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Cadillac 331ci (1953–1955) specs: 331 ci 8-cylinder, 3.813 x 3.625 in (96.8 x 92.1 mm) bore and stroke. Rated 210-270 hp, 1953–1955.
The Cadillac 331ci (1953–1955) is oversquare — the 3.8125" bore exceeds the 3.625" stroke by 5.2% — a layout that favors airflow and RPM over leverage at the crank. The 3.625" stroke puts mean piston speed at 4,000 ft/min around 6,600 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 41.4 ci (678 cc).
3 factory variants share these dimensions, rated from 210 to 270 hp across 1953–1955.
| Displacement | 331 ci |
|---|---|
| Bore | 3.8125" |
| Stroke | 3.625" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 8.25–9:1 (published figures vary) |
| Bore/stroke ratio | 1.052 |
| Fuel type | gas |
|---|---|
| Advertised HP | 210–270 hp |
| Years | 1953–1955 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. | Duration int / exh | Valve lift int / exh | LSA |
|---|---|---|---|---|---|---|---|
| 1953 | gross | 210 @ 4150 | 330 lb-ft @ 2700 | 8.25:1 | 269° / 270° | 0.365" | 110.25° |
| 1954 | gross | 230 @ 4400 | 330 lb-ft @ 2700 | 8.25:1 | 269° / 270° | 0.365" | 110.25° |
| 1955 | gross | 270 @ 4800 | 345 lb-ft @ 3200 | 9:1 | 269° / 270° | 0.411" | 110.25° |
Factory specification sheet. Durations are the factory's advertised figures at the basis printed on the sheet, not duration at .050" lift; lobe separation is calculated from the printed valve timing.
| Bore/stroke character | 1.052 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,625 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 41.4 ci |
Each link opens the calculator with this engine's specs already filled in.
These records share identical bore, stroke, displacement and compression. They differ by model year and factory power rating.
| Year | Advertised HP | Code |
|---|---|---|
| 1953 | 210 hp | — |
| 1954 | 230 hp | — |
| 1955 | 270 hp | — |
1 factory vehicle, 1953–1955. Each year opens that model's engine table.