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Chevrolet RPO 300 specs: 327 ci (5.4L) 8-cylinder, 4.001 x 3.25 in (101.6 x 82.6 mm) bore and stroke. Rated 250 hp, 1962. Used in the Chevrolet Bel Air.
The Chevrolet RPO 300 is oversquare — the 4.001" bore exceeds the 3.25" stroke by 23.1% — a layout that favors airflow and RPM over leverage at the crank. The 3.25" stroke does not reach 4,000 ft/min of mean piston speed until about 7,400 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. A rod ratio of 1.754 is long by production standards — less side-load on the cylinder wall and gentler piston acceleration around TDC, the geometry that tolerates high RPM. Each of the 8 cylinders displaces 40.9 ci (670 cc).
It is one of 20 engines in the Chevrolet 327ci family, all of them 327 ci — the differences between them are in compression, heads and rating, not displacement.
| Displacement | 327 ci / 5.4 L |
|---|---|
| Bore | 4.001" |
| Stroke | 3.25" |
| Cylinders | 8 |
| Configuration | V8 |
| Rod length | 5.7" |
| Rod ratio | 1.754 |
| Bore/stroke ratio | 1.231 |
| Fuel type | gas |
|---|---|
| Advertised HP | 250 hp |
| Years | 1962 |
| Bore/stroke character | 1.231 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,250 ft/min — conservative for a street engine |
| Rod ratio | 1.754 — long — less side loading on the cylinder wall, favours high RPM |
| Displacement per cylinder | 40.9 ci |
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