There's no single answer to "how many liters is a Ford 331". "Ford 331" refers to the cubic inch displacement of an engine, not its volume in liters. To convert cubic inches to liters, you need to use the conversion factor: 1 cubic inch ≈ 0.0163871 liters.
Therefore, a Ford 331 cubic inch engine is approximately 5.42 liters (331 cu in * 0.0163871 liters/cu in ≈ 5.42 liters).
