Is an EJ25 an STi engine?
The EJ25 engine is a well-known powerplant in Subaru's lineup, but there is often confusion about whether it is specifically an STi engine. In this article, we’ll explore the details of the EJ25 engine, its applications, and whether it is synonymous with the STi performance models.
What is the EJ25 Engine?
The EJ25 is a 2.5-liter, horizontally opposed (boxer) four-cylinder engine produced by Subaru. It has been used in a variety of Subaru models over the years, including the Impreza, Legacy, Forester, and Outback. Known for its balance and compact design, the EJ25 has become a staple in Subaru's lineup, offering a mix of reliability and performance.
Is the EJ25 Exclusive to the STi?
No, the EJ25 is not exclusive to the Subaru STi. While the EJ25 engine is used in the STi, it is also found in other Subaru models. However, the version of the EJ25 used in the STi is significantly different from the versions found in non-STi models. Here’s why:
- Performance Tuning: The EJ25 in the STi is heavily tuned for high performance, featuring upgrades such as a larger turbocharger, forged internals, and advanced engine management systems.
- Durability Enhancements: The STi version of the EJ25 is built to handle higher stress levels, making it more robust for spirited driving and motorsport applications.
- Unique Features: The STi variant often includes features like a semi-closed deck design for added strength, which is not present in the standard EJ25 engines used in other Subaru models.
How to Identify an STi EJ25 Engine
If you’re trying to determine whether an EJ25 engine is from an STi, here are some key indicators:
- Engine Code: The engine code for the STi EJ25 is typically EJ257, while non-STi versions may have different codes such as EJ253 or EJ255.
- Turbocharger: STi models feature a larger turbocharger compared to non-STi turbocharged EJ25 engines.
- Intercooler: The STi version often comes with a top-mounted intercooler that is larger and more efficient than those found in other models.
- Performance Output: The STi EJ25 produces significantly more horsepower and torque compared to its non-STi counterparts.
Conclusion
While the EJ25 engine is used in the Subaru STi, it is not exclusive to it. The STi version of the EJ25 is a high-performance variant with numerous upgrades that set it apart from the standard EJ25 engines found in other Subaru models. If you’re considering an EJ25 engine for a project or purchase, understanding these differences is crucial to ensure you get the performance and features you’re looking for.
Frequently Asked Questions
When did Subaru stop using the EJ25?
Subaru's flagship model the WRX and STI have all been powered by this engine series until 2015 when the WRX name dropped the EJ25 and added a BRZ variant of Subaru's new motor the FA series.
What makes a Subaru an STI?
These letters stand for Subaru Tecnica international, which is essentially a name to describe Subaru's own motorsports program.
Are WRX and STI the same engine?
However, the WRX has neither the same motor, or drivetrain and differentials as the STi. The STi receives a 2.5l turbocharged flat four making ~300 horsepower at the crank while the WRX historically has received a 2.0l turbocharged flat four making between 227 and 268 horsepower at the crank.
What engine is in an STI?
| Subaru WRX STI | |
|---|---|
| Related | Subaru WRX |
| Powertrain | |
| Engine | Petrol: 2.0 L EJ207 H4-T (JDM) 2.5 L EJ257 H4-T (export) |
| Transmission | 6-speed TY85 manual |
What's the difference between EJ25 and EJ257?
In the US, the only car that has an engine designated as an EJ257 is the STI. All of the other 2.5 liter turbo EJ series engines are designated EJ255.
What does STi stand for?
Sexually transmitted infections (STIs), or sexually transmitted diseases (STDs), are infections that are passed from one person to another through sexual contact. They are usually spread during vaginal, oral, or anal sex.
What is the weakness of the EJ25?
No engine is perfect, and the EJ25 is no exception. Some common issues that EJ25 owners have reported include head gasket failures, ringland failures, oil consumption issues, and timing belt and water pump failures.
What is the difference between a STD and a STI?
A sexually transmitted infection (STI) is a virus, bacteria, fungus, or parasite people can get through sexual contact. A sexually transmitted disease (STD) develops because of an STI and the term implies that the infection has led to some symptom of disease. People sometimes use the terms in one another's place.
How much HP can a EJ25 handle?
300 whp:The EJ20/EJ25 engines can handle 300 whp maximum with stock internals with no further modifications other than a proper fuel management tune. 400 whp:We suggest a set of forged AMR pistons and billet rods to safely boost up the engine.
Is an STI still a WRX?
At the launch of the current WRX in 2022, the car maker announced Subaru Technica International (STI) would not be producing a high-performance version of the WRX – with the department instead shifting its focus to electric cars. Subaru then trademarked the STe badge in 2023.
