Drawing on 35 years of racing knowledge, the Crawford Performance Closed Loop Air/Oil Separator was engineered and designed to keep the motor oil where it belongs – inside the motor and out of the intake system.
In the stock configuration, the crankcase is vented to the intake system in three different places. When the oil enters the combustion chambers, it effectively lowers the octane of the fuel, leading to detonation.
Our Air/Oil Separator effectively removes the oil from the air coming out of the engine’s ventilation system via a two stage process.
The first step in the process is a large swirl pot, to use centrifugal force to remove the oil from the air. The air is then passed through a second chamber (see second step below), and extracted through the top of the AOS. Gravity then sends the remaining oil down the walls of the swirl pot and collects in the bottom of the AOS. At this point the separated oil sitting on the bottom of the AOS is returned to a baffled chamber in the center of the engine block.
The second step involves a second chamber located within the first chamber. As the separated air moves up inside the AOS, it must enter the second chamber before it can vent out the top of the AOS. The function of the secondary chamber is to remove any residual oil that may have made its way up the swirl pot. The secondary chamber also has a drain to return any separated oil back to the engine.
The Version 2 AOS incorporates an internal heater to keep it operating at the proper temperature. The coolant line that runs from the turbo to the engine is now re-routed through the AOS. This effectively equalizes the temperature between the AOS and the engine to avoid condensation which can occur within any AOS. This heater also makes sure the vaporized water leaving the motor makes its way through the AOS in vapor form, rather than condensing back into a liquid. This is a MUST in cold weather and a bonus for any climate.
Kit includes powder-coated air/oil separator, hoses, clamps, and all necessary mounting hardware. Choose from stock-location turbo and stock top-mount intercooler layout, stock-location-turbo-with-FMIC, or rotated-turbo-with-FMIC.
Fits all 2008+ STI.
SKU#: 08633A, 08633B, 08633C
Shipping Weight: 10.0 lb
Manufacturer: Crawford Performance
Category: Other Intake