In my personal experience the amount of water poured inside the moka pot makes a big difference. The more water you pour in, the higher temperature the coffee b

In my personal experience the amount of water poured inside the moka pot makes a big difference. The more water you pour in, the higher temperature the coffee brews. If you pour the maximum amount of water that fits inside, then your coffee will brew close to the boiling point of water, which is too hot and makes the coffee bitter. If you pour less amount of water, then the coffee brews at a lower temperature. The principle is that the coffee is pushed out by both the steam and the expanding trapped air inside the moka pot. The more expanding trapped air you have there, the less pressure you need from steam, so the coffee starts brewing earlier.