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Cadillac LS6 specs: 346 ci (5.7L) 8-cylinder, 3.90 x 3.622 in (99.1 x 92 mm) bore and stroke, 10.5:1 compression. Rated 400 hp, 2004–2005.
The Cadillac 346ci (LS6) is oversquare — the 3.9" bore exceeds the 3.622" stroke by 7.7% — a layout that favors airflow and RPM over leverage at the crank. The 3.622" stroke puts mean piston speed at 4,000 ft/min around 6,650 RPM, which is where a production bottom end is generally considered at its limit. A rod ratio of 1.684 is in the range most production engines fall in. Each of the 8 cylinders displaces 43.3 ci (709 cc).
10.5:1 on aluminum heads is in the range that usually runs on pump premium; aluminum sheds heat faster than iron, which makes the same number a little more forgiving.
2 factory variants share these dimensions, rated at 400 hp across 2004–2005.
| Displacement | 346 ci / 5.7 L |
|---|---|
| Bore | 3.9" |
| Stroke | 3.622" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 10.5:1 |
| Rod length | 6.098" |
| Rod ratio | 1.684 |
| Bore/stroke ratio | 1.077 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 400 hp |
| Years | 2004–2005 |
| Bore/stroke character | 1.077 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,622 ft/min — in the range typical of performance street engines |
| Rod ratio | 1.684 — moderate — the range most production V8s fall in |
| Displacement per cylinder | 43.3 ci |
| Static compression | 10.5:1 — in the range that usually runs on pump premium |
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 |
|---|---|---|
| 2004 | 400 hp | LS6 |
| 2005 | 400 hp | LS6 |
2 factory vehicles, 2001–2005. Each year opens that model's engine table.