Learning More About Subaru Engines: The History of the EJ

To begin to learn the background details about this iconic engine, we need to go back a few decades and understand the position of Subaru engineers at this point in history. There became an increasing demand for more efficient vehicles powered by a more advanced, reliable but higher performing engine that could easily separate them from their competitors and keep their platforms unique. Their goal was not only to gain the attention of the average consumer, but also the above average enthusiast and seeker of an amplified driving lifestyle. As history has confirmed, the Subaru team embraced the challenge and successfully developed and delivered a design by the end of the 1980s called the  EJ series engine. Subaru enthusiasts have learned that the combined two letters (EJ) symbolize the specific family of engines, while the numerical ending is an indicator of the engine's displacement. This development proved to be a major engineering milestone for the automaker, proving their extreme value to the automotive world while opening the eyes of a wide range of drivers around the world. By 1996, Subaru had released a number of EJ family versions remaining consistent with their design structure but were differentiated over time by size and displacement while becoming a standard in their platforms represented in the marketplace. 

The EJ25, a 2.5L, naturally aspirated, flat-four boxer engine, made its first appearance in 1996 as the motor for Subaru's Legacy platform in the U.S. market. This gave the Legacy a "horizontally opposed" motor with all four cylinders configured in a flat, opposed arrangement allowing the vehicle to maintain better distribution of weight and a much lower center of gravity. Moreover, Subaru also configured this engine with a Dual Overhead Camshaft (DOHC) to give the vehicle improved fuel efficiency and increased performance. Subaru designed a valve train consisting of four valves per cylinder hydraulically actuated by lash adjusters along with timing belt driven camshafts. Lastly, in concert with its 2.5 liters of displacement, the engine's bore and stroke are 99.5 mm and 79 mm which delivers a balanced motor source that is both efficient and powerful. The most well-known and popular EJ25 motors began their reign after the premiere of Subaru's (GDB Chassis) Impreza WRX STIs at the midpoint of the 2000's when they hit the American market. Subaru has provided the marketplace with a non-turbocharged version of this motor, the EJ25D, but has also delivered the EJ25T, the turbocharged variant which has famously boosted the power and performance of the carmaker's WRX and STI platforms to leave a lasting impression with admirers and owners at all four corners of the globe.

With one stroke Subaru EJ25 engine checked all the boxes to satisfy the needs of a wanting consumer, the practical dreams of the daily driver, and the fantasies of serious performance pursuers within the enthusiasts realm. As serious enthusiasts know quite well, and others will soon learn, the iconic EJ25 power plant, primarily the turbocharged variant, has always exhibited an impressive list of power specifications, which specifically include a hefty pull of 305 horsepower and a stunning 290 lb-ft of torque, namely on the popular WRX STI platform. Power hungry enthusiasts who love speed, great lap times, and pulling away from their competition with ease also find that the acceleration from a EJ25 equipped pony does not hurt either. Drivers behind the wheel of a Subaru WRX STI have been famously clocked on a 0-60 mph run at a 5.3 second time and capture between 13 and 16 seconds in the quarter mile. In other Subaru platforms, the EJ25 proves itself to be all and more by giving the Legacy and Outback respectable numbers as well by delivering both an average rating of 170 horsepower and 174 lb-ft of torque while allowing the Legacy to hit 0-60 mph in 7.6 seconds. Subaru also had a mandate to provide the consumer with an engine that is proven to be more advanced, reliable, highly economical, and environmentally smart without losing quality, endurance, or personality in the process. Subaru successfully answered with the non-turbocharged variant of its EJ25 engine delivering up to 32 MPG on the highway while meeting all EPA standards with great emissions ratings.

As we have learned, Subaru has been providing a reliable, robust, and more than capable motor within the majority of its vehicles for over two decades. They have outfitted a world filled with a learned and encouraged tribe of creative performance followers with an example of engineering and design that opens doors into many rooms of ingenuity and wonder, truthfully than any other car manufacturer in history. It gives inspiration to an individual that wants to build upon something that already has a level of greatness out of the box. Namely it provides an engine that is equipped with a smartly designed and engineered four-cylinder configuration, a dual overhead cam valve train, and the option of both a turbocharged or non-turbocharged variant to someone who is aching to further enhance something that is already above and beyond the rest. An enthusiast who is investigating modifications on a vehicle, old or new, that is equipped with the EJ25 motor will be encouraged by the selection of aftermarket options, but will need to do some careful, experience informed research during their modification journey to ensure the most intelligent, appropriate choices are made to avoid major issues. They may look into new exhaust systems, intake options, turbocharger upgrades, and engine management, but it is important for any enthusiast to remember that any engine or performance modification that enhances power or alters the original engineered specifications can introduce stress and obstacles to the vehicles normal operating quality. These factors can negatively affect reliability, stability which, in some cases, may lead to permanent damage or costly failure. Every enthusiast should become accurately educated, make informed choices fueled by respected experts, and always consider the total cost and risk before modifying their EJ25 Subaru.

We have learned that the EJ25 has the specifications to support its popularity without sacrificing the balance of performance, efficiency, and practicality. Subaru has continually hit all their marks to ensure the EJ25 delivers a well supplied buffet of great power output, performance, gas mileage, and environmental protection. A realization of the born-in capability along with the enormous potential of Subaru's most popular power source gives even the most novice enthusiast a reason to dream and get inspired. It is important to realize that, along with all high performing, highly complex, and uniquely engineered engine designs, there is always the existence of issues, potential failures, and possible expense. Subaru did not provide the perfect engine with the release of the EJ25, so like with any performance motor, problems will arise if it is not carefully maintained and serviced to retain the capabilities that Subaru so proudly developed on the drawing board all those years ago. The enthusiast world has heavily researched, documented, and communicated issues experienced from its original release to the present day, but its popularity and dedicated advocate base will clearly confirm, Subaru's EJ25 has proven over the past decades of consumer use and motorsports activity to be one of the most reliable engines and performance providers available to the automotive world. Subaru vehicles equipped with the iconic EJ25 will continue to grace roadways, track days, international events, and take on challenges on the open trail for many years to come. The Subaru faithful would not have it any other way.

Subimods continues to concentrate on providing aftermarket innovations and products that take the Subaru platform of your choice to new levels in the present and the future, no matter if you choose a more exciting, dynamic daily drive, a more exhilarating weekend on the track, or a more aggressive adventure overland and in the wild.

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