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GMC LH8 specs: 325 ci (5.3L) 8-cylinder, 3.78 x 3.622 in (96 x 92 mm) bore and stroke. Rated 300 hp, 2009. Used in the Hummer H3 and GMC Canyon. OHV.
The GMC 325ci (LH8) is close to square: 3.7799" bore against 3.622" stroke, within 4.4%, which splits the difference between a high-revving layout and a torque layout. 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 40.6 ci (666 cc).
It is one of 15 engines in the GMC 325ci family, all of them 325 ci — the differences between them are in compression, heads and rating, not displacement.
| Displacement | 325 ci / 5.3 L |
|---|---|
| Bore | 3.7799" |
| Stroke | 3.622" |
| Cylinders | 8 |
| Configuration | V8 |
| Bore/stroke ratio | 1.044 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 300 hp |
| Years | 2009 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. |
|---|---|---|---|---|
| 2009 | LH6 / LH8 net | 300 @ 5200 * | 320 lb-ft @ 4000 * | — |
Factory specification sheet. * Not yet cross-verified.
| Bore/stroke character | 1.044 — square — bore and stroke are within 5%, a balanced compromise |
|---|---|
| Mean piston speed at 6,000 RPM | 3,622 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 40.6 ci |
Each link opens the calculator with this engine's specs already filled in.
3 factory vehicles, 2008–2009. Each year opens that model's engine table.