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Pontiac L73 specs: 98 ci (1.6L) 4-cylinder, 3.228 x 2.98 in (82 x 75.7 mm) bore and stroke. Rated 74 hp, 1988–1993. Used in the Pontiac LeMans.
The Pontiac 98ci (L73) is oversquare — the 3.228" bore exceeds the 2.98" stroke by 8.3% — a layout that favors airflow and RPM over leverage at the crank. The 2.98" stroke does not reach 4,000 ft/min of mean piston speed until about 8,050 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. A rod ratio of 1.611 is in the range most production engines fall in. Each of the 4 cylinders displaces 24.5 ci (401 cc).
It is one of 2 engines in the Pontiac 98ci family, all of them 98 ci — the differences between them are in compression, heads and rating, not displacement. 6 factory variants share these dimensions, rated at 74 hp across 1988–1993.
| Displacement | 98 ci / 1.6 L |
|---|---|
| Bore | 3.228" |
| Stroke | 2.98" |
| Cylinders | 4 |
| Configuration | I4 |
| Rod length | 4.8" |
| Rod ratio | 1.611 |
| Bore/stroke ratio | 1.083 |
| Fuel type | gas |
|---|---|
| Advertised HP | 74 hp |
| Years | 1988–1993 |
| Bore/stroke character | 1.083 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 2,980 ft/min — conservative for a street engine |
| Rod ratio | 1.611 — moderate — the range most production V8s fall in |
| Displacement per cylinder | 24.5 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 |
|---|---|---|
| 1988 | 74 hp | L73 |
| 1989 | 74 hp | L73 |
| 1990 | 74 hp | L73 |
| 1991 | 74 hp | L73 |
| 1992 | 74 hp | L73 |
| 1993 | 74 hp | L73 |