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Chrysler 392 Hemi specs: 392 ci 8-cylinder, 4.00 x 3.906 in (101.6 x 99.2 mm) bore and stroke. Rated 325-380 hp, 1957–1959. Used in the Chrysler 300.
The Chrysler 392 Hemi is close to square: 4" bore against 3.906" stroke, within 2.4%, which splits the difference between a high-revving layout and a torque layout. The 3.906" stroke puts mean piston speed at 4,000 ft/min around 6,150 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 49.0 ci (803 cc).
It is one of 8 engines in the Chrysler 392ci family, all of them 392 ci — the differences between them are in compression, heads and rating, not displacement. 5 factory variants share these dimensions, rated from 325 to 380 hp across 1957–1959.
| Displacement | 392 ci |
|---|---|
| Bore | 4" |
| Stroke | 3.906" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 9.25–10:1 (published figures vary) |
| Bore/stroke ratio | 1.024 |
| Fuel type | gas |
|---|---|
| Advertised HP | 325–380 hp |
| Years | 1957–1959 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. | Duration int / exh | Valve lift int / exh | LSA |
|---|---|---|---|---|---|---|---|
| 1957 | gross | 325 | — | 9.25:1 | — | — | — |
| 1957 | gross | 375 @ 5200 | — | — | — | 0.444" / 0.435" | — |
| 1958 | gross | 345 @ 4600 | — | 10:1 | — | — | — |
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 | 1.024 — square — bore and stroke are within 5%, a balanced compromise |
|---|---|
| Mean piston speed at 6,000 RPM | 3,906 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 49.0 ci |
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 |
|---|---|---|
| 1957 | 325 hp | 392 Hemi |
| 1957 | 375 hp | 392 Hemi |
| 1958 | 345 hp | 392 Hemi |
| 1958 | 380 hp | 392 Hemi |
| 1959 | — | 392 Hemi |
3 factory vehicles, 1957–1959. Each year opens that model's engine table.