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Mercury 368ci (1957) specs: 368 ci 8-cylinder, 4.00 x 3.66 in (101.6 x 93 mm) bore and stroke, 9.75:1 compression. Rated 290 hp, 1957.
The Mercury 368ci (1957) is oversquare — the 4" bore exceeds the 3.66" stroke by 9.3% — a layout that favors airflow and RPM over leverage at the crank. The 3.66" stroke puts mean piston speed at 4,000 ft/min around 6,550 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 46.0 ci (754 cc).
9.75:1 is in the range that usually runs on pump premium.
| Displacement | 368 ci |
|---|---|
| Bore | 4" |
| Stroke | 3.66" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 9.75:1 |
| Bore/stroke ratio | 1.093 |
| Fuel type | gas |
|---|---|
| Advertised HP | 290 hp |
| Years | 1957 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. |
|---|---|---|---|---|
| 1957 | gross | 290 | — | 9.75:1 |
Factory specification sheet.
| Bore/stroke character | 1.093 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,660 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 46.0 ci |
| Static compression | 9.75:1 — in the range that usually runs on pump premium |
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2 factory vehicles, 1957. Each year opens that model's engine table.