Hey guys, I did some searching around, and I haven't found all answers to my questions on this topic, so I wanted to start a new thread and get some good info in here about this topic. I am looking to do a exhaust scavenging system for the PCV on my car. First, a little background on my setup I will be running. Mine will be for track use only. My downpipe consists of a 4" pipe, no muffler, that runs straight from the exit of the turbo to straight out of the side of the car. So on my setup, there should never really be any backpressure in the downpipe. Here is an old pic of the downpipe setup, but it is still basically the same routing, just different turbo.



I will be utilizing a catch can for my system. Not only because I already have it, but because I would hate to blow any oil out of the system and onto the track. I am also really interested in putting a MAP sensor connected to the crankcase so I can see just how much vacuum it pulls. Now on to the questions!

1. Will running a completely sealed system cause me problems with the rings seating properly? If so, what sort of vacuum should I be trying to target in the crankcase? I could then run a breather, and play with the sizes to get the correct pressure.
2. Is a check valve (or two) necessary for the system?
3. I would assume that you will want any and all O2 sensors upstream of this system, as to prevent it from reading lean by the oxygen entering the dowpipe at this point.
4. Does anyone have a part number for the check valves that most people use for these systems? I believe it looks like, or is the same as the one on the factory fbody.
5. Which configuration is best when running the pipe into the downpipe? I.E. which one would be the most effective.


I am very interested to see how much vacuum I can pull out of this setup, and it seems like a very simple system. Right now I just have both covers ran to a vented catch can (as you can maybe see in the first picture), and I am honestly hating this setup. Not only do I feel it leaves power on the table, but I feel no matter how well you plumb the system, you are still going to get a little pressure built up in the crankcase. Has anyone run a system similar to what I am wanting, and have you ever logged how much vacuum it pulls at WOT? Pictures of setups would be greatly appreciated. Thanks guys!

 

Wrong picture upload? LMAO!!!!

 

Did I miss something?

 

Look at your first picture you uploaded in your OP....your "old picture of your downpipe setup". Yes you are missing something. lmao

 

lol I'm still confused. The picture shows generally what my downpipe setup looks like.

 

It looks like an engine bay picture to me. What's it showing for everyone else?

 

Really? I dont know why but this is what I am showing on my screen lol It made me laugh

 

That's a pop up. I'm using the app so I don't get pop ups but it used to happen all the time when I was just viewing on the Internet.

 

Omg!!!! Haha! Yeah, mine is just showing the engine bay picture too, But I can now understand your posts. lol

 

Just my thoughts but if you get any vacuum with that setup it will not be much. Especially at full throttle.

 

Oh dont get me wrong, Im not questioning if it works. It absolutely will work. And it will work especially better at WOT versus other areas. Same concept as a carburetor.

 

I think the technical term would be venturi effect.....right?

 

The bottom one in your configuration pic will work the best if you rotate the tube 180 degrees. Search the instructions for the MOROSO pan evac system and you'll see that's the way they say to install it.

ETA: like this

 

#3 is how a standard evac system is plumbed. They work well, especially on exhaust without a lot of backpressure.

 

I guess it's me questioning. I know it is a good evac system but will it actually create a vacuum in the crankcase? I really can't see that creating much of a vacuum, at wot, with the crankcase pressure. Thinking it would just be pushing the pressure out that port. Again it is a good evac system, but I just don't see too much vacuum at wot. I'm no guru, just wondering. Only one way to find out.

I have my pump set at about 15in. No matter what rpm, at wot, it will not go higher than 10in. But, every motor is different.

 

That is correct sir.

Gotcha. Sounds like a plan. Thanks for the heads up.

Yeah cool man, nothing wrong with questioning things. I definitely am going to try to run a pressure gauge to the crankcase and monitor how much vacuum it can draw for me. It will be a while before I have results as I am in the middle of a build, but I will post them eventually.

 

Anyone have or seen back to back data logs with a pressure sensor in the crankcase with and without a line hooked to the exhaust? Even if you didn't get it into vacuum, it still probably reduces some pressure. Maybe you see 5 psi in the crankcase without and that drops to 1-2 psi with............I don't know.

 

You will not pull any relevant amount of vac. It will perty much act like a vent to atmosphere but without any chance of smelling blow bye. And is very simple and clean

 

Are you saying that it doesn't create a depression at all that is quantifiable (measurable)?

Do you have any back to bad data logs with a press sensor in the crankcase to prove or verify?

 

Will the down pipe eventually oil-soak and become stinky?