA24.
The FA20F engine, also known as the FA20DIT, was first introduced in 2012 in the Japanese market, powering the JDM Subaru Legacy 2.0GT DIT model. This 2.0-liter, four-cylinder boxer engine features direct fuel injection and a twin-scroll turbocharger, marking a significant step forward from the older EJ-series turbocharged engines like the EJ205 and EJ207.

The FA20F has since been implemented in other Subaru models, including the 2014 and newer Subaru Forester—badged as the Forester XT—and the 2015 and newer Subaru WRX. This naturally raises the question: how does it differ from the naturally aspirated FA20D found in the BRZ?
The FA20F/FA20DIT engine is based on the same naturally aspirated FA20 block. It utilizes an open-deck aluminum cylinder block with cast-in iron liners. The block contains cast pistons that are coated with an anti-friction skirt treatment and are connected to asymmetrical forged steel connecting rods. This rod design is specifically engineered to reduce friction and wear on both the cylinder walls and piston skirts during the compression stroke.
The turbocharged FA20 is also equipped with aluminum DOHC cylinder heads, each with eight valves (for a total of sixteen), roller rocker arms, and Subaru’s Dual AVCS system. The camshafts are driven by two single roller timing chains.
The intake valves measure 35 mm (1.38 inches), while the exhaust valves come in at 29 mm (1.14 inches). Notably, this engine’s valvetrain does not include hydraulic lifters, and the valve covers are constructed from aluminum alloy.
Fuel delivery is handled exclusively by a direct fuel injection system. Fuel is sprayed directly into the combustion chambers through injectors housed inside the heads. A high-pressure fuel pump, mounted on the left cylinder head and driven by the intake camshaft, supplies the necessary fuel pressure.
The intake manifold is constructed from plastic and incorporates a Tumble Generator Valve (TGV) system designed to enhance combustion efficiency.
On the exhaust side, an equal-length manifold routes gases into a centrally-located, low-mounted, twin-scroll Garrett MGT2259S turbocharger. Once compressed, the intake air is cooled via an air-to-air intercooler to ensure optimal performance and reliability.
The end result of this engineering is a noticeable leap in both power output and fuel efficiency when compared to earlier turbocharged engines. Some JDM-spec models equipped with the FA20F are capable of producing up to 296 horsepower and 295 pound-feet of torque.
But if you’re considering a used Subaru with an EJ25D or FA20DIT, approach with caution these engines can struggle when pushed and often fall apart under heat and neglect.
Maintenance is always key, but with Subaru, choosing the right engine can mean the difference between 300,000 worry-free miles or head gasket repairs before 100,000.