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Pontiac LA5 specs: 110 ci (1.8L) 4-cylinder, 3.339 x 3.13 in (84.8 x 79.5 mm) bore and stroke, 8:1 compression. Rated 150 hp, 1984–1986.
The Pontiac 110ci (LA5) is oversquare — the 3.3386" bore exceeds the 3.1299" stroke by 6.7% — a layout that favors airflow and RPM over leverage at the crank. The 3.1299" stroke does not reach 4,000 ft/min of mean piston speed until about 7,650 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 4 cylinders displaces 27.5 ci (451 cc).
8:1 is low by modern standards and generally happy on regular pump fuel.
It is one of 2 engines in the Pontiac 110ci family, all of them 110 ci — the differences between them are in compression, heads and rating, not displacement. 3 factory variants share these dimensions, rated at 150 hp across 1984–1986.
| Displacement | 110 ci / 1.8 L |
|---|---|
| Bore | 3.3386" |
| Stroke | 3.1299" |
| Cylinders | 4 |
| Configuration | I4 |
| Compression ratio | 8:1 |
| Bore/stroke ratio | 1.067 |
| Fuel type | gas |
|---|---|
| Advertised HP | 150 hp |
| Years | 1984–1986 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. |
|---|---|---|---|---|
| 1984 | LA5 net | 150 @ 5600 | 150 lb-ft @ 2800 | 8:1 |
| 1985 | LA5 net | 150 @ 5600 | 150 lb-ft @ 2800 | 8:1 |
| 1986 | LA5 net | 150 @ 5600 | 150 lb-ft @ 2800 | 8:1 |
Factory specification sheet.
| Bore/stroke character | 1.067 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,130 ft/min — conservative for a street engine |
| Displacement per cylinder | 27.5 ci |
| Static compression | 8:1 — low by modern standards, generally happy on regular pump fuel |
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 |
|---|---|---|
| 1984 | 150 hp | LA5 |
| 1985 | 150 hp | LA5 |
| 1986 | 150 hp | LA5 |
1 factory vehicle, 1984–1986. Each year opens that model's engine table.