PCV setup on a forced induction engine
02-09-2012, 06:35 AM
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Mine is also under vacuum, I strongly prefer to have a vacuum source to the crankcase. I ran with it just vented when I first put it together and the oil would stink like shitty e85 after 1000 miles or less. With vacuum, the oil looks and smells much better, and I've never had any nasty **** like that in my catch can, but I do get about two shot glasses of moonshine per week out of my can from the e85 vapors!
02-09-2012, 06:40 AM
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Also, I think the key is to get the airflow just right with the vacuum. I think if you are pulling too much air through the crankcase, it's inevitable to pull oil droplets/liquid though and fill your catch can. You don't need much airflow on the vacuum side, just make sure your vented side is large enough to allow any peak pressure to freely escape. This is just speaking from my experience.
02-11-2012, 02:26 PM
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I routed a line from stock PCV to just empty under the truck (until I get a catch can) and after I drove it for 10 minutes and parked it there was a puddle where the hose empties to the ground. Why do I have so much stuff coming out of the drivers side?
03-15-2012, 10:19 PM
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Under Boost in excess of 10lbs 20 rwhp gained.. cleaner engine, better life of seal's, and better oil quality.
03-16-2012, 11:50 AM
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If you aren't pulling vacuum on the crankcase you aren't positively venting, you're just venting... Ran into this issue on my olds and am seeing it now with my truck. White/brown slimy foamy sludge collects on the surfaces of the motor that cool faster then the rest (like insides of valve covers and the underside of your oil cap). There is a gazillion post thread on ls1tech on the topic (search "catch can routing").
Basically you would need to use the two sources of vacuum that your motor creates using check valves to switch when they are flowing. Manifold vacuum when pressure in the manifold is below atmospheric, and then the vacuum that exists between the air filter and the compressor inlet when the manifold is above atmospheric (under boost) and there is significant airflow. You would use a dual catch can arrangement and the cans should have some media inside that helps condense vapor and catch the slime/moisture in the can. The cooler the cans are the better they will condense vapor.
Schematics are on the thread, lots of good info there, some misleading as well though.
Basically you would need to use the two sources of vacuum that your motor creates using check valves to switch when they are flowing. Manifold vacuum when pressure in the manifold is below atmospheric, and then the vacuum that exists between the air filter and the compressor inlet when the manifold is above atmospheric (under boost) and there is significant airflow. You would use a dual catch can arrangement and the cans should have some media inside that helps condense vapor and catch the slime/moisture in the can. The cooler the cans are the better they will condense vapor.
Schematics are on the thread, lots of good info there, some misleading as well though.
