DIY Two Way PCV System How-To (HoMedepoT style)
 

From boredom and experimentation, along with some ideas from d-series.org on bi-directional pcv systems like what you see on factory turbo cars, I decided to make my own.

I did everything from HomeDepot Parts.* Probably spent $30 including a catch can I incorporated into it.

http://67.168.197.110/catchcanpcv/diagram.jpg

The parts list:

Husky Air Compressor Filter w/ 3/8" NPT threads (air/water separator)
10' spool of 3/8" ID 5/8" OD Vinyl Hose
10 hose clamps to fit 3/8" hose
3/8" barbed T fitting
Two 3/8" NPT to 3/8" Barb fittings
Two 1/2" to 3/8" adapters (I used a gutted pcv valve for one of these, and a plastic piece I found at homedepot for the other, it was a last minute grab I almost forgot about)
2" piece of 1/2" Hose
2 stock honda PCV Valves (holy ---- theres one right there on your intake manifold!)
3/8" Barb to connect to your intake tube (your choice how to do this, I didn't do it cause I dont have a filter or anything)

Here's How to do it:

Step 1: put the 3/8" NPT to barb fittings into the husky filter.

Step 2: remove the stock PCV Valve and hose that runs to the Intake Manifold.

Step 3: Mount the Husky Filter (catchcan) in desired location.* I chose right behind the intake on the firewall.

Step 4: using a 1/2" to 3/8" adapter and hose clamps, connect the 'IN' side of the catchcan to the stock PCV valve location using some of your 3/8" hose.* This connects your catchcan to your breather box, without having to get under the car.

Revision:* Tho pictured here is a filter on the valve cover breather, its not a bad idea to T it into the line between the crankcase and the catchcan so taht the head is being ventilated as well, this however can be skipped without problems if you wish.

Step 5: Using a short piece of 3/8" hose and of course more clamps, connect the 'OUT' side of the catchcan to the 3/8" T Fitting.

Step 6: Continuing to the other side of the T fitting, using another short piece of 3/8" hose, connect the other 1/2" to 3/8"* adapter to the T fitting.

Step 7: Use the short piece of 1/2" hose you have to connect the stock Honda PCV Valve to the 1/2"-3/8" adapter that you just attached to the T fitting.*

Note: This is a good time to replace the PCV Valve, they're cheap, and its piece of mind, so do it.

Also, if you can find a pcv valve or check valve that has 3/8" barbs on both ends, you can skip the adapter and connect the pcv directly to the T fitting with 3/8" Hose.* I personally could not find one in stock anywhere in town, but if you can get hold of a 1991 Saab 9000 Turbo PCV Valve, I believe it has what you need.

Step 8:* Connect the 1/2" side of the PCV Valve to the normal port on the intake manifold where it normally connected before we started.

At this point you're almost done.* There is one open fitting left now, and that is the third barb on the T fitting.

Step 9: Connect a 3/8" barb fitting to the tube between your turbo and the filter on the inlet side.* Run a hose from that barb up to the open barb on the T-fitting.


Revision: although not pictured here, somewhere on the line running from the T to the turbo inlet, you should have another PCV valve installed that is reversed in direction.* That way when out of boost that line will be sucked closed by the intake vacuum and you will only be pulling air from the crankcase.

Note: On my car I do not run a filter or tube off the inlet, so I dont have a place to connect this hose.* However, having it just open vented should still at least let the crankcase breathe without restriction under boost.* I ran mine in front of the radiator and pointed it back toward the rear of the car.* Maybe the fan will provide some suction, lol

Step 10: You are done, make sure the port on the bottom of your catchcan is closed, and go rip some panties.* Just make sure to do it at 100% throttle, not 66% like hotrex does ( ----- :p )

What you have just created is a pcv system with two paths.* One one path the normal pcv valve will provide vacuum until you boost, at which time it will close.* On the other path, when the PCV closes in boost, the suction from the turbo inlet pipe will provide vacuum to pull vapors from the crankcase.* The end result is constant crankcase ventilation.* There is concern that sucking on the crankcase vapors from the turbo inlet would suck shitty oil gunk into the* turbo and then you'd be burning oil, but thats what the catchcan is for.* The catchcan location was chosen so that it was filtering the vapors before ventilating to either path 1 or path 2.

