Air pump supplies air under pressure to exhaust port near exhaust valve by either an external air manifold or through an internally drilled passage in cylinder head or exhaust manifold. This pressurized air, combined with hot exhaust gases, creates a secondary combustion stage and decreases tailpipe emissions.
The air pump is a belt-driven, positive displacement, vane-type pump that provides air for the air injection system. Air is received from a remote silencer/filter attached to air inlet nipple of pump or through a centrifugal fan on front of pump. The by-pass valve performs pressure relief. Air pumps are available in various sizes. Various drive belt pulley ratios permit a wider range of vehicle applications.