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Buick 181ci (1984–1985) specs: 181 ci (3.0L) 6-cylinder, 3.80 x 2.66 in (96.5 x 67.6 mm) bore and stroke, 9:1 compression. Built 1984–1985.
The Buick 181ci (1984–1985) is oversquare — the 3.8" bore exceeds the 2.66" stroke by 42.9% — a layout that favors airflow and RPM over leverage at the crank. The 2.66" stroke does not reach 4,000 ft/min of mean piston speed until about 9,000 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 6 cylinders displaces 30.2 ci (494 cc).
9:1 is low by modern standards and generally happy on regular pump fuel.
It is one of 3 engines in the Buick 181ci family, all of them 181 ci — the differences between them are in compression, heads and rating, not displacement. 2 factory variants share these dimensions across 1984–1985.
| Displacement | 181 ci / 3 L |
|---|---|
| Bore | 3.8" |
| Stroke | 2.66" |
| Cylinders | 6 |
| Configuration | V6 |
| Compression ratio | 9:1 * |
| Bore/stroke ratio | 1.429 |
* Compression ratio from a single source; not yet cross-verified.
| Fuel type | gas |
|---|---|
| Firing order | 1-6-5-4-3-2 |
| Years | 1984–1985 |
| Bore/stroke character | 1.429 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 2,660 ft/min — conservative for a street engine |
| Displacement per cylinder | 30.2 ci |
| Static compression | 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 |
|---|---|---|
| 1984 | — | — |
| 1985 | — | — |
1 factory vehicle, 1984. Each year opens that model's engine table.