Here are pictures of the system installed.* Note I did this in about 1 hour, stopped to eat, and have not yet mounted anything properly.* This was just to get it in the car and on its way.

Re: DIY Two Way PCV System How-To (HoMedepoT style)
 

good job fooky :-* i was gonna do a similar set up and do a write up, but my car doesn't seem to want to stay in one piece long enough for me to do anything but replace pistons :P i'll give you your 15 minutes of fame.....

STICKEEEEEE

Re: DIY Two Way PCV System How-To (HoMedepoT style)
 

what you need is a D16 ;)

woo woo sticky! :-*

Re: DIY Two Way PCV System How-To (HoMedepoT style)
 

you ------- hypocrite ::)

Re: DIY Two Way PCV System How-To (HoMedepoT style)
 

hahah ownage...but geez i would have got black hose instead of that white clear stuff

Re: DIY Two Way PCV System How-To (HoMedepoT style)
 

I run the clear line to the turbo just so I can see if my air/water seperator is doing the trick

Re: DIY Two Way PCV System How-To (HoMedepoT style)
 

hrm, fook, after looking over your set up again, it's pointless to even incorporate the stock pcv set up in to this 'breather'. under vacuum, the pcv will be open (simulating the stock purpose) and boost, it will be closed and the crank case pressure will bypass up past where the 'stock' pcv use to be and then vent out through your open hose, correct, is this what you had in mind? however, when in vacuum, and the pcv valve is open, it is in fact just going to serve as a huge vacuum leak the way you have it set up. it'd going to pull from the IM, through the open valve and then pull air from the least restrictive location, which in this case would be your open hose that is used to actually vent the pressure under boost :-\

Re: DIY Two Way PCV System How-To (HoMedepoT style)
 

i had to re-read what you said a couple times.

under boost, no this would not serve as a vacuum leak, as the pcv would be closed, and if operating properly, no air is getting thru to the open vented hose

under vacuum, no it would not either, a pcv valve only allows flow 1 direction, into the intake manifold. for the open line to be a vacuum leak, the force of the engine vacuum from the pcv signal line at the intake would have to be weaker than that of the open hose hooked to the intake tube on the turbo inlet side, not really gonna happen until boost is built up, at which time the pcv closes anyways.

Re: DIY Two Way PCV System How-To (HoMedepoT style)
 

no, of course it won't be a vacuum leak under boost, there's no vacuum, the pressure from the crank case will go through the charcoal canister, up the 'stock' pcv route, in to your seperator, and vent out the hose, you're right, it will work properly under boost and the pcv valve will be closed. however, when you're in vacuum (idle and cruising), the pcv valve will be open, look at your pictures, vacuum will be pulling on the hose off the manifold, the pcv valve will be open, and it will be sucking air through the vent hose because that's the path with least resistance, it won't be pulling through the stock pcv valve route like i think you had in mind. one easy way to fix that though would be to put another one way check valve in your 'vent' hose that will be close under vacuum and open during boost (opposite of the pcv valve), then when in vacuum, the manifold would be pulling from the crank case as opposed to to open air from the vent tube how it is now. see what i'm saying? the way it's hooked up now (only thinking about vacuum, don't even think about under boost right now) would be the same as having an open line off the intake manifold, which is a vacuum leak.

Re: DIY Two Way PCV System How-To (HoMedepoT style)
 

I see what you're saying. You think that the open hose in vacuum will take away from the suction to the crankcase? I guess that could be considered an issue. Like you said tho, another checkvalve or pcv valve flipped the other direction would cure that.