See other engines in this family
Subaru EA-61 specs: 1.1L (66.4 ci) 4-cylinder, 76 x 60 mm (2.9920 x 2.3620 in) bore and stroke, 9:1 compression. Rated 55 hp. OHV. Rod ratio and piston speed.
The Subaru EA-61 is oversquare — the 2.992" bore exceeds the 2.362" stroke by 26.7% — a layout that favors airflow and RPM over leverage at the crank. The 2.362" stroke does not reach 4,000 ft/min of mean piston speed until about 10,150 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 4 cylinders displaces 16.6 ci (272 cc).
9:1 on aluminum heads is low by modern standards and generally happy on regular pump fuel.
It is one of 8 engines in the EA family, the smallest at 66.4 ci. Factory fitments include the Subaru FF-1 Star.
| Displacement | 66.4 ci / 1.1 L |
|---|---|
| Bore | 2.992" |
| Stroke | 2.362" |
| Cylinders | 4 |
| Compression ratio | 9:1 |
| Bore/stroke ratio | 1.267 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 55 hp |
| Bore/stroke character | 1.267 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 2,362 ft/min — conservative for a street engine |
| Displacement per cylinder | 16.6 ci |
| Static compression | 9:1 — low by modern standards, generally happy on regular pump fuel |
Each link opens the calculator with this engine's specs already filled in.