Quote Originally Posted by acannell View Post
The same way that engine wear effects mileage. You have to push the gas pedal harder to get the same speed. Inefficiency. So the idea being tossed around is that a bigger TB hurts atomization and therefore power. So more gas pedal would fix that. And therefore worse mileage. Thats the theory anyway.
Wrong concept.

The larger TB hurts the velocity of the air passing through it if not the optimum size.

Think of water in a pipe. A large pipe that steps down size will INCREASE the pressure at the transition while a smaller pipe opening into a larger area will drop pressure.