# The effect of the size of the intake manifold on a forced induction engine?

Theoretically speaking, a smaller intake manifold would mean higher pressure, which would then cause the air to enter the cylinders more "aggressively" at lower engine speeds but cause more resistance at higher engine speeds. And then a larger intake manifold would have a lower pressure in it so it would... show more Theoretically speaking, a smaller intake manifold would mean higher pressure, which would then cause the air to enter the cylinders more "aggressively" at lower engine speeds but cause more resistance at higher engine speeds. And then a larger intake manifold would have a lower pressure in it so it would rely more on the vacuum created by the cylinders going down at low engine speeds but would have very low resistance at high engine speeds.

But how true is this?
Update: For example: say our turbo moves 33 liters of air per second. In intake manifold 1 with an internal volume of 1 liter, and an intake manifold 2 with an internal volume of 2 liters, intake manifold 1 will have a pressure of around 34+ atm (absolute pressure), while intake manifold 2 will have 17.5+ atm (absolute... show more For example: say our turbo moves 33 liters of air per second. In intake manifold 1 with an internal volume of 1 liter, and an intake manifold 2 with an internal volume of 2 liters, intake manifold 1 will have a pressure of around 34+ atm (absolute pressure), while intake manifold 2 will have 17.5+ atm (absolute pressure), meaning that at the same engine speed, the same engine with the smaller intake manifold has twice as much pressure inside which should technically push more air inside.