In the port injection arrangement, the injector is
placed on the side of the intake manifold. The
injector sprays petrol into the air inside the intake
manifold. The petrol mixes with the air completely.
This mixture of petrol and air then passes through the
intake valve and enters into the cylinders.
Port fuel injection (PFI), systems use one injector at
each cylinder. They are mounted in the intake
manifold near the cylinder head where they can inject
a fine, atomized fuel, mist as closed as possible to the
intake valve. Since each cylinder has its own injector,
fuel distribution is exactly equal. With little or no
fuel to wet the manifold walls, there is no need for
manifold heat or an early fuel evaporation system.
Fuel doesn’t collect in puddles at the base of the
manifold. This means that the intake manifold
passages can be turned or designed for better lowspeed-
power availability. The port type systems
provide a more accurate and more efficient delivery
of fuel.