Bore, stroke, displacement and compression for all 3 Cadillac HT4100 engines, compared side by side. Plus rod ratio and head specs where published.
| Displacement | 250–300 ci |
|---|---|
| Cylinders | 8 |
| Bore | 3.465–3.622" |
| Stroke | 3.307–3.622" |
| Compression | 8.5–9.5:1 |
| Advertised power | 135–200 hp |
| Engine | Displacement | Bore × Stroke | CR | HP |
|---|---|---|---|---|
| 49 V8 | 300 ci | 3.622" × 3.622" | 9.5:1 | 200 |
| 45 V8 | 273 ci | 3.622" × 3.3071" | 9:1 | 180 |
| V8 | 250 ci | 3.4646" × 3.3071" | 8.5:1 | 135 |
Both bore and stroke vary across the family, so these are separate castings rather than variations on one block.
1 of 3 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.