6.4 liters is 390.6 cubic inches (6,400 cc) by straight math. Makers round, so the engines sold as 6.4 L measure from 388.6 to 392.7 cubic inches.
The most common: 390.4 ci (Ford 390 (FE)); 391.6 ci (Dodge 392); 389.6 ci (American Motors 390); 388.8 ci (Pontiac 389 (Pontiac V8)); 392.7 ci (Chrysler 392); 389.5 ci (Cadillac 390 (390 Series)).
| Engine | Codes | Years | Bore × stroke | Cubic inches | cc | Cylinders |
|---|---|---|---|---|---|---|
| Chrysler 392 | 392 Hemi | 1957–1959 | 4.000" × 3.906" | 392.7 | 6,435 | 8 |
| Pontiac 389 (Pontiac V8) | — | 1959–1966 | 4.062" × 3.750" | 388.8 | 6,371 | 8 |
| Cadillac 390 (390 Series) | — | 1959–1963 | 4.000" × 3.874" | 389.5 | 6,382 | 8 |
| Ford 390 (FE) | 390 V-8, Super 390, FE 390 | 1961–1976 | 4.052" × 3.784" | 390.4 | 6,397 | 8 |
| American Motors 390 | — | 1968–1970 | 4.165" × 3.574" | 389.6 | 6,384 | 8 |
| International 392 | V-392 | 1969–1975 | 4.125" × 3.656" | 390.9 | 6,406 | 8 |
| Ford 389 (6.4 Power Stroke) | — | 2008–2010 | 3.870" × 4.130" | 388.6 | 6,369 | 8 (diesel) |
| Dodge 392 | Hemi 6.4, 392 Hemi | 2011–2026 | 4.091" × 3.724" | 391.6 | 6,417 | 8 |
Cubic inches and cc are worked out from each engine's bore and stroke. Years are the model years of the factory cars on this site that list the engine.
Start with the engine code: on 1981-and-later cars and trucks it is a character of the VIN (the 8th on most American makes), and most blocks carry a code stamp. Each engine's page lists its codes and the cars it came in. See the VIN engine code lists by make.
390.6 cubic inches by straight conversion (1 liter = 61.024 cubic inches). Real 6.4 L engines measure 388.6 to 392.7 cubic inches; the table above lists each one.
6,400 cc by definition. The engines sold as 6.4 L range from 6,369 to 6,435 cc.
Makers name engines by rounded sizes. The real size comes from bore × bore × stroke × 0.7854 × cylinders, so two engines sold as the same size are often a few cubic inches apart.