Why does your Subaru need an IAG Air Oil Separator?

Most of us realize that the vast modification community is well aware that turbocharged Subaru engines have the frustrating Blow-by issue in their history. For novice enthusiasts or those new to the Subaru brand and its history, blow-by occurs when the normal combustion process within an engine causes fuel, air and moisture to be forced past the piston rings into the engine's crankcase. Obviously, an engine's piston rings must constantly maintain a specific and appropriate fit to contain this level of pressure. Worn piston rings and cylinder walls are less capable of maintaining this crucial seal. Also, as a vehicle ages depending on its use, the challenges it faces, and its level of performance, the amount of blow-by that occurs in the engine will most likely increase and pose more of an issue over time. Collected residue, assorted deposits, and invasive soot - all elements that appear on the piston rings over time due to an incomplete combustion process, can also contribute to serious blow-by. Turbocharged engines have much more cylinder pressure which creates more blow-by than a naturally aspirated vehicle. Subarus and vehicles with flat motors create more blow-by and push a lot of oil into the blown by gas. Since the Subaru's crankcase volume is really small, it becomes very pressurized and can see this problem more than other brands with turbocharged engines. A couple of known components and solutions that address this issue are known to enthusiasts as the Catch Can and the Air Oil Separator .

It is always encouraging when you find a company that is not only examining issues that affect motorsports performance, but also taking serious steps forward to develop smart solutions which can hopefully change factory designs and improve engine performance through very intelligent innovations and engineering. One team of game changers in the automotive industry is Maryland-based IAG (Integrity Auto Group) who has spent the past 20 years building their brand, their provenance, and their reputation to deliver problem-solving products to the Subaru community. In the beginning, between 2004 and 2006 , this group of enthusiasts was focused on the sales of their inventory of high quality used performance cars, primarily the Subaru WRX and STI platform. After 18 months of effort, the IAG team moved over 200 vehicles which prompted their client base to also provide services and aftermarket products for these Subaru models. Remaining agile and reactive to these needs, IAG went national by 2007 extending their reach to a country filled with dedicated Subaru owners who were hungry for performance and an innovative ally in their corner. By 2019, IAG Performance has grown to become a leader in Subaru performance with a fully functional facility designed to serve serious modifiers and enthusiasts throughout the nation. A company that understands the Subaru engine, IAG has spent decades sharpening their skills not only as engine builders, but also as contributors to the creation of some of the fastest automobiles in the world of motorsports.

As IAG Performance team became more exposed to the industry while being deeply embedded in engine building, component design, and engineering, they naturally became aware of common issues related to Subaru's engine functionality and how to use their innovative skills to address the obstacles and pitfalls that were directly affecting the success of the enthusiast. Confronting Subaru's blow-by issue was a natural course that this team needed to take. The IAG Air Oil Separator is a very sophisticated component and self-contained unit equipped with a set of features smartly designed to efficiently address these issues whether your vehicle is a daily driver or a weekend performer. Those drivers who have used a catch can as a solution will quickly notice, after the vehicle sits idle overnight, that the can is filled with ugly sludge - a nasty mixture of blow-by, condensed water, and fuel - a combination that should never find it's way back into the vehicle's crankcase. This air oil separator is designed with ports used for venting each valve cover and for the crank case itself. This will eliminate an excessive buildup of pressure in the crankcase. Extreme pressure in the crankcase will naturally affect the ring seal. If the ring seal is being negatively affected it may cause an amplification of existing blow-by and reduce the vehicle's overall power since the compromised rings are causing a leak in combustion pressure. The incorporated venting on the IAG Air Oil Separator will significantly limit crank pressure build up even in a small case design like Subaru.

If we were to dissect this component and inspect its interior, we would first notice the coolant hoses incorporated in the design. The IAG Air Oil Separator is designed to direct the output of the heater system through its smartly designed side manifold component which circulates the heated liquid through the unit that runs at the same temperature as the cooling system which, in turn, eliminates the condensates like water and fuel from returning to the engine. This design keeps the unit hot and causes these elements to be vented out efficiently. One important feature on the IAG Air Oil Separator, which also needs to be noted, is the angled hose port design which motivates the quick development of a swirling action or "centrifugal separation" of the liquid from the gas as they enter the separator. This swirling action in combination with the heated interior helps with the overall separation of these non-oil elements from the mixture, creatively vents out high pressure gas, all while making sure the oil returns to the crankcase without being a sludge-like substance. Most importantly, depending on if the car is operating in a daily drive or racing scenario, the higher pressure gas is either condensed further within the design of this mechanical separator before it returns to the engine or is vented to the atmosphere or before the throttle body. This process expels a clean air element unlike that with oil content which could result in detonation, falling spark plugs, or other issues which could affect overall performance or safety. Simply, once the air oil separator has gone through this process, the driver can be assured that any oil which is removed will come out the bottom of the unit while nice, clean gas is coming out of the top. 

IAG has produced a superior, innovative aftermarket solution for the Subaru which is bringing both the company and the air oil separator design into many conversations at events and tracks around the motorsports world. During a recent conversation with Kent Leach , a member of the Performance and Service team at IAG Performance , we had the opportunity to hear more details from the maker how their unique innovations started at their beginning and what led them to being a pioneering contributor in solving critical issues, thinking out of the box with their designs, and engineering a component that is a heroic save for Subaru's performance community. "IAG used to use a competitor's Air Oil Separator for in-house installations", Leach confirmed. "As we started building higher horsepower cars, the small breather line on their Air Oil Separator was insufficient and caused oil to be reintroduced to the inlet. We also wanted to introduce the use of coolant to heat the canister, eliminating the condensation typically present in Air Oil Separator systems of that time.", he added. IAG's smart design began to take shape and conquer some of the most persistent obstacles thrown in the path of many a Subaru driver's journey to performance success. "The restricted drain hole also acts as a vent during boost conditions," Leach said. "In our testing, we found that restricting that hole increased the amount of oil that entered the can through the other ports. To mitigate this we engineered a way to both drain and vent oil unrestricted while not disturbing the swirl path inside the can.", Leach proudly confirms. "We found that rather than using coolant simply as a way to thaw frozen liquid inside the can, we developed a full heating system to heat the entire body of the can to reduce the effective condensation internally."