GMC 454ci specs: 4.251 x 4.00 in (108 x 101.6 mm) bore and stroke, shared by all 3 versions. Displacement, compression and factory ratings, plus rod ratio.
| Displacement | 454 ci |
|---|---|
| Cylinders | 8 |
| Bore | 4.251" |
| Stroke | 4.000" |
| Compression | 8.0–9.0:1 |
| Advertised power | 205–290 hp |
| Years | 1973–2000 |
| Engine | Displacement | Bore × Stroke | CR | HP |
|---|---|---|---|---|
| GMC 454ci (1973–1978) | 454 ci | 4.251" × 4" | 8:1 | 205 |
| LF8 | 454 ci | 4.251" × 4" | 8:1 | — |
| L29 | 454 ci | 4.251" × 4" | 9:1 | 290 |
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.