Road racer

I am pulling my vacuum in front of a supercharger. It's tied in between the filter and the SC. I have consistent vacuum there. I tested crank case pressure using a cheap vacuum/boost gauge tapped into the back of the valve cover & ran the line into the car through the firewall. I was not able to actually detect any significant vacuum (or pressure). The system has worked perfect for me. I was filling up both Sakomichi (sp?) catch cans in less than 3k miles before. They were even mounted in the corners inside the bumper (in front of the wheels) to allow more condensation of the oil vapor. Provent 200 fixed my issues. They use Provent 200's on big turbo diesel tractor trailers.

Mijae007

The intake pipe, regardless if its in front of a supercharger, or turbo, or just the throttle body on n/a application, creates very little vacuum. If anything, it acts more like a vent. My vented catch can system has worked great too but now i want to reintroduce vacuum to the crankcase. The more i think about it i think there is only one way to achieve this the proper way...and that is with the use of two catch cans --one closed loop and one open loop.

The rear port would go to the closed loop catch can with a pcv in line back to the intake manifold. The front vent port would go to a vented catch can (can route back to intake pipe but not necessary).
It's essentially identical to the oem setup but with a catch can installed in-line to catch any oil overspill and blowby gases...this will allow constant vacuum when the throttle is closed and in driving conditions not in boost, and vent the pressure out when under boost.

yamahaSHO

If you want real vacuum at anything but idle, I you'll need a dedicated pump

Mijae007

ditto

yamahaSHO

I never stated I was after mass amounts of vacuum, so what are you trying to get at here? I have an AOS that is there to separate oil vapor and still remain a closed system. I have attained what I was after... Just as I have used this exact AOS in my street STi and the intake, intercooler, etc are still bone dry, 7 years later.

I have no idea how much "vacuum" is seen at the front of my turbo on the AOS outlet, but it's more than the factory setup when I'm at full tilt on track. I can design a lot of different systems, however, I don't like wasting time/effort/money into something past what achieves my goal. Good luck.

Mijae007

dude its cool...im not telling you to do anything. maybe ditto was the wrong word to use there but i was just agreeing with your last statement that more vacuum would require a pump of some sort. and i never stated you were after mass amounts of vacuum...i was. i also stated several times many people are probably running many different setups, and they all work subject to what the users' end goals are. i just wanted to open up discussion on different ways to plumb the lines or run single vs dual catch can setups to achieve constant vacuum if at all possible. but after more reading/research realized only way to have constant vacuum on and off the throttle is with a pump like you stated. so the next best thing is to run it like stock if you want "some" vacuum: when at idle or cruising/accelerating around town out-of-boost. Again, im not putting down anyone's design, your aos that you use, i just wanted to talk about it, isnt that what forums are for. a quick search shows vacuum has many good benefits, so why not try to incorporate it into our builds if and when possible?

i was getting at the fact that vacuum is very minimal at the front of the turbo...confirmed on my car too. again, to not confuse you a catch can or aos setup without vacuum will still work. its worked on my car even vented to atmosphere with absolutely no vacuum. but as stated before, it seems to act more like a vent at that location. im just making objective statements. take that fact and do what you want with it. hopefully some people planning to put together a catch can system can reference to these posts and design something that meets their goals. thats it. thinking out loud, posting my findings in the end these discussions are helping me design my own system and hopefully for others too.

illestrolla

To touch on your last point here, PCV valves not only serve as a 1 way, but also perform a metering function that prevents you from putting 20" of vac on your crank case.

Up until last season, I was running what I feel like is the most common setup for us FI guys. A single open can, with 2 extra -10 bungs added to the valve cover and everything ran to the vented can.

That setup worked fine-ish for 5-6 years, but I have always struggled with keeping my turbo dry.

As you mentioned in one of your previous posts, for us street guys, our cars spend a majority of their time at light load/idle. When I started really trying to solve my wet turbo problem, I took notice that even after short drives with no boost at all, I'd still get some oil in the compressor. After a few phone calls with my turbo guy, and some troubleshooting, I set out to conquer the crankcase pressure demons that many of us deal with.

I ended up adding a PCV back into my system (used the Radium PCV set w/ their boost safe PCV) off the stock PCV port, and back to the IM, while leaving the stock front port + my 2 additional -10 lines routed to the vented can. I do have a slashcut kit that I would like to add to my downpipe to help add some vac/draw to my front can, but for the time being, it's still completely open.

The result of this has been a considerable amount less crankcase pressure at idle/light throttle, and my turbo has stayed dry as a bone, finally.

Mijae007

@illestrolla thanks for your response. That's pretty much the same conclusion i've come to with this. I also realized trying out different setups that the horrible exhaust smell i keep getting a whiff of while driving is coming form my vented catch can, not the straight pipe exhaust like i had assumed. So yea, ideally I would like to run all my lines just like factory with the addition of closed loop catch cans to filter out the oil from the gases.

it would also be a good idea to run 1 or 2 more ventilation ports like you are also running through a closed loop catch can and back to the intake on the turbo for more ventilation. A well baffled oil catch can with stainless filter material should do the trick. I think i'm going to end up running the pcv port to a closed catch can back to the IM with a pcv valve in line. And run 2 to 3 vent ports to a closed loop catch can then back to the intake before the turbo. This should provide plenty of ventilation for the crankcase and draw out vapors at idle and low load. All the while also keeping smelly fumes from escaping the motor and into the cabin.

illestrolla

Yep, this is pretty much how I'm setup, but with my can being vented. I don't have room/an intake on my turbo, which is why I will be going with the slashcut kit eventually, until then I'm fine with the front can being vented personally.

yamahaSHO

I decided to update the AOS setup on my STi, similar to what I put on the S2000 as I have never been very happy with how I had my AOS being vented back into the intake, in any version I had. My first setup, I had the hose Y'd to two ports on the turbo inlet, just to keep up the volume, but it was a mess. When I did the new turbo setup, I tried to clean it up and use one hose, but that required me to reduce the 5/8" hose to something smaller to fit on the inlet. I don't think this kept up as I had some oil seeping out of the cartridge of the turbo. I could also never feel any vacuum on the hose when I disconnected it while the car was running (didn't even change how the car ran with that vacuum leak).

That said, I took my intake off and had a buddy weld up a port in it to not only keep the size of the hose consistent, but actually create some vacuum on the AOS itself. I need to finish taking the powder coat off and repaint it, but here's what I got.





Design is similar to what you would find in a PCV exhaust dump setup (I also did this on my S2000... I should test the flow on it too).



I was curious on how well it would draw some flow from the port, so I blew into the intake and put my finger in the port, and with it wet, I could feel air being pulled in at just the low flow of my breath. I took it a step further and used my air compressor to test...


I am curious to see how this works on both cars. I should have the STi back up and running today. The STi likely has a bit more blow-by than my S2000 as the forged slugs in it are pretty loose.