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The Evolution of Subaru Engines: From Reliability to Innovation

Subaru is a well-known manufacturer of automobiles, renowned for producing reliable cars and innovative engineering. Although the company has been in existence for over 100 years, the production of the Subaru engine is a relatively new addition to the company’s repertoire.

In this article, we’ll delve into the history of Subaru engine manufacturing and highlight some of the production facilities currently in operation around the world.

History of Subaru Engine Manufacturing

Subaru’s journey in engine manufacturing began in the 1960s when the company decided to expand its operations by producing its own engines rather than relying on other manufacturers. In 1966, the EA engine was developed and launched, marking the beginning of Subaru’s foray into engine manufacturing.

Subaru’s engines were initially used solely in its own vehicles. However, the company soon began exporting its engines to other countries, primarily the

United States.

By the 1970s, Subaru engines were being installed in American-made vehicles, further solidifying the brand’s reputation for reliability. Throughout the next few decades, Subaru continued to produce new engine models, designing various engines for both passenger and commercial vehicles.

One of Subaru’s most well-known engines, the EJ20, was introduced in 1989. It was a four-cylinder engine, based on the EA82, but with a turbocharger.

The EJ20 powered many generations of WRX and STI models and was renowned for being reliable and powerful. Subaru continues to innovate in engine production, with its Boxer engine design being one of the hallmarks of the brand.

This engine design is unique, featuring horizontally-opposed pistons, which reduce vibration and create a smoother driving experience. While other manufacturers have attempted to replicate the Boxer engine design, none have been as successful as Subaru.

Subaru Engine Production Facilities Around the World

Subaru currently operates several production facilities around the world, primarily located in

Japan, the

United States, and

China. Let’s take a closer look at each of these facilities.


Subaru’s headquarters are located in

Japan, and it’s here that the majority of the company’s engines are produced. The Gunma Manufacturing Division, located in Ota-City, Gunma Prefecture,

Japan, produces all of Subaru’s engines for its domestic vehicles.

This facility is also responsible for the design and development of new engines, as well as the manufacture of various parts and components for Subaru’s vehicles.

United States

Subaru of Indiana Automotive (SIA) is located in Lafayette, Indiana, and is responsible for producing all of Subaru’s vehicles sold in North America. The facility produces the Ascent, Crosstrek, Impreza, Legacy, and Outback models, all of which feature engines produced in


However, SIA does play a critical role in engine manufacturing. The company builds the turbocharged 2.4-liter FA24 engine, which powers the Ascent, Legacy, and Outback models.

This engine is unique to the North American market and is not produced anywhere else in the world.



China, Subaru has partnered with Changan, a Chinese automobile manufacturer, to build cars and engines. The Changan Subaru engine plant, located in Jiangsu Province,

China, is responsible for producing engines for Subaru’s Chinese market cars.

The plant produces both Boxer and inline four-cylinder engines, with an annual production capacity of around 120,000 units per year.


Subaru has come a long way since its early days as an engine importer. The company’s commitment to innovation and reliability has made it a key player in the automobile industry.

With numerous production facilities around the world, Subaru is able to produce engines and cars to meet demand in various markets. From the early days of the EA engine to the turbocharged FA24 engine, Subaru continues to push boundaries and advance its engine manufacturing capabilities.

3. The Manufacturing Process of Subaru Engines

The manufacturing process of Subaru engines is a complex and highly detailed process.

It involves numerous steps, including design and development, casting, machining, assembly, and testing. Each step requires a high level of precision and attention to detail to ensure that the engine meets Subaru’s strict quality standards.

Design and Development

The first step in the manufacturing process of Subaru engines is the design and development phase. This involves the creation of computer-aided design (CAD) models based on the specific requirements of the engine.

The CAD models are used to create prototypes of the engine, where design engineers can test and refine the engine’s performance and reliability. Once the design phase is complete, the manufacturing process can begin.


The next step involves casting the engine block and cylinder heads. Cast iron and aluminum are commonly used materials for engine blocks, while aluminum is preferred for cylinder heads due to its lightness and excellent heat dissipation properties.

