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Ford Essex 3.9 specs: 239 ci (3.9L) 6-cylinder, 3.811 x 3.465 in (96.8 x 88 mm) bore and stroke. Rated 193 hp, 2004–2007. Used in the Ford Freestar.
The Ford Essex 3.9 is oversquare — the 3.811" bore exceeds the 3.4646" stroke by 10.0% — a layout that favors airflow and RPM over leverage at the crank. The 3.4646" stroke puts mean piston speed at 4,000 ft/min around 6,950 RPM, which is where a production bottom end is generally considered at its limit. Each of the 6 cylinders displaces 39.8 ci (653 cc).
It is one of 2 engines in the Ford 239ci family, all of them 239 ci — the differences between them are in compression, heads and rating, not displacement. 4 factory variants share these dimensions, rated at 193 hp across 2004–2007.
| Displacement | 239 ci / 3.9 L |
|---|---|
| Bore | 3.811" |
| Stroke | 3.4646" |
| Cylinders | 6 |
| Configuration | V6 |
| Bore/stroke ratio | 1.1 |
| Fuel type | gas |
|---|---|
| Advertised HP | 193 hp |
| Years | 2004–2007 |
| Bore/stroke character | 1.100 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,465 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 |
|---|---|---|
| 2004 | 193 hp | Essex 3.9 |
| 2005 | 193 hp | Essex 3.9 |
| 2006 | 193 hp | Essex 3.9 |
| 2007 | 193 hp | Essex 3.9 |
1 factory vehicle, 2004–2007. Each year opens that model's engine table.