Find your 2.5 Liter engine

2.5-Liter Engines: The most popular of Subaru’s engines is by far their 2.5-liter boxer-style four-cylinders. This 2.5-liter boxer engine first got its start in 1996 for the United States domestic market within the EJ engine class. The FB series 2.5-liter engine is the newer version of the older EJ-style 2.5-liter boxer motor. It should be noted that many enthusiasts consider the EJ25 the most prominent Subaru engine ever made.

• EJ25D - There were two versions of this engine with the first being the EJ25D produced in 1996 and the second being all the EJ25Ds produced in 1997 and after. The revised version of the EJ25D featured shimmed bucket lifts and was designed to run on 87-octane fuel whereas the first version was recommended to run on 91-octane fuel. This version of the EJ25 featured dual overhead cams (DOHC), a 10.7:1 compression, ratio, and a horsepower rating of 155-165hp. This engine was used in the 1998 Subaru Impreza 5 RS, the 1996-1999 Subaru Legacy GT, and the 1998 Subaru Forester.
• EJ251 - This was the first version of the single overhead cam (SOHC) variation of the EJ25 motor. This engine is known for head gasket failures which is why revised variations were produced in the years following. This 2.5-liter Subaru engine has a compression ratio of 10:1 and a horsepower rating of 165hp. It was used as a 2000-2003 Subaru Impreza engine, 2000-2004 Subaru Forester engine, 2000-2004 Subaru Legacy engine, and 2003-2005 Subaru Baja
• EJ252 - This was the second version of the single overhead cam (SOHC) variation of the EJ25 engine. This engine was essentially the same as the EJ251 but was made specifically for the 2000-2002 Subaru Legacy/ Outback with the manual transmission.
• EJ253 - This version of the 2.5-liter Subaru boxer engine made use of a MAF sensor unlike previous versions (EJ251) which used a MAP sensor. This engine also gained I-Active valves which are a variable valve lift (VVL) system on the intake side. This engine produced 175hp and was featured in the 2004-2011 Subaru Impreza, 2005-2012 Subaru Legacy, and the 05+ Subaru Baja. It should be noted this engine has an open deck design.
• EJ254 - This 2.5-liter turbocharged boxer engine is known for having dual overhead cams (DOHC) and an active valve control system (AVCS). It produced 164hp and was used in the 1998-2004 Subaru Forester.
• EJ255 - There are three versions of the EJ255 motor. The first version, which is used in the 2005-2006 Subaru Legacy and the 2004-2005 Subaru Forester, utilizes the exact heads and short block as the EJ257 engine that is used in the 2004-2006 Subaru Impreza WRX STI. The second version, however, uses a different short block dubbed the ‘AB630’ block as well as AB820 heads. The only difference in the block between this version and the EJ257 STI motor is the pistons. The third version, which was put in the 2010-2012 Subaru Legacy, has a dual-active valve control system (AVCS) and 9.5:1 compression ratio pistons. Overall, the EJ255 was used in the 2006-2014 Subaru Impreza WRX, the 2004-2013 Subaru XT, the 2005-2012 Subaru Legacy GT, the 2005-2009 Subaru Outback XT, the 2004-2006 Baja Turbo, and the 2006 Saab 9-2X. This engine was rated between 207-265hp from the factory.
• EJ257 - Known as the famous Subaru WRX STI motor, this engine has a following among car enthusiasts like no other. It features a dual overhead cam (DOHC) per cylinder design with a sequential multi-point fuel injection turbo. This 2.5-liter Subaru engine was built for performance and made a staggering 300-310hp straight off the production line. This engine was used in the 2004-2021 Subaru WRX STI as well as the Subaru Legacy GT, Subaru Outback ST, and Subaru Forester XT.
• FB25B - This is one of the newer versions of the 2.5-liter Subaru engines that features an oversquare bore and stroke design. It has a compression ratio of 10.0:1 and is rated at 170hp in the 2011-2018 Subaru Forester, the 2013-2019 Subaru Legacy, and the 2013-2019 Subaru Outback.
• FB25D - This is the newer version of the FB25B motor that comes with direct fuel injection for added horsepower and fuel efficiency. This motor debuted in 2019 with a compression ratio of 12.0:1 and a horsepower rating of 182hp. This engine is currently used in the 2019-present Subaru Forester, 2020-present Subaru Legacy, 2020-present Subaru Outback, and 2021-present Subaru Crosstrek.