Subaru uses a combination of sand casting and die casting to produce engine components.

Sand casting involves creating a temporary mold out of sand, into which the molten metal is poured.

After the metal has cooled and solidified, the sand mold is removed, and the finished part is cleaned and inspected for quality. Die casting, on the other hand, involves injecting molten metal into a reusable steel die under high pressure.

Once the metal has cooled and solidified, the finished part is removed from the die, cleaned, and inspected for quality.


The next step in the manufacturing process is machining the cast components to their final shape and size. This involves using various machines, such as lathes, mills, and grinders, to remove any excess material and create the required geometry and surface finish.

Subaru uses automated machining centers for high-volume production, ensuring consistency and precision in the manufacturing process.


Once the components have been cast and machined, they are ready for assembly. This involves fitting the pistons, connecting rods, crankshaft, camshaft, and other parts together to create a complete engine.

The assembly line is highly automated, with robots and machines performing various tasks such as bolt tightening and torqueing, valve setting, engine balancing, and inspection. Each engine is assembled to precise specifications, and quality checks are carried out at every stage of the assembly process.


The final step in the manufacturing process is engine testing. This involves installing the completed engine into a test stand and subjecting it to a series of tests to ensure its performance, efficiency, and reliability.

These tests include measuring power output, fuel consumption, emissions, and noise levels. Engines that pass these tests are then ready for shipment to Subaru’s vehicle assembly plants.

4. Quality Control Measures Taken in the Production of Subaru Engines

Subaru is renowned for its high-quality engines, and the company takes quality control very seriously.

The Subaru manufacturing process includes numerous quality control measures designed to ensure that each engine meets the company’s rigorous standards.

Quality control begins with the casting process, where Subaru uses advanced computer simulations to optimize casting design and reduce the risk of defects.

Comprehensive checks are conducted during the casting process to ensure that the components meet Subaru’s dimensional and material standards. Once the cast components have been machined, they undergo a rigorous inspection process to ensure that they meet Subaru’s tolerances for shape, size, and surface finish.

This inspection is carried out using state-of-the-art coordinate measuring machines (CMM) that use lasers and other high-precision sensors to measure the components to within microns. The assembly process also includes numerous quality control measures.

Each component is checked again before assembly, and automated torque control systems ensure that bolts are tightened to the correct specifications.

Once the engine is assembled, it undergoes a series of rigorous tests to ensure that it meets Subaru’s requirements for performance, efficiency, noise levels, and emissions.

The results of these tests are recorded and stored, allowing for traceability and analysis if any issues arise. Subaru also conducts random spot checks on completed engines to ensure that all parts meet the company’s standards.

As well as complying with manufacturing and assembly standards, Subaru engines must meet strict environmental and safety standards, and the company is committed to reducing its carbon footprint by optimizing manufacturing processes and reducing waste.


The manufacturing process of Subaru engines is a highly technical and precise process that involves numerous steps and quality control measures. The company’s commitment to excellence in design, manufacturing, and quality control has led to the creation of some of the most reliable and durable engines on the market.

Through advanced manufacturing processes, innovative design, and rigorous quality control, Subaru continues to push the boundaries of engine technology and develop engines that set the standards for performance, reliability, and safety. 5.

Environmental Sustainability Practices in Subaru Engine Manufacturing

Subaru is committed to environmental sustainability and has implemented several practices in its engine manufacturing process to reduce its carbon footprint and environmental impact. These practices include:


Green Procurement: Subaru encourages its suppliers and partners to adopt eco-friendly practices and materials, such as using recycled or renewable materials in production. 2.

Waste Reduction: Subaru has implemented a zero-waste policy in its factories, meaning that they aim to recycle or otherwise repurpose all waste materials generated during production. This has resulted in a significant reduction in landfill waste.

3. Energy Management: Subaru has invested in energy-efficient lighting and heating systems, as well as renewable energy sources like solar panels.

This has led to reduced energy consumption and lower greenhouse gas emissions. 4.

Water Conservation: Subaru has implemented water-saving initiatives in its manufacturing process, such as using high-pressure cleaning systems that reduce water consumption while still maintaining cleanliness and hygiene. 5.

