First of all, as kg is a mass measurement and liter a volume measurement, there can be no straight conversion factor as various materials have differing densities.
You would need to know the density of the material. The specific gravity is a ratio which compares the density of any material with that of water. Water is given the s.g. of 1.00 so that a piece of lead would have an s.g. of greater than 1.00 and most woods an s.g. of less than 1.00
One constant is that of liquid water where 1kg = 1 liter so if that's your problem, then it is a straight 1:1 conversion. Hence 1.13 kg = 1.13 liters.