No way of knowing, to many variables.
216,000 ml
1 litre = 1000 millilitres so 216 L = 216 000 ml.
5.4L
1 liter = 1000 cubic cm 216 cubic cm = 216/1000 liter = 0.216 liter
216L = 7.63 ft³
No. Liters measure volume and horsepower measures work.
6 HP
6.38 L 1 liter = 33.814 oz 1 oz = 0.02 L
6 HP
Horsepower is not measured in litres. Litres is a measure of engine displacement, not power. Power is roughly proportional to displacement, but also varies with many other factors.
There isn't a direct correspondence between horsepower and displacement. It'll depend on the fuel type, thermal efficiency of the engine, programming (in electronically controlled engines), and other factors.
Liter is a measure of volume; horsepower a unit of power (energy per time unit). You can't convert this directly. If you mean, a motor has so-and-so many liters, in general, more liters means more power - but the volume of the pistons is not the only factor that affects the power.