Environmental Management System: Subaru has a certified environmental management system in place to monitor and manage its environmental impact. The system includes regular audits and assessments to identify areas for improvement and ensure compliance with environmental regulations.

Subaru’s commitment to environmental sustainability is not limited to its engine manufacturing process but extends to its entire supply chain and operations. The company aims to be a leader in sustainable manufacturing practices and continues to implement innovative solutions to reduce its impact on the environment.

6. Advancements in Subaru Engine Technology

Subaru has a long history of innovation in engine technology, with a focus on combining performance, reliability, and efficiency.

Here are some of the latest advancements in Subaru engine technology:

1. Direct Injection: Subaru’s newest engines feature direct injection, which injects fuel directly into the combustion chamber for improved efficiency and power output.

Direct injection also allows for cleaner emissions, making Subaru engines more environmentally friendly. 2.

Turbocharging: Turbocharging has become a staple of Subaru’s engine lineup, providing increased power output while maintaining fuel efficiency. Turbocharged engines can deliver a significant increase in torque, making them ideal for performance-oriented models like the WRX and STI.

3. Auto Start-Stop: Auto Start-Stop is a technology that allows the engine to automatically turn off when the vehicle comes to a stop, such as at a traffic light or in traffic.

This helps to conserve fuel and reduce emissions, making it ideal for city driving. 4.

Cylinder Deactivation: Subaru’s newest engines feature cylinder deactivation, which shuts down one or more cylinders while cruising or idling to conserve fuel. This technology allows for improved fuel economy and reduced emissions without compromising performance.

5. Electric Hybrid: Subaru is currently working on its first electric-hybrid vehicle, which will feature a combination of electric and gasoline power.

The electric motor will provide added power and torque, while the gasoline engine will be used when the battery needs to be recharged, providing extended range. Subaru’s commitment to innovation in engine technology is evident in its range of high-performance and efficient engines.

Through the use of cutting-edge technologies like direct injection, turbocharging, and electric hybrid systems, Subaru continues to push the boundaries of what is possible in engine design and performance. 7.

Famous Subaru Engines in Motorsports

Subaru has made a significant impact in the world of motorsports, particularly in rally racing. The brand’s engines have proven to be powerful, reliable, and well-suited for the demanding conditions of competitive racing.

Here are some of the famous Subaru engines that have left their mark on motorsports:

1. Subaru EJ20: The EJ20 engine is one of Subaru’s most iconic engines and has been used extensively in rally racing.

Its turbocharged version, the EJ20T, powered the legendary Subaru Impreza WRX and Impreza WRX STI models in various rally championships. The EJ20’s exceptional power delivery, durability, and high-revving capabilities made it a favorite among rally drivers.

2. Subaru EJ25: The EJ25 engine, an evolution of the EJ20, has also been successful in motorsports.

This engine powered several generations of the Impreza WRX STI, dominating rally circuits around the world. Its larger displacement allowed for increased power and torque output, making it a force to be reckoned with on both asphalt and dirt.

3. Subaru FA20: The FA20 engine is a newer addition to Subaru’s engine lineup and has found success in motorsports, particularly in road racing and time attack events.

The FA20’s direct-injection technology, combined with its responsive turbocharging and reliable performance, has made it a popular choice for racing enthusiasts. It powers the Subaru BRZ, a sports car that shines in the world of track racing.

4. Subaru EG33: While not as widely used in motorsports as some of the other engines on this list, the EG33 is worthy of mention due to its unique characteristics.

The EG33 is a 3.3-liter flat-six engine used primarily in Subaru’s SVX sports coupe. Its smooth power delivery and distinctive sound have made it a favorite among enthusiasts, and some have even modified it for use in motorsports applications.

These engines have proven their mettle on rally stages, racetracks, and time attack courses, showcasing Subaru’s engineering excellence and commitment to performance. The reliability and power of these engines have contributed to Subaru’s success in motorsports, earning the brand a reputation for producing engines that excel in demanding racing environments.

8. The Impact of COVID-19 on Subaru Engine Production

The COVID-19 pandemic has had far-reaching effects on industries worldwide, and Subaru’s engine production has not been immune to its impact.

