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Jeep 401 specs: 401 ci (6.6L) 8-cylinder, 4.165 x 3.68 in (105.8 x 93.5 mm) bore and stroke, 8.25:1 compression. Rated 215 hp. Rod ratio and piston speed.
The Jeep AMC V8 (401) is oversquare — the 4.165" bore exceeds the 3.68" stroke by 13.2% — a layout that favors airflow and RPM over leverage at the crank. The 3.68" stroke puts mean piston speed at 4,000 ft/min around 6,500 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 50.1 ci (821 cc).
8.25:1 on iron heads is low by modern standards and generally happy on regular pump fuel.
It is one of 7 engines in the AMC V8 family, the largest at 401 ci. 2 factory variants share these dimensions, rated at 215 hp. Factory fitments include the Jeep J-Series Truck, Jeep Wagoneer SJ, Jeep Cherokee SJ and 10 others.
| Displacement | 401 ci / 6.6 L |
|---|---|
| Bore | 4.165" |
| Stroke | 3.68" |
| Cylinders | 8 |
| Compression ratio | 8.25:1 |
| Bore/stroke ratio | 1.132 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 215 hp |
| Bore/stroke character | 1.132 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,680 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 50.1 ci |
| Static compression | 8.25:1 — low by modern standards, generally happy on regular pump fuel |
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 |
|---|---|---|
| — | 215 hp | 401 |
| — | 215 hp | 401 |