Anyone that has taken the PCVvalve off their LS1 car knows it is usually full of oil. This oil gets sucked into the intake and greatly lowers the octane of the fuel causing more knock than you would believe. The simplest thing to do is put extra filters in the line to try and cut down on the oil making it to the engine. The problem is you then have more filters you have to keep track of. This setup is harder to install but once it is done you will never have to think about it again. It also eliminates 100% of the oil from the intake and if you run a boosted engine then you don't have to deal with pressurizing the crankcase with boost from the intake getting past the pcv valve. This setup also pulls more suction the faster the engine is running so it doesn't drop to near 0 suction when you are at wide open throttle like the stock PCV and extra filters setup.
I have had this setup on my car for a month and am happy to report that not only has it got rid of all the knock, I have noticed that I picked up 1-2 mpg since I have done this. I didn't get a perfect seal on one of my welds on the tailpipe and noticed it has a slight bit of oil around it so I am happy to say this setup works perfectly to get rid of the blowby and suck it out without having to burn it. I also had to turn the idle screw up a bit since the car is no longer getting extra air through the PCV valve it would die sometimes. The idle screw is a torx screw that is under the throttle stop in the throttle body, it is easy to adjust.
Parts I used:
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Well first thing is to find a spot to mount the evac units in the rear of the car. I used a pair of spots that have a slight bend in them from the factory. Drill your two 7/8 holes in those spots.
make sure you put the tips inside the pipes the proper way. I used a metal bar to bend the opening a bit so the tip would fit in the pipe at a good angle. working with one side at a time I then used a rubber tie down strap and some shims to get the valve sitting in the position I thought it would work best. I hooked the hose to it and put a plastic bag over the other end sealed up with a rubber band. when I started the car I could see how much suction I was getting by how fast it sucked the air out of the bag. I messed with the position of the tip until I got them to have as much suction as possible. I tack welded them in place as I did and then rechecked them to make sure they were still getting a suction on them. After both sides were tack welded and positioned properly I went ahead and welded them down secure. I then ran the hoses like you see in the picture.
One thing you have to do when figuring out if they are working is to remember that just because the engine is at a high rpm it doesn't mean that there is enough air coming out the pipes. It will pull the best suction at wide open throttle but you can only test it for just a second then it will quit pulling air when you left off the gas. After hooking it all up I was curious so I put a vacuum gauge on it and put it under a wiper then took off on a wide open run down the road and the best I saw it was pull 4 inches of vacuum. The gauge moved where I wasn't able to see it so it could have possibly went higher as the RPM's went up but I didn't bother trying another run, it isn't important how much vacuum it pulls as long as it pulls some.
There are some holes so you can zip tie the hose in place. run the passenger side over to the drivers side and using the Tee fit them all together with the 3/8 hose running toward the front of the car.
I cut a short section of 3/8 hose and stuck it inside the larger hose then put it on the Tee, this worked well and didn't require any extra adapters and clamps. I then ran the hose toward the front of the car. I tied it to the exhaust hanger and then ran it along side the fuel lines towards the front of the car.Once I got to the transmission crossmember I crossed in front of it to the passenger side of the car. From there you can run the hose up the side of the bellhousing and come out behind the passenger side valve cover.
The illustration is hard to see but you can look at the one on your car. The PCV valve gets its air from both valve covers from a hose running behind the engine. There is a rubber Y connector back there you probably can't see but can feel. Disconnect the PCV valve and cap the hole in the intake. Take the hard pipe that is running to the back and get all the clamps off it so you can move it around. I had to take the insulation material off it before I could get them all off. Once you get it free you can give it a yank and pull it out of the rubber Y connector. When it is out all that you have to do is cut that pipe a few inches away from where it connects to the Y and clamp on your 3/8 hose then push it back into the Y on the back of the engine. If the engine is hot you will burn yourself up trying to get it together so make sure it is cool first.
The only other thing left to do is unhook the fresh air line that goes from the throttle body to the passenger side valve cover and plug both ends of it. I just inserted a rubber plug into the hose then put it back on since I couldn't find caps in my junk box to fit both ends. It would also work to plug the intake side and put a standard air breather on that hose but I don't feel it is needed.
If you want to comment or ask questions on this setup go here for the discussion thread