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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, 10:1 compression. Rated 345 hp. Rod ratio and piston speed.
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).
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 57 engines in the LS family, sitting between the 293 ci and 454 ci members. Factory fitments include the Cadillac Escalade, Chevrolet Silverado SS, GMC Sierra Denali.
| Displacement | 364 ci / 6 L |
|---|---|
| Bore | 4" |
| Stroke | 3.622" |
| Cylinders | 8 |
| Compression ratio | 10:1 |
| Bore/stroke ratio | 1.104 |
| Block material | cast iron |
|---|---|
| Head material | aluminum |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 345 hp |
| 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 |
| Static compression | 10:1 — in the range that usually runs on pump premium |
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