The Subaru EJ205 Engine Manual

The Subaru EJ205 Engine Manual. Throughout Subaru’s history, the EJ engines have been a dynamic series. Subaru EJ engines were launched in 1989 to replace the Subaru EA engine series. Every EJ engine, including the Subaru EJ205, is a 16-valve horizontal flat-four with a single or double overhead camshaft. The EJ engines’ adaptability has made them exceedingly popular for engine swaps and various purposes outside of automobiles, including small aviation modifications. However, we will concentrate on the Subaru EJ205 engine and its overall value and dependability throughout this essay.

Outside of the Japanese market, the EJ205 was first seen in WRX vehicles. The 5-door Japanese WRX, on the other hand, did use the EJ205 for a brief period of time. Subaru found these engines to be big and high-quality enough to use in their popular Subaru WRX models from 1999 to 2006. From 1999 to 2001, Japanese vehicles also used the EJ207 engine. Check read our prior guide on the Subaru EJ207 for more information on the similar EJ engine type.

For the time being, we’ll look at some of the basic specs and overall benefits and downsides of the EJ205. How does this engine compare to the others in the EJ series, and what are some of the drawbacks that could detract from its total value? We answer those topics and go over 205’s history in further detail below. First, in the following section, we’ll go over some of the basic engine stats and design components for the Subaru EJ205 engine.

The Subaru EJ205 Engine Manual

Subaru EJ205 Engine Specifications

The Subaru EJ205 engine specifications are as follows:

The Subaru EJ205 Engine Manual

The Mitsubishi turbocharger and alternator of the EJ205 assist the engine produce 227 horsepower and 217 lb-ft of torque. These figures may not be impressive on paper, but the EJ205 offers outstanding power for its size and weight. However, there is sufficient power in a small package for several light aircraft layouts. At 7,000 rpm, the EJ205 engine reaches its redline. The aluminum block and head contribute to the engine’s total output while remaining relatively light.

The design of the Subaru EJ205, like that of the EJ207, is popular among modding enthusiasts. Proper upgrades and a decent tune may significantly increase the power of these engines (we’ll go over this in more detail in the sections below). There’s a reason the EJ205 is included in Subaru’s iconic WRX model; it’s a fantastic engine in terms of performance for its size. With that said, let’s take a look at the specific models that use the Subaru EJ205 engine, as well as the most popular upgrades and customization options.

EJ205 Subaru Applications

From 1999 until 2006, the Subaru EJ205 engine, which was initially introduced to the automotive market in 1999, was used in various WRX variants sold outside of Japan. First, from 1999 to 2001, the EJ205 was only available in JDM wagon body variants on the Subaru WRX. However, from 2001 to 2006, the EJ205 was installed in all JDM WRX variants. The Subaru EJ205 engine was also installed in the 2005 Saab 9-2X Aero. Finally, from late 1999 to 2001, and again in 2003, the EJ205 was used in Subaru’s Forester Cross Sports STI. The EJ205 engine would eventually be replaced by Subaru’s EJ255 engine, therefore ending manufacture of the 205.

Check out our previous post on the four most common problems with the Subaru EJ255 engine for more information on the EJ205’s successor. For the time being, let’s stick with the Subaru EJ205 engine and look at some of the more typical changes.

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Tuning and Modifications for the EJ205

The Subaru EJ engines are popular among vehicle modding enthusiasts because they respond well to appropriate modifications and a good tune. As a result, many WRX drivers with a 205 engine look for ways to increase power and overall performance with the help of helpful mods. EJ205 drivers may transform these lightweight engines into machines that create significant power for their size with a good balance of right mods and proper installation. However, with improper modifications and a lack of a good tune, enthusiasts may end up causing more harm than good to their EJ engines. As a result, it is critical to recognize that a decent tune is virtually always required for any modification effort. That being stated, some of the most popular mods for the EJ205 are listed below.

Importantly, finding components with perfect fitting is critical, but so is balancing out all supportive alterations and applying a suitable tune for any engine modification project to reach its maximum potential. So, here is our list of some of the most highly suggested Subaru EJ205 engine modifications:


Re-mapping is one of the least expensive upgrades one can do to their Subaru EJ205 engine. The process of modifying your engine’s CPU to expand the parameters of its performance potential is known as re-mapping. Furthermore, other aftermarket ECUs can be types of mapping that improve the overall performance value of the EJ205. Mapping, when combined with the appropriate supporting mods, may have an immediate and noticeable benefit for many Subaru owners looking for a performance bump.

