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Chevrolet RPO 580 specs: 409 ci (6.7L) 8-cylinder, 4.313 x 3.50 in (109.6 x 88.9 mm) bore and stroke. Rated 360-380 hp, 1961–1962.
The Chevrolet RPO 580 is oversquare — the 4.313" bore exceeds the 3.5" stroke by 23.2% — a layout that favors airflow and RPM over leverage at the crank. The 3.5" stroke puts mean piston speed at 4,000 ft/min around 6,850 RPM, which is where a production bottom end is generally considered at its limit. A rod ratio of 1.717 is in the range most production engines fall in. Each of the 8 cylinders displaces 51.1 ci (838 cc).
It is one of 7 engines in the Chevrolet 409ci family, all of them 409 ci — the differences between them are in compression, heads and rating, not displacement. 2 factory variants share these dimensions, rated from 360 to 380 hp across 1961–1962.
| Displacement | 409 ci / 6.7 L |
|---|---|
| Bore | 4.313" |
| Stroke | 3.5" |
| Cylinders | 8 |
| Configuration | V8 |
| Rod length | 6.01" |
| Rod ratio | 1.717 |
| Bore/stroke ratio | 1.232 |
| Fuel type | gas |
|---|---|
| Advertised HP | 360–380 hp |
| Years | 1961–1962 |
| Bore/stroke character | 1.232 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,500 ft/min — conservative for a street engine |
| Rod ratio | 1.717 — moderate — the range most production V8s fall in |
| Displacement per cylinder | 51.1 ci |
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These records share identical bore, stroke, displacement and compression. They differ by model year and factory power rating.
| Year | Advertised HP | Code |
|---|---|---|
| 1961 | 360 hp | RPO 580 |
| 1962 | 380 hp | RPO 580 |