Pod Filters

A pod filter replaces the factory air box with an open element mounted on the air flow meter or intake pipe. Less restriction and a sharper induction sound are the reasons to fit one; the trade is that the filter now breathes whatever air is in the engine bay.

Heat first

Hot engine-bay air is less dense than air from outside the car, so a pod filter sitting beside the exhaust manifold or turbo can give back what it gains. Look at where yours will sit: a filter in the cool side of the bay, a heat shield, or a duct feeding it outside air all help. Kits such as the HKS Racing Suction and APEXi Power Intake place the filter for a given car; an enclosed induction box is the alternative where heat is a problem.

Flange diameter

The filter's inlet has to match what it fits onto: the air flow meter, the turbo inlet pipe or the throttle body. Universal filters are sold by inlet size; GReddy's Airinx, for example, comes with 70 mm and 80 mm inlets. Measure the outside diameter of the pipe or meter mouth, in millimetres, and allow for an adapter flange where the two differ. Vehicle-specific kits include the flange and any bracket.

Filter media

• Dry media is the most common from Japanese makers: the HKS Super Power Flow's green three-layer polyurethane element, APEXi's Power Intake and GReddy's Airinx are all dry. No oil to manage, and washing and drying cleans them.
• Oiled media, including HKS's red two-layer wet element, uses a light oil to hold dirt, and is re-oiled after each clean.
• Foam elements trap dirt through their depth and are washed and re-oiled.

Replacement elements are in replacement filters, and pipes and couplers in piping, with the rest of the intake range.