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Subaru EJ253 specs: 2.457L (150 ci) 4-cylinder, 99.5 x 79 mm (3.9173 x 3.1102 in) bore and stroke, 10:1 compression. Rated 165-175 hp, 2004–2012.
The Subaru EJ253 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 37.5 ci (615 cc).
10:1 on aluminum heads is in the range that usually runs on pump premium; aluminum sheds heat faster than iron, which makes the same number a little more forgiving.
It is one of 43 engines in the EJ family, sitting between the 91.1 ci and 152 ci members. 13 factory variants share these dimensions, rated from 165 to 175 hp across 2004–2012.
| Displacement | 150 ci / 2.457 L |
|---|---|
| Bore | 3.9173" |
| Stroke | 3.1102" |
| Cylinders | 4 |
| Compression ratio | 10:1 |
| Bore/stroke ratio | 1.26 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | SOHC |
| Fuel type | gas |
| Firing order | 1-3-2-4 |
| Advertised HP | 165–175 hp |
| Years | 2004–2012 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. |
|---|---|---|---|---|
| 2005 | EJ253 net | 168 @ 5600 | 166 lb-ft @ 4000 | 10:1 |
| 2006 | EJ253 net | 173 @ 6000 | 166 lb-ft @ 4400 | 10:1 |
| 2006 | EJ253 net | 175 @ 6000 | 169 lb-ft @ 4400 | 10:1 |
| 2007 | EJ253 net | 173 @ 6000 | 166 lb-ft @ 4400 | 10:1 |
| 2007 | EJ253 net | 175 @ 6000 | 169 lb-ft @ 4400 | 10:1 |
| 2008 | EJ253 net | 170 @ 6000 | 170 lb-ft @ 4400 | 10:1 |
| 2008 | EJ253 net | 173 @ 6000 | 166 lb-ft @ 4400 | 10:1 |
| 2009 | EJ253 net | 170 @ 6000 | 170 lb-ft @ 4400 | 10:1 |
| 2010 | EJ253 net | 170 @ 6000 | 170 lb-ft @ 4400 | 10:1 |
| 2011 | EJ253 net | 170 @ 6000 | 170 lb-ft @ 4400 | 10:1 |
| 2012 | EJ253 net | 170 @ 5600 | 170 lb-ft @ 4000 | — |
Factory specification sheet.
| 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 |
| Static compression | 10:1 — in the range that usually runs on pump premium |
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 | 165 hp | EJ253 |
| 2005 | 165 hp | EJ253 |
| 2005 | 168 hp | EJ253 |
| 2006 | 173 hp | EJ253 |
| 2006 | 175 hp | EJ253 |
| 2007 | 173 hp | EJ253 |
| 2007 | 175 hp | EJ253 |
| 2008 | 170 hp | EJ253 |
| 2008 | 173 hp | EJ253 |
| 2009 | 170 hp | EJ253 |
| 2010 | 170 hp | EJ253 |
| 2011 | 170 hp | EJ253 |
| 2012 | 170 hp | EJ253 |
5 factory vehicles, 2000–2012. Each year opens that model's engine table.