The following are some of the ways in which COVID-19 has affected Subaru’s engine production:

1. Disruption in Supply Chains: The pandemic caused significant disruptions in global supply chains, affecting the availability of components and materials necessary for engine production.

Subaru, like many other automakers, faced challenges in sourcing parts and maintaining a steady supply of raw materials, leading to temporary pauses or slowdowns in engine production. 2.

Manufacturing Facility Closures: To ensure the health and safety of their employees, Subaru, along with many other automobile manufacturers, temporarily closed their production facilities in response to local health guidelines and government restrictions. These closures resulted in a halt in engine production during those periods, leading to delays in fulfilling orders and meeting customer demand.

3. Reduced Demand: The COVID-19 pandemic caused a decrease in market demand for automobiles due to economic uncertainties and changing consumer behaviors.

This decline in demand impacted Subaru’s engine production, as the company had to adjust its production volume to align with market conditions. 4.

Implementation of Safety Measures: When production resumed, Subaru had to implement various safety measures in its facilities to prevent the spread of the virus among its employees. These measures included increased sanitation protocols, social distancing measures, and the adoption of remote work arrangements where possible.

These adjustments slowed down production and led to reduced capacity in order to prioritize the safety of the workforce. 5.

Recovery and Adaptation: Despite the challenges posed by the pandemic, Subaru, like many other automakers, adapted to the new normal. The company implemented strategies to navigate the crisis, including optimizing production processes, adjusting inventory levels, and finding alternative suppliers when necessary.

As the situation improves and demand begins to recover, Subaru’s engine production is expected to regain momentum. In summary, the COVID-19 pandemic has presented various challenges to Subaru’s engine production, including disruptions in supply chains, temporary facility closures, reduced demand, and the implementation of safety measures.

However, the company has demonstrated resilience and adaptability in the face of these challenges, working towards the recovery and continued production of high-quality engines that meet the needs of its customers. 9.

Subaru Engine Parts and Components Sourcing

Subaru’s engine manufacturing process relies on a vast network of suppliers and partners who provide the necessary parts and components for engine production. Subaru maintains stringent sourcing practices to ensure quality, reliability, and adherence to environmental and ethical standards.

Here is an overview of Subaru’s engine parts and components sourcing:

1. Pistons and Connecting Rods: Pistons and connecting rods are critical engine components that Subaru sources from specialized manufacturers.

These components must meet strict specifications in terms of weight, strength, and durability to ensure optimal engine performance and longevity. 2.

Crankshafts and Camshafts: Crankshafts and camshafts are responsible for converting linear motion into rotational motion in the engine. Subaru sources these components from suppliers who possess expertise in precision machining and metallurgy.

These parts are typically made from forged steel or high-strength alloys to withstand the stress and heat generated by the engine. 3.

Cylinder Heads and Blocks: Subaru’s cylinder heads and blocks are usually cast from aluminum or cast iron, depending on the engine model and required characteristics. These components play a crucial role in housing the pistons, valves, and other critical engine parts.

Subaru works with specialized foundries capable of producing high-quality castings to ensure the integrity and performance of these parts. 4.

Bearings and Seals: Bearings and seals are essential for minimizing friction and preventing oil leakage in the engine. Subaru sources bearings and seals from suppliers specializing in precision engineering and materials science.

These components are designed to withstand high temperatures, extreme pressures, and continuous rotation. 5.

Timing Belts and Chains: Subaru engines typically use timing belts or chains to synchronize the rotation of the crankshaft and camshaft, ensuring precise valve timing. Subaru sources these components from reputable suppliers who understand the importance of accuracy and durability in timing applications.

6. Fuel Injection Systems: Subaru’s modern engines employ advanced fuel injection systems for precise fuel delivery and optimal combustion.

Subaru partners with fuel system manufacturers to ensure the highest standards of performance and efficiency in these critical engine components. 7.

Exhaust Systems: Exhaust systems play a vital role in optimizing engine performance and emissions control. Subaru collaborates with exhaust system suppliers to design and manufacture systems that meet stringent regulatory requirements while enhancing both power output and sound characteristics.

