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The Specs and Reliability of the Subaru EJ25 Engine - Part 1 -

The Specs and Reliability of the Subaru EJ25 Engine - Part 1

Subaru is known for its reliable and powerful engines, and the EJ25 is no exception. This engine has been a staple in Subaru vehicles since 1996 and has proven to be a popular choice for car enthusiasts and everyday drivers alike. In this article, we will take a closer look at the specs and reliability of the Subaru EJ25 engine.

When choosing a vehicle, it's important to consider the engine specs. The engine is the heart of the car, and it's the component that provides power and performance. That said, it definitely has a lot to offer, so let's dive into the details.

The Design of the EJ25 Engine

The EJ25 engine is a four-cylinder, horizontally opposed engine. This means the cylinders are arranged in a flat, opposed configuration, providing a low center of gravity and better weight distribution. The engine is also designed with a double overhead camshaft (DOHC) configuration, which provides better performance and fuel efficiency than single overhead camshaft (SOHC) engines.

It has a displacement of 2.5 liters, which is where it gets its name. The bore and stroke of the engine are 99.5 mm and 79 mm, respectively. This configuration provides a good balance of power and efficiency, making it a popular choice for Subaru vehicles.

Valve train specifications include four valves per cylinder, which are actuated by hydraulic lash adjusters. The camshafts are driven by a timing belt, which should be replaced every 100,000 miles to prevent engine damage.

The EJ25 engine is available in both turbocharged and non-turbocharged variations. The turbocharged version, known as the EJ25T, is found in the WRX and STI models and provides impressive power and performance. The non-turbocharged version, known as the EJ25D, is found in other Subaru models and provides a more balanced approach to power and efficiency.

Power Ratings and Performance

The EJ25 engine has impressive power ratings, especially in the turbocharged version. The EJ25T produces 305 horsepower and 290 lb-ft of torque in the WRX STI model. The non-turbocharged version produces 170 horsepower and 174 lb-ft of torque in the Legacy and Outback models.

In terms of performance, the EJ25 engine is capable of impressive acceleration times. The WRX STI can go from 0-60 mph in just 5.3 seconds, while the Legacy can do it in 7.6 seconds. The quarter-mile times for these vehicles are 13.7 seconds and 15.9 seconds, respectively.

Fuel economy and emissions ratings are also important considerations for many drivers. The EJ25 engine provides decent fuel economy, with the non-turbocharged version getting up to 32 MPG on the highway. Emissions ratings are also good, with the engine meeting all EPA standards.

Common Modifications and Upgrades

As with any engine, several aftermarket parts and modifications are available for the EJ25. Some of the most common upgrades include intake and exhaust systems, turbocharger upgrades, and engine management systems. These upgrades can provide significant increases in power and performance, but they can also come with some drawbacks.

One of the main concerns with modifications is reliability. While some modifications can increase power and performance, they can also put additional stress on the engine and other components. This can lead to increased wear and tear, decreased reliability, and even engine failure in some cases.

Another consideration when modifying the EJ25 engine is cost. High-performance parts and upgrades can be expensive, and the cost can quickly add up. It's essential to consider the cost-benefit ratio when deciding which modifications to make.


The Subaru EJ25 engine is a strong and reliable engine used in many Subaru cars for over 20 years. It is a good mix of power and efficiency. It has a well-designed cylinder layout, a DOHC valve train, and both turbocharged and non-turbocharged versions.

When looking at engine specs, it's important to look at the power, performance, gas mileage, and pollution ratings. The EJ25 engine gets good ratings in all of these areas, making it a good choice for drivers who want a reliable and powerful engine.

Indeed, the Subaru EJ25 engine is a reliable and powerful engine that will always be a popular choice for both car enthusiasts and regular drivers.

If you are looking for a great source of Subaru engine add-ons online, look no further than our amazing selection here at Subimods. We are the leading supplier of Subaru performance parts, aftermarket parts, replacement parts, and accessories. Check out our online store for more of our available car parts and their prices.

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