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Alfa Romeo 115.41 specs: 120 ci 4-cylinder, 84 x 88.5 mm (3.3071 x 3.4843 in) bore and stroke, 9:1 compression. Built 1971–1981.
The Alfa Romeo 115.41 is undersquare — the 3.4843" stroke exceeds the 3.3071" bore by 5.1% — a layout that trades peak RPM for leverage and torque low in the range. The 3.4843" stroke puts mean piston speed at 4,000 ft/min around 6,900 RPM, which is where a production bottom end is generally considered at its limit. Each of the 4 cylinders displaces 30.0 ci (492 cc).
9:1 is low by modern standards and generally happy on regular pump fuel.
It is one of 3 engines in the Alfa Romeo 120ci family, all of them 120 ci — the differences between them are in compression, heads and rating, not displacement. 11 factory variants share these dimensions across 1971–1981.
| Displacement | 120 ci |
|---|---|
| Bore | 3.3071" |
| Stroke | 3.4843" |
| Cylinders | 4 |
| Configuration | I4 |
| Compression ratio | 9:1 |
| Bore/stroke ratio | 0.949 |
| Fuel type | gas |
|---|---|
| Years | 1971–1981 |
| Bore/stroke character | 0.949 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 3,484 ft/min — conservative for a street engine |
| Displacement per cylinder | 30.0 ci |
| Static compression | 9:1 — 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 |
|---|---|---|
| 1971 | — | 115.41 |
| 1972 | — | 115.41 |
| 1973 | — | 115.41 |
| 1974 | — | 115.41 |
| 1975 | — | 115.41 |
| 1976 | — | 115.41 |
| 1977 | — | 115.41 |
| 1978 | — | 115.41 |
| 1979 | — | 115.41 |
| 1980 | — | 115.41 |
| 1981 | — | 115.41 |
1 factory vehicle, 1971–1981. Each year opens that model's engine table.