Subaru maintains rigorous quality control measures throughout its supply chain to ensure that parts and components meet its exacting standards. This includes regular auditing, the establishment of long-term partnerships with trusted suppliers, and a commitment to environmental sustainability and ethical sourcing practices.

10. The Role of Subaru Engines in the Evolution of the Brand

Subaru engines have played a significant role in shaping the identity and reputation of the brand.

Throughout its history, Subaru has been known for its horizontally opposed “Boxer” engines – a design feature that has distinguished the brand from its competitors. The following aspects highlight the role of Subaru engines in the evolution of the brand:


Unique Engine Design: The Boxer engine, which features horizontally opposed pistons, is one of Subaru’s signature design attributes. This layout provides several advantages, including a lower center of gravity, reduced vibration, and improved handling characteristics.

Subaru’s commitment to the Boxer engine design has become synonymous with the brand and has been a key selling point for many Subaru enthusiasts. 2.

Performance and Reliability: Subaru engines, particularly those used in performance models like the Impreza WRX and WRX STI, have gained a reputation for their exceptional performance and reliability. The combination of turbocharging, advanced fuel injection systems, and meticulous engineering has resulted in engines capable of delivering impressive power outputs while maintaining durability – a crucial factor in Subaru’s success in motorsports and enthusiast communities.

3. All-Wheel Drive Capability: Subaru engines have played a significant role in the brand’s dedication to all-wheel drive (AWD) technology.

The horizontally opposed design of the engines allows for a symmetrical AWD system, which distributes power evenly to all wheels. This system provides superior traction, improved handling, and enhanced safety, making Subaru vehicles well-suited for adverse weather conditions and off-road driving.

4. Environmental Responsibility: Subaru has been a proponent of environmental responsibility, and its engines reflect this commitment.

The use of direct injection, turbocharging, and advanced combustion technologies in Subaru engines has led to improved fuel efficiency and reduced emissions. Additionally, Subaru has introduced hybrid electric powertrains in some models, showcasing its dedication to sustainable mobility and reducing its environmental impact.

5. Continuous Innovation: Subaru’s engines have continually evolved to incorporate new technologies and advancements.

The introduction of direct injection, cylinder deactivation, and hybrid powertrains demonstrates Subaru’s commitment to staying at the forefront of engine innovation. These advancements not only improve performance and efficiency but also contribute to Subaru’s overall brand identity as a technologically advanced automaker.

Subaru engines have played a pivotal role in the brand’s growth and success. The unique Boxer engine design, combined with high performance, reliability, AWD capability, and environmental responsibility, has solidified Subaru’s reputation as a manufacturer of dependable and enjoyable vehicles.

As the brand continues to innovate and adapt to changing market demands, Subaru engines will likely remain a cornerstone of the company’s success for years to come. 11.

The Importance of Proper Maintenance for Subaru Engines

Proper maintenance is essential for ensuring the longevity, performance, and reliability of Subaru engines. Regular maintenance not only helps prevent costly repairs but also maximizes fuel efficiency and minimizes the risk of breakdowns.

Here’s why proper maintenance is crucial for Subaru engines:

1. Longevity: Subaru engines are designed to be durable and long-lasting, but without regular maintenance, their lifespan can be significantly reduced.

Regular oil changes, filter replacements, and coolant flushes help remove contaminants and prevent engine wear, ensuring that the engine performs optimally for years to come. 2.

Performance: Proper maintenance enhances the performance of Subaru engines. Regularly replacing spark plugs, air filters, and fuel filters keeps the engine running smoothly, maintaining optimal fuel combustion and maximizing power output.

Ignoring maintenance can lead to decreased performance, reduced fuel efficiency, and sluggish acceleration. 3.

Reliability: Regular maintenance minimizes the risk of unexpected breakdowns and engine failures. Components such as belts, hoses, and ignition systems are prone to wear and tear over time.

By inspecting and replacing these components as needed, potential failures can be prevented, keeping the engine reliable and minimizing the chances of being stranded on the side of the road. 4.

