IAG Air / Oil Separator | AOS

• 2008–2021 Subaru | WRX STI
• 2008–2021 Subaru | WRX

The IAG Performance Air / Oil Separator (AOS) is a valuable investment to protect and maintain peak performance in your Subaru. Developed through years of meticulous testing on standard and competitive applications, the design of the AOS offers unparalleled protection for your engine. This AOS features a 1-liter swirl pot canister made of cast aluminum. This construction significantly enhances the separation of oil from the PCV system before the PCV gasses are directed back to the intake system. The Air Oil Separator features an aluminum housing that has superior ventilation, and it incorporates an exclusive baffle design that sets it apart from the competition. It works with all fuel types, prolongs engine lifespan, optimizes crankcase ventilation, and seamlessly integrates with standard ECU settings, so no tuning is required.

The presence of oil within the engine's intake tract brings about a range of adverse effects, so preventing oil from entering the engine intake is crucial for avoiding premature mechanical issues and maintaining optimal performance. Initially, the oil coats the internal components of the intake, intercooler, and piping, which can potentially harm or prematurely deteriorate rubber or silicone hoses, eventually leading to compromised connections. Once the oil enters the intake tract, it has access to the intake manifold and then the engine’s combustion chamber. Oil inside the chamber has the potential to trigger detonation, pre-ignition, excessive emissions, smoke generation, power loss, reduced fuel efficiency, and in extreme cases, severe engine damage or even complete engine failure.

The IAG AOS is designed for effortless upkeep. Unlike typical catch-can systems, our Air Oil Separators operate without the need for routine draining and maintenance. Separated oil gathers on AOS can walls and slowly drains into the engine's crankcase. With the help of our unique heating system, the collected oil remains free of sludge, ensuring that there is no risk of reintroducing it into the engine. The substantial size of the AOS body allows for a safe and gradual oil drainage process, effectively removing the chance of overflow commonly observed in smaller catch cans.

The IAG Air / Oil Separator features a unique baffle system that captures the oil suspended in your engine's PCV gasses, which are then able to drain back into the crankcase. The AOS body's inlet hoses are set up to create an internal gas vortex, which is then filtered through a series of baffles. The baffles gather the oil while enabling the gasses to exit from the upper part of the AOS canister. As the factory PCV remains active, this allows the engine to generate a vacuum in the AOS assembly to draw out even more of the PVC gasses.

The AOS works with the OEM PCV system, while also providing a boost to its capacity. The AOS directs PCV gasses to the turbo inlet, using an upgraded PCV valve for additional suction and air-oil separation. For applications using ethanol fuel, the AOS provides protection against problems like oil dilution and lubrication issues. This is accomplished by capturing fuel vapors emitted from the oil and then reintroducing them into the intake tract for combustion. The AOS provides exceptional protection against oil entering the intake flow and oil dilution in the engine's lubrication system, exceeding the capabilities of the OEM PCV system alone.

The IAG Air / Oil Separator uses a unique heating system to solve problems found in lesser catch cans. In inferior models, hot PCV gasses pass through a cold pathway, which causes condensation that mixes with the oil and causes sludge. IAG’s upgraded design attaches to the vehicle’s cooling system, allowing heat from the engine to transfer into the AOS canister. By warming the AOS canister to the engine's temperature, condensation and related buildup are greatly reduced or eliminated.

IAG’s Air / Oil Separator includes a full set of custom length SAE Quick Connection lines that not only simplify the installation of the AOS system, but they also reduce the chance of leakage because they offer a more reliable and secure connection than basic hose clamps. Once installed, our AOS system has a clean, factory-look that integrates seamlessly with your Subaru’s engine.

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