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The same engine also has a main page: Plymouth A588.
Plymouth 20 Neon I4 specs: 122 ci (2.0L) 4-cylinder, 3.445 x 3.268 in (87.5 x 83 mm) bore and stroke, 9.8:1 compression. Rated 132 hp. SOHC.
The Plymouth 20 Neon I4 is oversquare — the 3.4449" bore exceeds the 3.2677" stroke by 5.4% — a layout that favors airflow and RPM over leverage at the crank. The 3.2677" stroke does not reach 4,000 ft/min of mean piston speed until about 7,350 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 4 cylinders displaces 30.5 ci (500 cc).
9.8:1 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.
Factory fitments include the Neon, Breeze, Plymouth Breeze and 1 other.
| Displacement | 122 ci / 2 L |
|---|---|
| Bore | 3.4449" |
| Stroke | 3.2677" |
| Cylinders | 4 |
| Compression ratio | 9.8:1 |
| Bore/stroke ratio | 1.054 |
| Block material | cast iron |
|---|---|
| Head material | aluminum |
| Valvetrain | SOHC |
| Fuel type | gas |
| Advertised HP | 132 hp |
| Bore/stroke character | 1.054 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,268 ft/min — conservative for a street engine |
| Displacement per cylinder | 30.5 ci |
| Static compression | 9.8:1 — in the range that usually runs on pump premium |
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