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Cadillac L31 specs: 350 ci (5.7L) 8-cylinder, 4.00 x 3.48 in (101.6 x 88.4 mm) bore and stroke, 9.4:1 compression. Rated 255 hp, 1999–2000.
The Cadillac 350ci (L31) is oversquare — the 4" bore exceeds the 3.48" stroke by 14.9% — a layout that favors airflow and RPM over leverage at the crank. The 3.48" stroke puts mean piston speed at 4,000 ft/min around 6,900 RPM, which is where a production bottom end is generally considered at its limit. A rod ratio of 1.638 is in the range most production engines fall in. Each of the 8 cylinders displaces 43.8 ci (717 cc).
9.4:1 is low by modern standards and generally happy on regular pump fuel.
It is one of 4 engines in the Cadillac 350ci family, all of them 350 ci — the differences between them are in compression, heads and rating, not displacement. 2 factory variants share these dimensions, rated at 255 hp across 1999–2000.
| Displacement | 350 ci / 5.7 L |
|---|---|
| Bore | 4" |
| Stroke | 3.48" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 9.4:1 |
| Rod length | 5.7" |
| Rod ratio | 1.638 |
| Bore/stroke ratio | 1.149 |
| Deck height | 9.025" |
| Fuel type | gas |
|---|---|
| Advertised HP | 255 hp |
| Years | 1999–2000 |
| Engine weight | 575 lb (approximate; published figures vary with what is attached) |
| Bore/stroke character | 1.149 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,480 ft/min — conservative for a street engine |
| Rod ratio | 1.638 — moderate — the range most production V8s fall in |
| Displacement per cylinder | 43.8 ci |
| Static compression | 9.4:1 — 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 |
|---|---|---|
| 1999 | 255 hp | L31 |
| 2000 | 255 hp | L31 |
9 factory vehicles, 1996–2002. Each year opens that model's engine table.