Volvo 121ci specs: 88.9 x 80 mm (3.5000 x 3.1496 in) bore and stroke, shared by all 3 versions. Displacement, compression and factory ratings, plus rod ratio.
| Displacement | 121 ci |
|---|---|
| Cylinders | 4 |
| Bore | 3.500" |
| Stroke | 3.150" |
| Compression | 8.7–10.5:1 |
| Advertised power | 118–130 hp |
| Years | 1969–1975 |
| Engine | Displacement | Bore × Stroke | CR | HP |
|---|---|---|---|---|
| B20F | 121 ci | 3.5" × 3.1496" | 8.7:1 | 125 |
| B20B | 121 ci | 3.5" × 3.1496" | 9.3:1 | 118 |
| B20E | 121 ci | 3.5" × 3.1496" | 10.5:1 | 130 |
Compression spans 8.7:1 to 10.5:1, so fuel requirements differ meaningfully between members — worth checking before assuming parts interchange.
All are oversquare — bore larger than stroke, which favours revs over low-end torque.
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.