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Pontiac LD2 specs: 138 ci (2.3L) 4-cylinder, 3.622 x 3.346 in (92 x 85 mm) bore and stroke. Rated 160 hp, 1990–1991. Used in the Pontiac Grand Prix. DOHC.
The Pontiac 138ci (LD2) is oversquare — the 3.622" bore exceeds the 3.3465" stroke by 8.2% — a layout that favors airflow and RPM over leverage at the crank. The 3.3465" stroke does not reach 4,000 ft/min of mean piston speed until about 7,150 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 4 cylinders displaces 34.5 ci (565 cc).
It is one of 5 engines in the Pontiac 138ci family, all of them 138 ci — the differences between them are in compression, heads and rating, not displacement. 2 factory variants share these dimensions, rated at 160 hp across 1990–1991.
| Displacement | 138 ci / 2.3 L |
|---|---|
| Bore | 3.622" |
| Stroke | 3.3465" |
| Cylinders | 4 |
| Configuration | I4 |
| Bore/stroke ratio | 1.082 |
| Block material | cast iron |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | gas |
| Advertised HP | 160 hp |
| Years | 1990–1991 |
| Bore/stroke character | 1.082 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,347 ft/min — conservative for a street engine |
| Displacement per cylinder | 34.5 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 |
|---|---|---|
| 1990 | 160 hp | LD2 |
| 1991 | 160 hp | LD2 |