They are engine sizes listed by companies. The problem is you can't do direct conversions a lot of the time. Companies used to use cubic inches for engine displacement, then changed to Liters, however in order to keep the common sizes used they had to give it a value in L, even if it was off by a tad. For example the main Ford V-8 engine pre-1970 was a 289ci motor, after they changed to L the 289 was called the 4.7, even though 4.7 really means 287ci.
Believe it or not quite a lot of those numbers were from memory, the smaller ones I knew from being common car/truck engine sizes, the larger ones are common diesel sizes. For example the 9.6L 585 was a Moline tractor diesel and the 8.5 (519) is a commonly used Cat diesel.
