Hey guys, I have a question about how everyone has thier PCV system setup. Originally, I put a breather filter on the valve cover vent tube, and left the PCV hose connected to the upper intake manifold. With it like this, the PCV would see boost. I know that it's a check valve and doesn't allow the air to get into the crankcase, but the blow-by gasses won't be able to escape under boost. My first question is if this would be a problem.

Today I changed my setup, and went to a hot-air intake and put the filter right near the turbo. I also moved the PCV hose and routed it to before the compressor, and installed a catch can in between. My concern is that the turbo really isnt pulling as much air through that hose as I had hoped. I put my finger over the hole in the intake pipe and revved the engine, and there really wasn't much suction. Does anyone see this as a problem? Should the valve cover vent be connected to the intake pipe instead? Any advice or comments are appreciated!

 

I would keep the PCV under vacume... thats what your in for 99% of your driveing. If you think about it, even N/A when your Full throttle the pcv isnt seeing any significant suction.
On my setup i have the PCV routed factory style and i vented the Valve cover vents to Post Maf / Pre Compressor intake tubing. This has been working for me just fine. Im not going to say its the only way however...

Just my $.02

Jeremy

 

Agreed.
Vent the valve cover breathers & put PCV to pre-compressor intake.

 

Well I changed my setup back to stock. By connecting the PCV before the turbo, it was getting no vacuum at all. I connected my boost gauge up to the pipe and it barely moved at all. I'm trying to figure out something better to do, but in the mean time, I'll deal with the rough idle.

 

Is there a way to put a one-way check valve? I've noticed that my vacuum is around 16-17inHg because I have one of those filters on my PCV

 

the pcv valve is a check valve.

 

Steve, that would work for the PCV valve side. I didnt want to pressurize my catch can, so right now its disconnected, but I could put a check valve between the manifold and catch can, and it would not see boost. However, It wouldn't work for the valve cover side. In order to solve the vacuum leak, the valve cover vent would need to pull in metered air. Since my MAF is on the charge pipes, an ordinary check valve wouldn't work. The valve cover vent pulls in air, the same way that boost would travel. Some sort of boost-referenced valve would work, but I'm not sure where to get one. If your MAF is before the compressor then you would just need to route a hose from teh valve cover vent to after the MAF in a non-charged section. I can't remember where your MAF is off hand. Is your PCV going directly into the manifold with a breather filter on the valve cover?

 

The best way to do it: use a vacuum pump and hook all of the hoses up to it so that you have constant vacuum in the crankcase (seals everything better, is known for increasing power). using a vacuum pump also keeps the nasty junk from the crankcase from going into the engine again.

the next thing to do would be to run them to the intake before the turbo to put a vacuum on them but then you'd be putting the stuff through the engine.

the next best would probably be to check valve all of the lines and run them to the intake manifold to get a vacuum to them from there.

the worst things to do are to pressurize the crankcase (leaving all lines on with no valves) and filter one line but leave the others connected to the intake. this causes a vacuum leak (and a boost leak if no valve is in place).

 

Mark, do you know of anyplace that sells a vacuum pump for cheap? The ones I have seen are $250+. I tried doing your second idea, but the turbo wasnt able to pull a vacuum through the hose. Right now mine is setup with a vacuum leak, but there is no boost leak since the PCV functions as a check valve.

 

i would search for a used oem unit should be much cheaper and they were used on alot of cars

 

mitivac sells a hand vaccum pump (keep the dirty thoughts to yourself ya pervs)

 

HAHAHhAHAHhAHaa....

would a hand vacuum pump work though?

 

Wonder what someone would think when they pull up next to you and look over to see you doing the "pumping" action there in the drivers seat?

I'm trying to work on a dual action vent for guys like Brad who have the MAF on the charged side. It'd have to be a vent in vaccume/non boost and closed during boost...

Or else we may just have to pump ourselves
Scott~

 

supposedly these are supposed to do everything we want, except for keep the gasses out of the engine. it would probably work though. a tiny bit pricey... but it might be worth it.

http://www.et-performance.com/krank_vents.html

 

Well I had time yesterday to take the breather element off the one side valve cover and re-direct it to just before the turbo inlet...
Wow.. there's quite a difference in throttle responce, smoothness in almost all areas. It did richen my fuel curve which I'll have to compensate for with Fuel press. or go back into the fuel maps and take some out.
Thanks Brad!!!!!!
~Scott

 

Scott, good to hear it helped you out! Let me know if you are gonna be around the shop sometime.

Mark, I looked at that site, but I don't think I understand exactly what it does. Is it just open air vented, and that thing somehow pulls a vacuum through the crankcase without an external source? The instructions also said that the engine must be completely air tight, and said what I interpreted as the need to block off the valve cover breather and oil drain on the pan. Is that correct?

Subs, would you, or anyone else for that matter, know what vehicles came with a stock vacuum pump?

 

i think those krank vents are just supposed to be a very good version of a pcv but meant to create vacuum in the crankcase instead of just vent the crankcase like a regular pcv (even though the name is krank vent). i'm not quite on tonight because i've had a few beers and they're starting to reall make me spin a bit... weeeee

here's quite a few various vacuum pumps i could find on ebay
http://motors.search.ebay.com/vacuum-pump_W0QQfromZR40

and interesting one:
http://cgi.ebay.com/ebaymotors/AUXIL...QQcmdZViewItem