The IAG Performance Competition Series billet aluminum Air/ Oil separator for the 2011-2014 Subaru STI vents crankcase vapors to the atmosphere. The AOS's approximate 1 liter capacity, fully heated housing, superior breathing and unique patent pending baffle design sets it apart from the rest. The AOS features a 180° breather port rotation for install ease, large breather port and a greater pressure stream oil separation. As air and particles of oil enter into the AOS, the largest particles of oil will collect on the inner surface of the can and drain to the bottom, the smallest particles will remain suspended in the pressurized stream. The air makes its way through the multi-stage baffle system, gravity pulls oil from the air. By increasing the diameter of the breather opening on the top of the AOS, IAG has drastically decreased the exit velocity of the crankcase vent stream.
The side of the Air Oil Separator features 3 port billet hose barbs. There are NO plastic fittings that require thread tape to seal. Each engine vent port on the 2011-2014 STI receives its own connection to the AOS. By giving each engine port its own entrance to the AOS IAG has allowed for more effective and faster excavation of crankcase pressure, additionally this will reduce the overall system pressure. With a 4" OD and 5.75" height, the AOS has an approximate 1 liter of holding capacity.
The bottom of the AOS is shaped like a snail that redirects positive crank pressure into a swirl pattern produced by the 3 side ports. Allowing maximum oil drainage while separating oil from the air in all the venting ports. IAG’s AOS collects oil and actively drains the oil to the crankcase under normal, off boost driving. The weight of the collected oil will easily overcome the pressure in the drain line, however under heavy boost the crank pressure will push back up the drain with the same air/oil mixture that is seen on the side ports.
The AOS comes with a supplied coolant hose that is built to exceed SAE J20R3 standards. It will withstand coolant temperatures up to 300°F. The back plate of the AOS features a unique coolant routing system that heats the entire AOS to the same temperature of the engine. This maximizes the evaporation of any water collecting inside of the can. The hotter the AOS, the less water will collect inside and mix with the oil.