Fuel Efficiency: A well-maintained engine operates more efficiently, resulting in improved fuel economy. Clean air filters allow for proper air intake, while fresh oil and appropriate oil viscosity help reduce friction in the engine.

Regular maintenance also ensures that fuel injectors and sensors are functioning optimally, resulting in accurate fuel delivery and better mileage. 5.

Resale Value: A well-maintained Subaru engine increases the resale value of the vehicle. Potential buyers are more likely to pay a higher price for a well-cared-for vehicle with documented maintenance records.

Regular maintenance shows that the engine has been taken care of properly, giving buyers confidence in its overall condition. To ensure proper maintenance of Subaru engines, it is recommended to follow the manufacturer’s maintenance schedule provided in the owner’s manual.

This schedule outlines specific intervals for routine maintenance tasks such as oil changes, filter replacements, fluid checks, and tune-ups. Additionally, it is important to have a reputable mechanic or Subaru dealer perform regular inspections and address any potential issues promptly.

12. Common Issues and How to Troubleshoot Subaru Engines

While Subaru engines are known for their reliability, they are not immune to occasional issues.

Understanding common problems and knowing how to troubleshoot them can help address issues promptly and minimize downtime. Here are a few common issues that owners of Subaru engines may encounter and some troubleshooting steps:


Overheating: Overheating can be caused by several factors, such as a coolant leak, a malfunctioning thermostat, or a failing radiator. If the engine temperature rises above the normal range, it is crucial to stop driving immediately to prevent further damage.

Check the coolant level, inspect for leaks, and ensure the cooling fans are functioning properly. If the issue persists, it is best to have a professional diagnose and repair the underlying cause.

2. Engine Misfires: Engine misfires can result in a rough idle, poor performance, and the illumination of the check engine light.

Common causes include faulty spark plugs, ignition coils, or fuel injectors. Inspect the spark plugs for signs of wear or fouling, and replace if necessary.

If the issue persists, it is advisable to have a mechanic diagnose the engine using diagnostic tools to identify the specific cause of the misfire. 3.

Oil Leaks: Oil leaks are relatively common in Subaru engines and can be caused by worn gaskets, seals, or oil pans. If an oil leak is detected, it is important to identify the source and address it promptly to prevent oil loss and potential engine damage.

Clean the engine and inspect the gaskets, seals, and oil pan for signs of leakage. Depending on the severity of the leak and the affected component, repairs may range from simple seal replacements to more extensive gasket replacements.

4. Electrical Issues: Electrical issues in Subaru engines may result in starting problems, intermittent power loss, or malfunctions of electronic components.

When faced with electrical problems, it is recommended to check the battery for corrosion, ensure proper connections, and inspect fuses and relays. If no obvious issues are detected, it may be necessary to use diagnostic equipment to identify specific electrical faults.

5. Timing Belt Failure: Some Subaru engines utilize timing belts that require periodic replacement.

If the timing belt fails, catastrophic engine damage can occur. It is crucial to adhere to the manufacturer’s recommended timing belt replacement intervals.

If the timing belt is worn, frayed, or showing signs of damage, it should be replaced immediately by a qualified technician. While these troubleshooting steps may offer initial guidance, it is important to consult with a professional Subaru mechanic or dealer for more accurate diagnosis and repairs.

Subaru-trained technicians have the knowledge and expertise to pinpoint specific issues and provide appropriate solutions, ensuring the longevity and performance of Subaru engines. Regular maintenance and prompt attention to any signs of trouble can help prevent more costly repairs and keep Subaru engines running smoothly for years to come.

13. Differences between Subaru Engines and Engines from Other Automakers

Subaru engines possess several distinct characteristics that set them apart from engines produced by other automakers.

These differences contribute to the unique driving experience, performance, and durability of Subaru vehicles. Here are some key factors that differentiate Subaru engines from engines made by other automakers:


Boxer Engine Configuration: One of the most notable features of Subaru engines is their Boxer engine configuration, also known as horizontally opposed engines. Unlike the more common inline or V-shaped engines, Subaru’s Boxer engines have cylinders that are horizontally opposed and lay flat.

This design results in a lower c

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