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Ram Magnum 3.9 specs: 239 ci (3.9L) 6-cylinder, 3.909 x 3.311 in (99.3 x 84.1 mm) bore and stroke. Rated 175-180 hp, 1992–2003.
The Ram Magnum 3.9 is oversquare — the 3.9094" bore exceeds the 3.311" stroke by 18.1% — a layout that favors airflow and RPM over leverage at the crank. The 3.311" stroke does not reach 4,000 ft/min of mean piston speed until about 7,250 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 6 cylinders displaces 39.8 ci (653 cc).
It is one of 13 engines in the Magnum family, sitting between the 226 ci and 488 ci members. 12 factory variants share these dimensions, rated from 175 to 180 hp across 1992–2003.
| Displacement | 239 ci / 3.9 L |
|---|---|
| Bore | 3.9094" |
| Stroke | 3.311" |
| Cylinders | 6 |
| Configuration | V6 |
| Bore/stroke ratio | 1.181 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 175–180 hp |
| Years | 1992–2003 |
| Bore/stroke character | 1.181 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,311 ft/min — conservative for a street engine |
| Displacement per cylinder | 39.8 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 |
|---|---|---|
| 1992 | 180 hp | Magnum 3.9 |
| 1993 | 180 hp | Magnum 3.9 |
| 1994 | 175 hp | Magnum 3.9 |
| 1995 | 175 hp | Magnum 3.9 |
| 1996 | 175 hp | Magnum 3.9 |
| 1997 | 175 hp | Magnum 3.9 |
| 1998 | 175 hp | Magnum 3.9 |
| 1999 | 175 hp | Magnum 3.9 |
| 2000 | 175 hp | Magnum 3.9 |
| 2001 | 175 hp | Magnum 3.9 |
| 2002 | 175 hp | Magnum 3.9 |
| 2003 | 175 hp | Magnum 3.9 |