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GMC LH6 / LL4 specs: 379 ci (6.2L) 8-cylinder, 3.98 x 3.82 in (101.1 x 97 mm) bore and stroke. Built 1983–1993. Used in the Chevrolet C/K Pickup. OHV.
The GMC LH6 / LL4 is close to square: 3.98" bore against 3.82" stroke, within 4.2%, which splits the difference between a high-revving layout and a torque layout. The 3.82" stroke puts mean piston speed at 4,000 ft/min around 6,300 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 47.4 ci (776 cc).
It is one of 2 engines in the GMC 379ci family, all of them 379 ci — the differences between them are in compression, heads and rating, not displacement. 11 factory variants share these dimensions across 1983–1993.
| Displacement | 379 ci / 6.2 L |
|---|---|
| Bore | 3.98" |
| Stroke | 3.82" |
| Cylinders | 8 |
| Configuration | V8 |
| Bore/stroke ratio | 1.042 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | diesel |
| Years | 1983–1993 |
| Bore/stroke character | 1.042 — square — bore and stroke are within 5%, a balanced compromise |
|---|---|
| Mean piston speed at 6,000 RPM | 3,820 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 47.4 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 |
|---|---|---|
| 1983 | — | LH6 / LL4 |
| 1984 | — | LH6 / LL4 |
| 1985 | — | LH6 / LL4 |
| 1986 | — | LH6 / LL4 |
| 1987 | — | LH6 / LL4 |
| 1988 | — | LH6 / LL4 |
| 1989 | — | LH6 / LL4 |
| 1990 | — | LH6 / LL4 |
| 1991 | — | LH6 / LL4 |
| 1992 | — | LH6 / LL4 |
| 1993 | — | LH6 / LL4 |
8 factory vehicles, 1982–1993. Each year opens that model's engine table.