Pie dough is 100% flour, 66% fat, 33% water. Or, in a small batch, 24 oz flour, 16 oz fat, 8 oz water. Tart or short dough is 100% flour, 66% fat, 33% sugar, with some egg if you want. That translates to 24 oz flour, 16 oz butter, 8 oz sugar. I would use 2 eggs in that, plus vanilla and lemon extract. Notice the way in which these doughs are 3 parts to 2 parts to 1 part. Tart dough is short and crumbly because the flour and butter are rubbed together very well. Pie dough is flaky because the fat is left in big pieces. The amount of free flour in the dough determines how much water it will take to make a dough. So what are you looking for? Flaky, or crisp and crumbly?