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Subaru EZ specs: 3.0L (183 ci) 6-cylinder, 89.2 x 80 mm (3.5118 x 3.1496 in) bore and stroke, 10.7:1 compression. Rated 212-245 hp. DOHC.
The Subaru EZ is oversquare — the 3.5118" bore exceeds the 3.1496" stroke by 11.5% — a layout that favors airflow and RPM over leverage at the crank. The 3.1496" stroke does not reach 4,000 ft/min of mean piston speed until about 7,600 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 6 cylinders displaces 30.5 ci (500 cc).
10.7:1 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 4 engines in the EZ family, the smallest at 183 ci. 5 factory variants share these dimensions, rated from 212 to 245 hp. Factory fitments include the Subaru Legacy Outback H6, Subaru Tribeca, Subaru Outback H6-3.0 and 10 others.
| Displacement | 183 ci / 3 L |
|---|---|
| Bore | 3.5118" |
| Stroke | 3.1496" |
| Cylinders | 6 |
| Compression ratio | 10.7:1 |
| Bore/stroke ratio | 1.115 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | gas |
| Advertised HP | 212–245 hp |
| Bore/stroke character | 1.115 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,150 ft/min — conservative for a street engine |
| Displacement per cylinder | 30.5 ci |
| Static compression | 10.7:1 — 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 |
|---|---|---|
| — | 212 hp | EZ30D |
| — | 212 hp | EZ30D |
| — | 212 hp | EZ30D |
| — | 212 hp | EZ30D, EZ30D (Gen 1) |
| — | 245 hp | EZ30R (Gen 2), EZ30R |