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Cadillac LQ9 specs: 364 ci (6.0L) 8-cylinder, 4.00 x 3.622 in (101.6 x 92 mm) bore and stroke, 10:1 compression. Rated 345 hp, 2002–2006.
The Cadillac 364ci (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. A rod ratio of 1.684 is in the range most production engines fall in. Each of the 8 cylinders displaces 45.5 ci (746 cc).
10:1 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.
It is one of 4 engines in the Cadillac 364ci family, all of them 364 ci — the differences between them are in compression, heads and rating, not displacement. 5 factory variants share these dimensions, rated at 345 hp across 2002–2006.
| Displacement | 364 ci / 6 L |
|---|---|
| Bore | 4" |
| Stroke | 3.622" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 10:1 * |
| Rod length | 6.098" |
| Rod ratio | 1.684 |
| Bore/stroke ratio | 1.104 |
| Deck height | 9.24" |
* Compression ratio from a single source; not yet cross-verified.
| Block material | cast iron |
|---|---|
| Head material | aluminum |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 345 hp |
| Years | 2002–2006 |
| Engine weight | 540 lb (approximate; published figures vary with what is attached) |
| Piston-to-wall clearance (factory service manual spec, 2003 GM truck LQ9 production (negative = interference; coated skirt)) | -0.0009–0.0012" |
|---|---|
| Ring end gap (factory service manual spec, 2003 GM truck LQ4 and LQ9, production (service: 0.0122-0.023 / 0.020-0.033 / 0.0122-0.037)) | top 0.012–0.020", second 0.020–0.030", oil 0.012–0.034" |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. |
|---|---|---|---|---|
| 2004 | LQ9 net | 345 * | 380 lb-ft * | — |
Factory specification sheet. * Not yet cross-verified.
| 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 |
| Rod ratio | 1.684 — moderate — the range most production V8s fall in |
| Displacement per cylinder | 45.5 ci |
| Static compression | 10:1 — 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 |
|---|---|---|
| 2002 | 345 hp | LQ9 |
| 2003 | 345 hp | LQ9 |
| 2004 | 345 hp | LQ9 |
| 2005 | 345 hp | LQ9 |
| 2006 | 345 hp | LQ9 |
3 factory vehicles, 2002–2007. Each year opens that model's engine table.