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GMC L38 specs: 151 ci (2.5L) 4-cylinder, 4.00 x 3.00 in (101.6 x 76.2 mm) bore and stroke. Rated 105 hp, 1993. Used in the Grumman LLV and GMC S-15 / Sonoma.
The GMC 151ci (L38) is oversquare — the 4" bore exceeds the 3" stroke by 33.3% — a layout that favors airflow and RPM over leverage at the crank. The 3" stroke does not reach 4,000 ft/min of mean piston speed until about 8,000 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 4 cylinders displaces 37.8 ci (619 cc).
It is one of 2 engines in the GMC 151ci family, all of them 151 ci — the differences between them are in compression, heads and rating, not displacement.
| Displacement | 151 ci / 2.5 L |
|---|---|
| Bore | 4" |
| Stroke | 3" |
| Cylinders | 4 |
| Configuration | I4 |
| Bore/stroke ratio | 1.333 |
| Fuel type | gas |
|---|---|
| Advertised HP | 105 hp |
| Years | 1993 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. |
|---|---|---|---|---|
| 1993 | L38 net | 105 @ 4800 | 135 lb-ft @ 3200 | — |
Factory specification sheet.
| Bore/stroke character | 1.333 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,000 ft/min — conservative for a street engine |
| Displacement per cylinder | 37.8 ci |
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3 factory vehicles, 1987–1994. Each year opens that model's engine table.