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Cadillac LT8/L8B specs: 250 ci (4.1L) 8-cylinder, 3.465 x 3.307 in (88 x 84 mm) bore and stroke. Built 1986–1987. Used in the Cadillac DeVille. OHV.
The Cadillac LT8/L8B is close to square: 3.4646" bore against 3.3071" stroke, within 4.8%, which splits the difference between a high-revving layout and a torque layout. The 3.3071" stroke does not reach 4,000 ft/min of mean piston speed until about 7,250 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 8 cylinders displaces 31.3 ci (512 cc).
It is one of 8 engines in the HT4100 family, the smallest at 250 ci. 2 factory variants share these dimensions across 1986–1987.
| Displacement | 250 ci / 4.1 L |
|---|---|
| Bore | 3.4646" |
| Stroke | 3.3071" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 8.5–9:1 (published figures vary) |
| Bore/stroke ratio | 1.048 |
| Block material | aluminum |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Years | 1986–1987 |
| Bore/stroke character | 1.048 — square — bore and stroke are within 5%, a balanced compromise |
|---|---|
| Mean piston speed at 6,000 RPM | 3,307 ft/min — conservative for a street engine |
| Displacement per cylinder | 31.3 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 |
|---|---|---|
| 1986 | — | LT8/L8B |
| 1987 | — | LT8/L8B |
3 factory vehicles, 1982–1987. Each year opens that model's engine table.