Throttle body spacer flange Fiat Fire engines 1200 - 1400 8v latest series with electronic throttle body square flange with round hole
Spacer flange Used to increase the capacity of the intake manifold plenum.
In general a larger plenum can reduce pressure variations inside the manifold when the intake valves open and improve volumetric efficiency in a given rpm range, improving maximum power by influencing dynamic cylinder filling and pressure waves, similar to a clearly much reduced natural “supercharging” effect.