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Still a Class Act - Direct Fit Catch Can, Part 1 - Concept and Design

Posted: March 28, 2019

Categories: Audi S4/S5 3.0T Direct Fit Catch Can PCV Side, 2018+

What does Philadelphia Eagles' safety Malcom Jenkins and the B9 Audi S5 have in common? More than you would think, actually. Both are hardened powerhouses of speed and power wrapped up in the soft touch of luxury. I'm not an expert on athleticism (not even close) but it's no secret that Mr. Jenkins has spent countless hours in the gym training to perform on the field, much like the engineers at Audi likely poured over the fine details of the 3.0T that sits under the S5's hood. Both parties also need to be in peak condition to exert themselves to their max over the long haul. Where sickness and injury would slow number 27 down, the illness of blow-by can slow down this mechanical athlete.

Mr. Jenkins takes the stylish athlete one step further. Where his athleticism is an asset to the Eagle's defense on the field, he spends his off time flexing his creative muscles through his joint-ventured Damari Saville boutique in Center City, Philadelphia.

Bold. Chic. Powerful. Both describe the suits from Damari Savile and the B9 S-platform.

Over the years the S4, and the S5 as of recently, has metamorphosized into the beautiful, mean, and very, VERY green (in our case) technology-packed machine. Throughout its lifespan, the Quattro AWD system has had power supplied by the likes of five, six, and eight cylinders, from zero to two turbos, and an experimental supercharged phase before landing on the current "hot-V" single turbo, V6 layout.

With the covers removed, it's as if we're at the MOMA looking through a glass display of a turbo on a pedestal. The turbo is mounted within the V of the engine with the heads reversed from what is usually seen. The exhaust ports all feed through the center of the V, directly to the impeller. The upside is reduction in turbo lag, but now there is a huge concentration of heat in that one specific area.

Volkswagen Auto Group, with Audi under that sprawling umbrella, was on the forefront of direct-injection technology for their production vehicles back in the early 2000s. Where this new technology increased power and efficiency in their engines, there was, of course, a tradeoff. For example, the 2.0T powering the MKV GTI was notorious for carbon buildup on intake valves, which inevitably diminished every benefit of the direct-injection fuel delivery system.

This is not a good look for you intake valves. Years of poor maintenance without the help of detergent rich fuel washing over them allows carbon to take up a stranglehold on the intake cycle of your engine.

Enter the VAG breather valve. On the outside it's the makeover these direct injected vehicles need. Underneath that plastic are a series of chambers to help sift out the oil and blow-by contaminants before crankcase pressure is recycled back through the intake tract.

The VW/Audi engineers have learned their lesson, however. After seeing the serious side effects of unguarded valves, air-oil separators were incorporated directly into the PCV system to reduce the amount of harmful vapors that could eventually lead to carbon buildup. Specifically for the 3.0T TFSI, the crank case pressure is vented through bank two, but this air is run through a series of chambers known as impactors to slow the air and allow the oil and moisture to condense. The oil collects in a chamber at the bottom and flows right back into the pan, leaving mostly clean air to route back into the intake.

These are the inner workings of the air-oil separator breather combo valve. Crankcase pressure flows up through cylinder bank 2, before passing through the baffled chambers. The oil condenses and collects in the chamber below and the clean air is released through the master check valve. However, due to some limitations in space, not all the oil is condensed fully and can still pass through to the intake. (Via Audi)

It sounds like a perfect system, and we've actually witnessed the effectiveness first hand with the AOS mounted to the 4-cylinder TSI engines after only being able to capture the smell of blow-by in a prototype kit on the 1.8T Golf. However, with some more research on the topic and some more hands on experience, we found that this AOS system could use a helping hand.

This might seem like we're comparing apples to oranges here, but these intercooler pipes are from the 2.0T powered MK7 Golf R. This vehicle uses the same AOS breather system and yet we still saw intercooler pipes dripping with oil after stints on the dyno.

This is the PCV line pulled from our B9 S5 loaner vehicle. This specific car came straight from the dealer's lot and already had oil residue in the system.

The 3.0T's PCV system is a little more complex than most, so Jason already had his work cut out for him. Not only is there the built-in AOS system, but this system uses one line to feed to two locations, plus there is the need to keep the can from pressurizing under boost. The first step, though, is to find a spot to mount our catch can.

Jason works on creating a 3D model of the available space under the B9's hood with the help of our Faro Design Scan Arm.

If the B9 S4/5 is lacking in anything, it's the option for a manual transmission, but more specifically space under the hood. Using our standard compact catch can design (which usually gives us some more clearance when it comes to line placement) wasn't an option. The PCV lines for the Audi are much bigger than most applications, but we already had a lid designed specifically for oversized vent hoses.

Jason works to determine the precise angle that he wants to have the catch can mounted in the S4/S5's engine bay.

Our engineer found the perfect spot for this catch can, nestled snuggly in the opening by the driver's side strut tower and conveniently right next to the port for the PCV breather. This mounting location does require a beefy bracket and unfortunately limits the access for draining. The plan is to include a drain kit with this direct-fit system for ease of servicing, and as for the bracket, we put our fabricator on the case.

With the catch can in place, routing the lines was a cinch, but we found ourselves on the wrong side of a check valve. With forced induction vehicles, it's important not to let the catch cans become pressurized to ensure that the blow-by is flowing in the right direction and staying where it needs to. Finding the right check valve for this size, however, posed a serious challenge, and enough of one where Jason decided that we should make our own.

A look inside our new check valve that will keep catch cans on turbo and supercharged applications from becoming pressurized.

Our prototype direct-fit kit fully installed and ready for testing.

Even with the amount of time training, studying, and engineering, both Malcom Jenkins and the B9 S4 and S5 still need a helping hand to stay healthy. For the Eagle's teammate, he has his team, both on the field and in the business sector. For our Audi, you have Mishimoto and the catch can as backup for the PCV system. With our prototype installed, we set our S5 out on a 1000-mile test to see just how much support this can will actually provide.