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Subaru Fa20 Turbo specs: 2.0L (122 ci) 4-cylinder, 86 x 86 mm (3.3858 x 3.3858 in) bore and stroke, 10.6:1 compression. Rated 268 hp. DOHC.
The Subaru Fa20 Turbo is exactly square — 3.3858" bore and 3.3858" stroke are the same — which splits the difference between a high-revving layout and a torque layout. The 3.3858" stroke does not reach 4,000 ft/min of mean piston speed until about 7,100 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 4 cylinders displaces 30.5 ci (500 cc).
10.6:1 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 11 engines in the FA family, sitting between the 121.9 ci and 146.5 ci members. Factory fitments include the Subaru WRX, Subaru Forester XT, Subaru Legacy.
| Displacement | 122 ci / 2 L |
|---|---|
| Bore | 3.3858" |
| Stroke | 3.3858" |
| Cylinders | 4 |
| Compression ratio | 10.6:1 |
| Bore/stroke ratio | 1 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | gas |
| Advertised HP | 268 hp |
| Bore/stroke character | 1.000 — square — bore and stroke are within 5%, a balanced compromise |
|---|---|
| Mean piston speed at 6,000 RPM | 3,386 ft/min — conservative for a street engine |
| Displacement per cylinder | 30.5 ci |
| Static compression | 10.6:1 — in the range that usually runs on pump premium |
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