Oldsmobile 231ci specs: 3.80 x 3.40 in (96.5 x 86.4 mm) bore and stroke, shared by all 6 versions. Displacement, compression and factory ratings.
| Displacement | 231 ci |
|---|---|
| Cylinders | 6 |
| Bore | 3.800" |
| Stroke | 3.400" |
| Compression | 9.3–10.3:1 |
| Advertised power | 115–205 hp |
| Years | 1982–1993 |
| Cylinder head data | 4 of 6 engines |
| Engine | Displacement | Bore × Stroke | CR | HP |
|---|---|---|---|---|
| Oldsmobile 231ci (1982) · 115 hp | 231 ci | 3.8" × 3.4" | 9.321:1 | 115 |
| Oldsmobile 231ci · 3.800" × 3.400" · 9.5:1 | 231 ci | 3.8" × 3.4" | 9.5:1 | 135–150 |
| Oldsmobile 231ci · 3.800" × 3.400" · 9.8:1 | 231 ci | 3.8" × 3.4" | 9.8:1 | 165–205 |
| Oldsmobile 231ci (1993) · 170 hp | 231 ci | 3.8" × 3.4" | 10.3:1 | 170 |
| LG2 | 231 ci | 3.8" × 3.4" | — | 125 |
| LG3 | 231 ci | 3.8" × 3.4" | — | 150 |
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.