Radium Air Oil Separator w/RHD Bracket - Subaru WRX/STI 01-07

A high powered modified engine tends to generate excessive blow-by oil and gasses. In these cases, an ordinary small catch can may quickly fill with oil and not be adequate. Like the Radium Engineering Catch Cans, the AOS (Air Oil Separator) kit is responsible for keeping blow-by oil and other pollutants out of the air intake and intercooler (if equipped) systems. The main difference is that an AOS system returns collected oil back into the oil pan so there is no servicing required.

IMPORTANT INSTALLATION NOTES:

• In order for the AOS to function properly, a port must be supplied on the engine for the oil to return through.
• The AOS must be mounted high enough in the engine bay so that the port on the bottom is higher than the oil return port on the engine.
• Engine coolant must be available to be routed to AOS in order facilitate heating it so that it functions correctly.
• Hoses/Fittings Sold Separately

Without a properly designed AOS, water condensation can develop and find its way in the oil pan contaminating engine oil. Engine coolant lines are routed through the Radium Engineering AOS in a specially designed heating chamber (shown above). This keeps the AOS warm and prevents water from condensing inside. Because water is more dense than oil, there is an integrated water trap found around the bottom perimeter that prevents condensation from descending into the oil pan.

For AOS crankcase plumbing, the valve cover vent(s) are routed into the top inlet where the stainless steel condensing material separates the oil from the gasses. The filtered liquid oil is collected at the bottom of the AOS and drawn into the oil pan. Meanwhile, the clean crankcase air can either be vented to atmosphere (VTA) or recirculated to the turbo air inlet pipe. Shown above is a plumbing example on a Subaru EJ engine.

With a properly operating system, the fluid level inside the AOS will be empty after sitting. If there is a possible return obstruction, simply unscrew the anodized billet aluminum dipstick for inspection. Conversely, the entire billet unit disassembles into 3 large pieces for servicing.

Benefits

• Effectively raises the octane and increases engine performance with cleaner inlet air
• Prevents oil buildup in the intake or intercooler system walls, throttle body, intake manifold, etc.
• Lowers hydrocarbon emissions

RHD Mounting Bracket Notes:

• Cable-Throttle Models with Cruise Control will need the PSR cruise control relocation bracket.
• Spacers are included to allow clearance of the fuel lines for the larger cans (IAG/Cobb). With some of the smaller cans however these spacers don't have to be used.
• Supplied hoses/fittings from certain catch can/AOS kits may not be sufficient to install their product in this new location. Additional hoses/fittings may be required and sourced separately. For example, some cans may only include straight fittings where 90-degree fittings will work best.

Included

• Machined alumium Radium Engineering AOS
• Anodized universal mount that permits 360deg rotation
• Two 5/16" barbed fittings for coolant lines
• Stainless steel hardware

Note: If operated in freezing environments, Radium Engineering recommends installing insulation sleeving (not included) over any hose exposed to cold air flow. This will help prevent the natural phenomenon of water condensation freezing and potentially clogging the hose.

Vehicle Fitment:

• 2001-2007 Subaru WRX (01-05 Cable Throttle Models require cruise control relocation bracket)
• 2001-2007 Subaru STI (01-05 Cable Throttle Models require cruise control relocation bracket)