See other engines in this family
Mercury 351W EFI specs: 351 ci (5.8L) 8-cylinder, 4.00 x 3.50 in (101.6 x 88.9 mm) bore and stroke, 8.8:1 compression. Rated 210 hp. OHV.
The Mercury 351W EFI is oversquare — the 4" bore exceeds the 3.5" stroke by 14.3% — a layout that favors airflow and RPM over leverage at the crank. The 3.5" stroke puts mean piston speed at 4,000 ft/min around 6,850 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 43.9 ci (719 cc).
8.8:1 on iron heads is low by modern standards and generally happy on regular pump fuel.
It is one of 24 engines in the Windsor family, the largest at 351 ci. Factory fitments include the Mercury Grand Marquis.
| Displacement | 351 ci / 5.8 L |
|---|---|
| Bore | 4" |
| Stroke | 3.5" |
| Cylinders | 8 |
| Compression ratio | 8.8:1 |
| Bore/stroke ratio | 1.143 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 210 hp |
| Bore/stroke character | 1.143 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,500 ft/min — conservative for a street engine |
| Displacement per cylinder | 43.9 ci |
| Static compression | 8.8:1 — low by modern standards, generally happy on regular pump fuel |
Each link opens the calculator with this engine's specs already filled in.