and the same volume (the cylinder), cold air will have more molecules in the cylinder than hot air, thus more oxygen, thus more power. Intercoolers cool the air so that you can get more molecules into the cylinder at any given pressure. Zarcasm is right, there are temperature advantages to cooler air, but I doubt very much, because the temps we are talking about are all low compared to the heat as the cylinder is firing. The main advantage is more molecules.