What is the Difference Between EJ255 and EJ257?

Introduction

When it comes to Subaru engines, the EJ255 and EJ257 are two popular options that enthusiasts often compare. Both engines have their own unique features and characteristics, making them suitable for different applications. In this article, we will explore the key differences between the EJ255 and EJ257 engines to help you understand their capabilities and make an informed decision.

EJ255 Engine

The EJ255 engine is a turbocharged boxer engine that was introduced by Subaru in 2004. It is primarily used in Subaru Impreza WRX models produced between 2006 and 2014. This engine features a displacement of 2.5 liters and utilizes a single-scroll turbocharger.

The EJ255 engine is known for its excellent power delivery and responsiveness. With its turbocharged setup, it generates impressive horsepower and torque figures, making it a popular choice among performance enthusiasts. It also benefits from Subaru’s advanced engine technologies, including Active Valve Control System (AVCS) and Subaru Intelligent Drive (SI-Drive), which enhance its overall performance.

EJ257 Engine

The EJ257 engine is another turbocharged boxer engine manufactured by Subaru. It is primarily found in high-performance Subaru models like the Impreza WRX STI, Legacy GT, and Forester XT. The EJ257 engine shares many similarities with the EJ255, but it boasts a larger displacement of 2.5 liters.

One of the key differences between the EJ255 and EJ257 engines is the presence of a semi-closed deck design in the EJ257. This design provides increased rigidity and strength to the engine block, making it more suitable for handling higher levels of power and performance modifications.

Performance Differences

While both the EJ255 and EJ257 engines offer impressive performance, there are some notable differences in their power outputs. The EJ255 engine typically produces around 265 horsepower and 244 lb-ft of torque, whereas the EJ257 engine delivers approximately 310 horsepower and 290 lb-ft of torque in stock form.

Furthermore, the EJ257 engine is often favored by performance enthusiasts due to its higher strength and robustness, making it more capable of handling increased boost pressure and aftermarket modifications. This engine is known for its ability to deliver exceptional power and performance, especially when paired with supporting modifications.

Compatibility and Swapping

Considering the similarities between the EJ255 and EJ257 engines, many people wonder if these engines are interchangeable or if it is possible to swap one for the other. While it is technically possible to swap these engines, it requires additional modifications and adjustments.

Due to the differences in engine management systems and supporting components, swapping an EJ255 engine into a vehicle originally equipped with an EJ257 (or vice versa) can be a complex task. It often involves reprogramming the engine control unit, modifying the wiring harness, and ensuring compatibility with the transmission and drivetrain components.

Conclusion

In summary, the EJ255 and EJ257 engines are both excellent choices for Subaru enthusiasts seeking performance and power. While the EJ255 offers great performance and responsiveness, the EJ257 takes it to the next level with its higher output and improved strength. If you are planning to modify your Subaru for increased performance, the EJ257 engine may be the more suitable option.

Frequently Asked Questions (FAQs)

1. Can I use an EJ255 engine in a Subaru WRX STI?

While it is technically possible to use an EJ255 engine in a Subaru WRX STI, it requires significant modifications and adjustments. It is generally recommended to stick with the EJ257 engine for optimal performance and compatibility.

2. Can I swap an EJ257 engine into a Subaru Impreza WRX?

Swapping an EJ257 engine into a Subaru Impreza WRX can be done, but it requires additional modifications and adjustments. It is crucial to ensure compatibility with the engine management system, wiring harness, and other supporting components.

3. Which engine is better for performance modifications?

The EJ257 engine is generally considered better for performance modifications due to its higher strength and ability to handle increased boost pressure. However, both engines can be modified to deliver impressive power and performance when paired with supporting upgrades.

4. Are there any reliability concerns with these engines?

While the EJ255 and EJ257 engines are generally reliable, it is important to note that modifications and aggressive tuning can affect their longevity. Proper maintenance, regular servicing, and using high-quality components are crucial to ensure the long-term reliability of these engines.

5. Can I increase the power of an EJ255 engine to match an EJ257?

It is possible to increase the power output of an EJ255 engine through modifications and tuning. However, reaching the same power levels as an EJ257 may require significant upgrades, such as a larger turbocharger, intercooler, fuel system, and engine internals.