Top Ten Engines | Inside The Engines That Powered An Industry

8| Subaru EJ257

Scoobie Power With A Rally Heritage…

Example of a the Subaru EJ257 engine

The Subaru EJ257 engine hails from a rally heritage that started when Subaru began competing in rally in 1980. Unlike the JDM STI’s 2-liter EJ207 engine, the EJ257 was designed for the USDM 2004 Impreza WRX STI. The EJ257 features a horizontally opposed four-cylinder configuration, to help lower the center of gravity of the engine and the overall chassis configuration. The big bores and relatively short stroke of the 2.5-liter engine produce tremendous torque in stock form. Subaru’s Active Valve Control System (AVCS) adds variable valve timing to the intake valves. The ECU-controlled intake camshaft can be adjusted up to 35 degrees, optimizing intake cam timing throughout the RPM range. An IHI turbocharger supplies the boost pressure that helps the big 2.5-liter engine generate 300 bhp and 290 lb-ft torque, ideal for an all-wheel drive application. However, the EJ257 does suffer from a few shortcomings. The biggest drawback is poorly manufactured pistons with weak ring lands. Piston failures due to broken ring lands have been found to be the cause of a number of blown engines. Some also find the boxer’s inherently awkward sound to be annoying and inescapable. But it’s not always considered a bad thing, since legions of Subie loyalists live for its unique exhaust note.


What’s Hot:Example of a the Subaru EJ257 engine

• Low center of gravity
• Big displacement
• Factory turbocharged
• High power output
• High torque output
• Lightweight
• Compact design
• Variable valve timing

What’s Not:Example of a the Subaru EJ257 engine

• Factory pistons prone to failure when pushed
• Hard to work on – upgrading head gaskets or camshafts require engine removal
• Top-mounted intercooler susceptible to heat soak
• Awkward sound due to boxer engine and unequal-length manifold design
• Boxer design requires higher degree of machining precision


Manufacturer: Subaru
Years In Production: 2004-Present
Engine Code: EJ257
Displacement (cc): 2,457cc
Bore & Stroke (mm): 99.5mm x 79mm
Peak Horsepower (@ RPM): 300 bhp @ 6,000 RPM
Peak Torque (@ RPM): 290 lb-ft @ 4,000 RPM
Block Material: Aluminum
Head Material: Aluminum
Compression Ratio: 8.2:1
Camshafts: 256-degree (IN & EX)
Valves / Springs / Retainers: 16 Valve, AVCS Variable Valve Timing System
Throttle Body: Single
Fuel Injectors: Side Feed, High Impedance, 565 cc/min (x4)
Ignition System: Coil-on-plug
Applications: 2004-2007 Subaru Impreza WRX STi (GDB)
2008-2012 Subaru Impreza WRX STi (GRB)
2011-2012 Subaru Impreza WRX STi (GVB)