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Mercury 3.7L Duratec specs: 227 ci (3.7L) 6-cylinder, 3.76 x 3.413 in (95.5 x 86.7 mm) bore and stroke, 10.3:1 compression. Rated 270-273 hp. DOHC.
The Mercury 3.7L Duratec is oversquare — the 3.7598" bore exceeds the 3.4134" stroke by 10.1% — a layout that favors airflow and RPM over leverage at the crank. The 3.4134" stroke does not reach 4,000 ft/min of mean piston speed until about 7,050 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 6 cylinders displaces 37.8 ci (620 cc).
10.3:1 on aluminum heads is in the range that usually runs on pump premium; aluminum sheds heat faster than iron, which makes the same number a little more forgiving.
It is one of 12 engines in the Duratec family, the largest at 227 ci. 2 factory variants share these dimensions, rated from 270 to 273 hp. Factory fitments include the Mercury Milan, Mercury Mountaineer.
| Displacement | 227 ci / 3.7 L |
|---|---|
| Bore | 3.7598" |
| Stroke | 3.4134" |
| Cylinders | 6 |
| Compression ratio | 10.3:1 |
| Bore/stroke ratio | 1.101 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | gas |
| Advertised HP | 270–273 hp |
| Bore/stroke character | 1.101 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,413 ft/min — conservative for a street engine |
| Displacement per cylinder | 37.8 ci |
| Static compression | 10.3:1 — in the range that usually runs on pump premium |
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 |
|---|---|---|
| — | 270 hp | Duratec 37, 3.7L Duratec |
| — | 273 hp | 3.7L, 3.7L Duratec |