So a customer of ours was finishing an install and he had some great questions that really gave me an opportunity to explain the fundamentals of a catch can system. I learned from the master, someone that understands PCV systems better than most in the industry. Something he has always said is "There must always be a clean and a dirty side" and this has become extremely apparent to me over time. The flow of air must be considered when trying to understand the PCV system, the question must always be asked; where does the fresh air enter and where do the foul vapors exit?

There are a lot of oil separating catch cans out there that try to incorporate ventilation into the can in order to side step the clean side separator. The RX Clean Side Separator creates the necessary ventilation and provides filtration while keeping it a closed system, as long as the engine is running. My answers below will explain what I mean by my last statement. Check out the question and answer below and thanks for reading.

By the way the application is for a forced induction vehicle but his question and my answers are still relevant.


Hello Tommy,

I have a question on the oil cap/clean side separator. I'm wondering why using this is better than just using a t-connector into the on-boost (turbo cold side) connection? It seems to me using a t-connector accomplishes the same thing.
If you are referring to the vacuum line going to the turbo inlet, putting the ventilation here would kill the vacuum, think path of least resistance. The system works as efficiently as it does because we direct the flow of air. Put vacuum in and eliminate the resistance but have an entrance and an exit for the air to flow. Clean in and the dirty captured in the can while keeping it a closed system and not venting to the air.

A second question comes to mind. It seems that some dirty/oily air will come out of the crankcase breather hose as shown by you guys in your video. Is there a reason that this hose from the crankcase breather should not also be routed into middle dirty side catch can connector? In other words put a t-connection and join the primary dirty side hose with the crankcase breather hose.
What you are saying about air escaping would make sense if the engine wasn’t running. When the engine is running air cannot escape through the clean side. Because we have captured both primary and secondary vacuum, air is constantly being sucked in from idle to ¾ throttle and from ¾ throttle to WOT/BOOST. Also you can't run the clean side ventilation to the can, it's the air traveling from clean to dirty that contains the foul vapors.


After reading that I would like to say, the RX system is one of the more expensive kits out there but as the saying goes "You get what you pay for!" and this couldn't be more true. If you are NOT looking for the most effective kit out there than saving a few bucks isn't a bad idea. Our slogan is the THE SECRET SAUCE IS IN THE CAN! and this refers to our internal baffling system; it's a key component to the cans effectiveness. It is not the only thing that makes our system so effective at extracting foul vapors present in all direct injection engines. The other two key components here are the installation methods we instruct and something quite simple but often overlooked... the volume of the can and it's relationship to the baffling system. A lot of the inexpensive cans out there are just too small for the amount of vacuum produced by the engine which means the vapors come in and go right back out.

If the manufacturer doesn't consider the entire system it will be quite ineffective so when buying a catch can system consider the following: Baffling system in relation to vacuum present in relation to canister volume in relation to the flow of air as directed by the oil separating system.

Our system was designed by a GM trained engineer with a racing background. Please contact us anytime and if we are on another call, please leave a message and you will be called back.