Turbo/supercharger upgrades:

Upgraded turbochargers or superchargers, on the other hand, may be among the most expensive modification alternatives. They may, however, be the most effective in terms of immediately increasing power. enhanced air induction will undoubtedly increase your power, as would enhanced turbochargers or superchargers. As a result, boosting air supply allows more gasoline to be burned, resulting in more overall engine power.

Improved intake and exhaust systems:

Upgraded intake and exhaust system components can be critical for many custom engine projects because better airflow often implies improved power. However, it is vital to understand that an enhanced intake or exhaust will not significantly increase an engine’s overall output. However, an enhanced intake and exhaust can be excellent supportive mods for increasing airflow for your engine project. Overall, enhanced intake kits and upgraded exhaust systems will assist any custom project with substantial upgrades and tuning.

Improved road cameras and headwork:

Upgraded road cams may be the most dramatic improvement on our list for your engine, especially given the considerable mechanical changes that will occur when new road cams are installed. Many drivers may look into re-grinding a factory cam. However, if a decent solution is available on the market, many others may choose for the more expensive option of employing enhanced cams. Headwork, or improving headers, is another alternative for increasing an engine’s overall airflow. Improved headwork can reduce airflow restriction and turbulence, resulting in a more powerful engine.

Do these changes, however, have a significant impact on the overall reliability of your Subaru EJ205 engine? Yes, if they are not properly placed and balanced with adequate supportive mods and a good tune. However, with a thorough understanding of your engine’s capabilities, many drivers can construct a supremely efficient, more powerful EJ205. With that said, let’s take a closer look at the Subaru EJ205 engine’s dependability and durability below.

Subaru EJ205 Reliability and Common Issues

Subaru is working hard to improve its reputation for average or poor engine reliability and longevity. Despite this, many drivers believe that Subaru’s EJ engines are among the most robust and dependable available. Again, proper engine care and the use of high-quality oil will always improve and extend the life of any engine, including the Subaru EJ205. However, some issues are likely to arise with the EJ205 regardless of regular maintenance through time and wear.

Because of its turbocharger, the EJ205 is also known to require extensive care and maintenance. Unfortunately, water cooler problems appear to be more widespread than expected among EJ205 drivers. This issue appears to be limited to engine cylinder #4. Drivers should attempt to resolve this issue as soon as possible, before an engine strip-down and costly repairs are required. Finally, the Subaru EJ engines are notorious for their heavy oil consumption. Oil leaks and high oil consumption can be caused by a multitude of factors. Consistent oil changes and the use of high-quality oil are required to extend the life of the Subaru EJ205 engine.

Some of the issues listed above may never arise for many EJ205 drivers. However, these faults are rather prevalent and are expected to arise as drivers increase their mileage. In summary, the Subaru EJ205 engine has an acceptable to above-average overall reliability rating. However, the EJ205, like other engines, will have many additional issues if it is not properly maintained, is improperly modified, or is driven excessively.

The Subaru EJ205 Engine Manual

Summary of the Subaru EJ205 Engine Guide

Finally, the Subaru EJ205 engine deserves to be admired for its versatility and overall performance. This engine is popular among WRX drivers and Subaru enthusiasts due to its capacity to be developed into a more powerful project. It’s also difficult to dispute how diversified the EJ engines’ many applications may be, even outside of the iconic WRX model. The Subaru EJ205 succeeded the EJ207 and helped Subaru proceed into the modern automotive age with adaptability and affordability.

On paper, the EJ205 may not appear to be particularly powerful. However, considering their size and weight, and when compared to similarly-sized versions of the same age, these engines are extraordinarily powerful. The 205’s design contains some distinct flaws. Many of these issues, however, can be avoided with careful upkeep, repairs, and research. Any EJ engine project requires extensive research and comprehension of appropriate modifications and upgrades. It’s crucial to note that no excellent engine project is complete without adequate supporting mods and a good tune.

Subaru enthusiasts and many drivers worldwide continue to use the EJ205 for various engine swap projects or replacement engines. The WRX has established itself as one of Subaru’s most noteworthy cars, owing to the popularity of the EJ engine series. For some, the Subaru EJ205 can be an interesting project, while for others, it can be a fun and dependable daily driving. Regardless, the EJ205 engine’s impact on the global car market is difficult to discount.