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Buick 455ci (1971–1976) specs: 455 ci (7.5L) 8-cylinder, 4.313 x 3.90 in (109.6 x 99.1 mm) bore and stroke, 7.9:1 compression. Rated 205 hp, 1971–1976.
The Buick 455ci (1971–1976) is oversquare — the 4.313" bore exceeds the 3.9" stroke by 10.6% — a layout that favors airflow and RPM over leverage at the crank. The 3.9" stroke puts mean piston speed at 4,000 ft/min around 6,150 RPM, which is where a production bottom end is generally considered at its limit. A rod ratio of 1.694 is in the range most production engines fall in. Each of the 8 cylinders displaces 56.9 ci (932 cc).
7.9:1 is low by modern standards and generally happy on regular pump fuel.
It is one of 4 engines in the Buick 455ci family, all of them 455 ci — the differences between them are in compression, heads and rating, not displacement. 7 factory variants share these dimensions, rated at 205 hp across 1971–1976.
| Displacement | 455 ci / 7.5 L |
|---|---|
| Bore | 4.313" |
| Stroke | 3.9" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 7.9:1 * |
| Rod length | 6.607" |
| Rod ratio | 1.694 |
| Bore/stroke ratio | 1.106 |
* Compression ratio from a single source; not yet cross-verified.
| Fuel type | gas |
|---|---|
| Firing order | 1-8-4-3-6-5-7-2 |
| Advertised HP | 205 hp |
| Years | 1971–1976 |
| Bore/stroke character | 1.106 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,900 ft/min — in the range typical of performance street engines |
| Rod ratio | 1.694 — moderate — the range most production V8s fall in |
| Displacement per cylinder | 56.9 ci |
| Static compression | 7.9:1 — low by modern standards, generally happy on regular pump fuel |
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 |
|---|---|---|
| 1971 | — | — |
| 1972 | — | — |
| 1973 | — | — |
| 1974 | — | — |
| 1975 | — | — |
| 1975 | 205 hp | — |
| 1976 | — | — |
4 factory vehicles, 1971–1976. Each year opens that model's engine table.