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Honda EK1 specs: 1.8L (107 ci) 4-cylinder, 77 x 94 mm (3.0315 x 3.7008 in) bore and stroke. Rated 72-75 hp, 1979–1983. Used in the Honda Accord.
The Honda 107ci (EK1) is undersquare — the 3.7008" stroke exceeds the 3.0315" bore by 18.1% — a layout that trades peak RPM for leverage and torque low in the range. The 3.7008" stroke puts mean piston speed at 4,000 ft/min around 6,500 RPM, which is where a production bottom end is generally considered at its limit. Each of the 4 cylinders displaces 26.8 ci (438 cc).
6 factory variants share these dimensions, rated from 72 to 75 hp across 1979–1983.
| Displacement | 107 ci / 1.8 L |
|---|---|
| Bore | 3.0315" |
| Stroke | 3.7008" |
| Cylinders | 4 |
| Configuration | I4 |
| Compression ratio | 8–8.8:1 (published figures vary) |
| Bore/stroke ratio | 0.819 |
| Fuel type | gas |
|---|---|
| Advertised HP | 72–75 hp |
| Years | 1979–1983 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. |
|---|---|---|---|---|
| 1979 | EK1 net | 72 @ 4500 | 94 lb-ft @ 3000 | 8:1 |
| 1980 | EK1 net | 72 @ 4500 | 94 lb-ft @ 3000 | 8:1 |
| 1981 | EK1 net | 75 @ 4500 | 95.8 lb-ft @ 3000 | 8.8:1 |
| 1982 | EK1 net | 75 @ 4500 | 95.8 lb-ft @ 3000 | 8.8:1 |
| 1983 | EK1 net | 75 @ 4500 | 95.8 lb-ft @ 3000 | 8.8:1 |
Factory specification sheet.
| Bore/stroke character | 0.819 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 3,701 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 26.8 ci |
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 |
|---|---|---|
| 1979 | 72 hp | EK1 |
| 1980 | 72 hp | EK1 |
| 1981 | — | EK1 |
| 1981 | 75 hp | EK1 |
| 1982 | 75 hp | EK1 |
| 1983 | 75 hp | EK1 |
2 factory vehicles, 1979–1983. Each year opens that model's engine table.