There is way too many factors, such as:
Color of parts being painted, if your going from a light primer color to black its going to need more coats.
The brand of paint, different brands have different levels of reducers, hardeners etc. EX. some PPG basecoat can be reduced as much as 1:2, meaning you'll need 1 quart of base and 1 quart of reducer.
Are the parts going to be sealed? (will reduce amount of basecoat needed)
I also would recommend going to your local supply store and asking them these questions, they get them all the time.