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Subaru 82 NA specs: 1.8L (108.7 ci) 4-cylinder, 92 x 67 mm (3.6220 x 2.6378 in) bore and stroke, 9.5:1 compression. Rated 90 hp. Rod ratio and piston speed.
The Subaru 82 NA is oversquare — the 3.622" bore exceeds the 2.6378" stroke by 37.3% — a layout that favors airflow and RPM over leverage at the crank. The 2.6378" stroke does not reach 4,000 ft/min of mean piston speed until about 9,100 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 4 cylinders displaces 27.2 ci (445 cc).
9.5:1 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 10 engines in the EA family, sitting between the 59.6 ci and 110 ci members. Factory fitments include the Subaru Leone, Subaru XT, Subaru Loyale.
| Displacement | 108.7 ci / 1.8 L |
|---|---|
| Bore | 3.622" |
| Stroke | 2.6378" |
| Cylinders | 4 |
| Compression ratio | 9.5:1 |
| Bore/stroke ratio | 1.373 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | SOHC |
| Fuel type | gas |
| Advertised HP | 90 hp |
| Bore/stroke character | 1.373 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 2,638 ft/min — conservative for a street engine |
| Displacement per cylinder | 27.2 ci |
| Static compression | 9.5:1 — in the range that usually runs on pump premium |
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