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Porsche 911 2.4 specs: 2.3L (142.88 ci) 6-cylinder, 84 x 70.4 mm (3.3071 x 2.7717 in) bore and stroke. Rod ratio and piston speed worked out.
The Porsche 911 2.4 is oversquare — the 3.3071" bore exceeds the 2.7717" stroke by 19.3% — a layout that favors airflow and RPM over leverage at the crank. The 2.7717" stroke does not reach 4,000 ft/min of mean piston speed until about 8,650 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 6 cylinders displaces 23.8 ci (390 cc).
It is one of 15 engines in the 911 family, sitting between the 133.95 ci and 163.9 ci members.
| Displacement | 142.88 ci / 2.3 L |
|---|---|
| Bore | 3.3071" |
| Stroke | 2.7717" |
| Cylinders | 6 |
| Compression ratio | 7.5–8.5:1 (published figures vary) |
| Bore/stroke ratio | 1.193 |
| Fuel type | gas |
|---|
| Bore/stroke character | 1.193 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 2,772 ft/min — conservative for a street engine |
| Displacement per cylinder | 23.8 ci |
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