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Dodge 6.4L Hemi (392 Apache) specs: 392 ci (6.4L) 8-cylinder, 4.091 x 3.724 in (103.9 x 94.6 mm) bore and stroke, 10.9:1 compression. Rated 470 hp. OHV.
The Dodge 6.4L Hemi (392 Apache) is oversquare — the 4.0906" bore exceeds the 3.7244" stroke by 9.8% — a layout that favors airflow and RPM over leverage at the crank. The 3.7244" stroke puts mean piston speed at 4,000 ft/min around 6,450 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 49.0 ci (803 cc).
10.9:1 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 16 engines in the Gen III Hemi family, the largest at 392 ci. Factory fitments include the Dodge Challenger SRT8 392, Dodge Charger SRT8, Chrysler 300 SRT8 and 3 others.
| Displacement | 392 ci / 6.4 L |
|---|---|
| Bore | 4.0906" |
| Stroke | 3.7244" |
| Cylinders | 8 |
| Compression ratio | 10.9:1 |
| Bore/stroke ratio | 1.098 |
| Block material | cast iron |
|---|---|
| Head material | aluminum |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 470 hp |
| Bore/stroke character | 1.098 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,724 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 49.0 ci |
| Static compression | 10.9:1 — in the range that usually runs on pump premium |
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