Originally Posted by TitaniumStick
I will grant you that for a steady state, (typically)forced induction application, preheating the fuel/air via waste heat is an effective way to increase overall process efficiency. I can't think of any naturally aspirated, reciprocating combustion applications where that holds true. A motor vehicle engine is much too transitional for that type of process efficiency to be applied. IMHO, the loss in performance due to the timing pulled for knock prevention will more then offset any efficiency gained in leaning the fuel to account for the lower air density.
Good discussion! Keep 'em coming!
^^this, it's why they make 'cold air' intakes. I pulled the cover for one day last week (was 88 out), the heat soak dragged my perfomance to a standstill. Maybe in the winter or spring/fall, but I don't recommend it for the summer. It's basically a short ram with no heat sheild.