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Porsche 20 9A2 718 specs: 2.0L (121.3 ci) 4-cylinder, 91 x 76.4 mm (3.5827 x 3.0079 in) bore and stroke, 9.5:1 compression. Rated 300 hp. DOHC.
The Porsche 20 9A2 718 is oversquare — the 3.5827" bore exceeds the 3.0079" stroke by 19.1% — a layout that favors airflow and RPM over leverage at the crank. The 3.0079" stroke does not reach 4,000 ft/min of mean piston speed until about 8,000 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 4 cylinders displaces 30.3 ci (497 cc).
9.5:1 on aluminum heads is in the range that usually runs on pump premium; aluminum sheds heat faster than iron, which makes the same number a little more forgiving.
It is one of 2 engines in the 9A2 Evo family, the smallest at 121.3 ci. Factory fitments include the 718 Boxster, 718 Cayman.
| Displacement | 121.3 ci / 2 L |
|---|---|
| Bore | 3.5827" |
| Stroke | 3.0079" |
| Cylinders | 4 |
| Compression ratio | 9.5:1 |
| Bore/stroke ratio | 1.191 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | gas |
| Advertised HP | 300 hp |
| Bore/stroke character | 1.191 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,008 ft/min — conservative for a street engine |
| Displacement per cylinder | 30.3 ci |
| Static compression | 9.5:1 — in the range that usually runs on pump premium |
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