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Chevrolet RPO 649 specs: 145 ci (2.4L) 6-cylinder, 3.438 x 2.60 in (87.3 x 66 mm) bore and stroke, 9:1 compression. Rated 98-102 hp, 1961–1963.
The Chevrolet RPO 649 is oversquare — the 3.438" bore exceeds the 2.6" stroke by 32.2% — a layout that favors airflow and RPM over leverage at the crank. The 2.6" stroke does not reach 4,000 ft/min of mean piston speed until about 9,250 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. A rod ratio of 1.815 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 6 cylinders displaces 24.2 ci (396 cc).
9:1 is low by modern standards and generally happy on regular pump fuel.
It is one of 5 engines in the Chevrolet 145ci family, all of them 145 ci — the differences between them are in compression, heads and rating, not displacement. 3 factory variants share these dimensions, rated from 98 to 102 hp across 1961–1963.
| Displacement | 145 ci / 2.4 L |
|---|---|
| Bore | 3.438" |
| Stroke | 2.6" |
| Cylinders | 6 |
| Compression ratio | 9:1 |
| Rod length | 4.72" |
| Rod ratio | 1.815 |
| Bore/stroke ratio | 1.322 |
| Fuel type | gas |
|---|---|
| Advertised HP | 98–102 hp |
| Years | 1961–1963 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. | Duration int / exh | Valve lift int / exh | LSA |
|---|---|---|---|---|---|---|---|
| 1961 | gross | 98 @ 4600 | 132 lb-ft @ 2800-3000 | 9:1 | 352° | 0.380" | 108° |
| 1962 | gross | 102 @ 4400 | 134 lb-ft @ 2800-3000 | 9:1 | 352° | 0.380" | 108° |
| 1963 | L62 gross | 102 @ 4400 | 134 lb-ft @ 2800-3000 | 9:1 | 352° / 353° | 0.378" | 110.25° |
Factory specification sheet. Durations are the factory's advertised figures at the basis printed on the sheet, not duration at .050" lift; lobe separation is calculated from the printed valve timing.
| Bore/stroke character | 1.322 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 2,600 ft/min — conservative for a street engine |
| Rod ratio | 1.815 — long — less side loading on the cylinder wall, favours high RPM |
| Displacement per cylinder | 24.2 ci |
| Static compression | 9:1 — low by modern standards, generally happy on regular pump fuel |
Each link opens the calculator with this engine's specs already filled in.
These records share identical bore, stroke, displacement and compression. They differ by model year and factory power rating.
| Year | Advertised HP | Code |
|---|---|---|
| 1961 | 98 hp | RPO 649 |
| 1962 | 102 hp | RPO 649 |
| 1963 | 102 hp | RPO 649 |
1 factory vehicle, 1961–1963. Each year opens that model's engine table.