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Ram 400 B V8 specs: 400 ci (6.6L) 8-cylinder, 4.339 x 3.374 in (110.2 x 85.7 mm) bore and stroke, 8.2:1 compression. Rated 200 hp. Rod ratio and piston speed.
The Ram 400 B V8 is oversquare — the 4.3386" bore exceeds the 3.374" stroke by 28.6% — a layout that favors airflow and RPM over leverage at the crank. The 3.374" stroke does not reach 4,000 ft/min of mean piston speed until about 7,100 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 8 cylinders displaces 50.0 ci (819 cc).
8.2:1 on iron heads is low by modern standards and generally happy on regular pump fuel.
It is one of 3 engines in the B family, the largest at 400 ci. Factory fitments include the Dodge D-Series, Dodge Ramcharger.
| Displacement | 400 ci / 6.6 L |
|---|---|
| Bore | 4.3386" |
| Stroke | 3.374" |
| Cylinders | 8 |
| Compression ratio | 8.2:1 |
| Bore/stroke ratio | 1.286 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 200 hp |
| Bore/stroke character | 1.286 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,374 ft/min — conservative for a street engine |
| Displacement per cylinder | 50.0 ci |
| Static compression | 8.2:1 — low by modern standards, generally happy on regular pump fuel |
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