Oldsmobile 305ci specs: 3.736 x 3.484 in (94.9 x 88.5 mm) bore and stroke, shared by all 4 versions. Displacement, compression and factory ratings.
| Displacement | 305 ci |
|---|---|
| Cylinders | 8 |
| Bore | 3.736" |
| Stroke | 3.484" |
| Compression | 9.8–9.9:1 |
| Advertised power | 145–170 hp |
| Years | 1978–1992 |
| Cylinder head data | 2 of 4 engines |
| Engine | Displacement | Bore × Stroke | CR | HP |
|---|---|---|---|---|
| Oldsmobile 305ci (1984) · 150 hp | 305 ci | 3.736" × 3.484" | 9.821:1 | 150 |
| Oldsmobile 305ci · 3.736" × 3.484" · 9.9:1 | 305 ci | 3.736" × 3.484" | 9.9:1 | 170 |
| LG3 | 305 ci | 3.736" × 3.484" | — | 145 |
| LG4 | 305 ci | 3.736" × 3.484" | — | 155–160 |
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.