Mercury 255ci specs: 3.188 x 4.00 in (81 x 101.6 mm) bore and stroke. Displacement, compression and factory ratings for each, plus rod ratio and piston speed.
| Displacement | 255 ci |
|---|---|
| Cylinders | 8 |
| Bore | 3.188" |
| Stroke | 4.000" |
| Compression | 7.2:1 |
| Advertised power | 125 hp |
| Years | 1952–1953 |
| Engine | Displacement | Bore × Stroke | CR | HP |
|---|---|---|---|---|
| Mercury 255ci (1952–1953) | 255 ci | 3.1875" × 4" | 7.2:1 | 125 |
This family is represented by a single engine in the database: 255 ci, 8 cylinders, a 3.1875" × 4" bore and stroke.
All are undersquare — stroke larger than bore, favouring torque low in the range.
Each engine page carries rod ratio, mean piston speed, bore/stroke character and cylinder head specs where published, and links into the calculators with its dimensions already filled in.