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Chevrolet LQ9 specs: 364 ci (6.0L) 8-cylinder, 4.00 x 3.622 in (101.6 x 92 mm) bore and stroke. Rated 345 hp, 2003–2007. Used in the Chevrolet Silverado 1500.
The Chevrolet LS (LQ9) is oversquare — the 4" bore exceeds the 3.622" stroke by 10.4% — 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. Each of the 8 cylinders displaces 45.5 ci (746 cc).
It is one of 57 engines in the LS family, sitting between the 293 ci and 454 ci members. 5 factory variants share these dimensions, rated at 345 hp across 2003–2007.
| Displacement | 364 ci / 6 L |
|---|---|
| Bore | 4" |
| Stroke | 3.622" |
| Cylinders | 8 |
| Configuration | V8 |
| Bore/stroke ratio | 1.104 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 345 hp |
| Years | 2003–2007 |
| Bore/stroke character | 1.104 — 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 |
| Displacement per cylinder | 45.5 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 |
|---|---|---|
| 2003 | 345 hp | LQ9 |
| 2004 | 345 hp | LQ9 |
| 2005 | 345 hp | LQ9 |
| 2006 | 345 hp | LQ9 |
| 2007 | 345 hp | LQ9 |