See other engines in this family
Subaru EJ257 specs: 2.5L (150.2 ci) 4-cylinder, 99.5 x 79 mm (3.9173 x 3.1102 in) bore and stroke. Rated 300-341 hp, 2004–2021. Used in the Subaru WRX. DOHC.
The Subaru EJ257 is oversquare — the 3.9173" bore exceeds the 3.1102" stroke by 26.0% — a layout that favors airflow and RPM over leverage at the crank. The 3.1102" stroke does not reach 4,000 ft/min of mean piston speed until about 7,700 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 4 cylinders displaces 37.6 ci (615 cc).
It is one of 37 engines in the EJ family, sitting between the 91.1 ci and 152 ci members. 20 factory variants share these dimensions, rated from 300 to 341 hp across 2004–2021.
| Displacement | 150.2 ci / 2.5 L |
|---|---|
| Bore | 3.9173" |
| Stroke | 3.1102" |
| Cylinders | 4 |
| Bore/stroke ratio | 1.26 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | gas |
| Advertised HP | 300–341 hp |
| Years | 2004–2021 |
| Bore/stroke character | 1.260 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,110 ft/min — conservative for a street engine |
| Displacement per cylinder | 37.5 ci |
Each link opens the calculator with this engine's specs already filled in.
These records share identical bore, stroke, displacement and compression. They differ by model year and factory power rating.
| Year | Advertised HP | Code |
|---|---|---|
| 2004 | 300 hp | EJ257 |
| 2005 | 300 hp | EJ257 |
| 2006 | 300 hp | EJ257 |
| 2007 | 300 hp | EJ257 |
| 2008 | 305 hp | EJ257 |
| 2009 | 305 hp | EJ257 |
| 2010 | 305 hp | EJ257 |
| 2011 | 305 hp | EJ257 |
| 2012 | 305 hp | EJ257 |
| 2013 | 305 hp | EJ257 |
| 2014 | 305 hp | EJ257 |
| 2015 | 305 hp | EJ257 |
| 2016 | 305 hp | EJ257 |
| 2017 | 305 hp | EJ257 |
| 2018 | 305 hp | EJ257 |
| 2018 | 310 hp | EJ257 |
| 2019 | 310 hp | EJ257 |
| 2019 | 341 hp | EJ257 |
| 2020 | 310 hp | EJ257 |
| 2021 | 310 hp | EJ257 |