I really should know better . . . but, when you buy sand or gravel at a lumber yard or a home improvement store, they are sold by the cubic yard. Do you consider sand or gravel to be liquids?
So let's examine your foolishness since you began posting here:
It looks like about 8oz in 2 cups.
2 cups = .47 litres
That means about 17 oz in a litre.
A cup is
eight ounces, so it cannot be that eight ounces is two cups. Also, you write "about 17 oz in a litre," which seems to suggest that you're talking about measures of volume (a cup is a measure of volume, not of weight). There are 33.8+ ounces in a liter, not 17. If you meant weight rather than volume, tell me which weighs more, a liter of water or a liter of oil-based paint? In fact, a liter in the old metric system is defined as the volume occupied by one thousand grams of water.
Furthermore, the OP is asking for a volume to weight conversion. Therefore, you cannot use a cup for an approximation of that conversion, as a cup is a measure of volume, not of weight.
Come on, Parados, this ain't rocket science.