PVC system catch can
Instructor
Joined: Aug 2016
Posts: 235
Likes: 28
From: Fort McMurray Alberta
If you block the freshair inlet of crankcase, and pull suction via intake manifold to crankcase, it will pull on every oil seal into the engine and ruin them.
So if you want to run this on the fresh air inlet, the size of hole you need to drill is equal to the size necessary to pull 10-40" of Water on the crankcase during idle speed. Better to go a little too large than too small to account for buildup of sludge over the years so make it bigger than you think it needs to be.
On the other hand, you can put that on the intake manifold -> crankcase side to disable PCV for cruise and idle. It will make the oil quality worse faster, it will reduce ring seal, possibly lowering compression and reducing economy, but overall it may improve WOT horsepower 1% or something. Better to have it hooked up for those benefits, the cost is so small. So one again, drill a hole, but don't oversize this one too much. A smaller hole is probably smart, less than 3/8" probably to start with, smaller than the fresh air inlet for sure. See what the suction is like on the fresh air inlet (using a gauge, shooting for 10" to 40" of water usually) open up the hole till you see that suction present with the appropriate hole on the fresh air inlet balanced to that vacuum.
So if you want to run this on the fresh air inlet, the size of hole you need to drill is equal to the size necessary to pull 10-40" of Water on the crankcase during idle speed. Better to go a little too large than too small to account for buildup of sludge over the years so make it bigger than you think it needs to be.
On the other hand, you can put that on the intake manifold -> crankcase side to disable PCV for cruise and idle. It will make the oil quality worse faster, it will reduce ring seal, possibly lowering compression and reducing economy, but overall it may improve WOT horsepower 1% or something. Better to have it hooked up for those benefits, the cost is so small. So one again, drill a hole, but don't oversize this one too much. A smaller hole is probably smart, less than 3/8" probably to start with, smaller than the fresh air inlet for sure. See what the suction is like on the fresh air inlet (using a gauge, shooting for 10" to 40" of water usually) open up the hole till you see that suction present with the appropriate hole on the fresh air inlet balanced to that vacuum.
Cheers.
Thread Starter
Melting Slicks
Joined: Mar 2008
Posts: 2,666
Likes: 289
From: Spring Park MN
Gotcha - makes perfect sense. I was going to leave my breather in the intake side valve cover. However the "flow and volume"" would be the same as before. I thought the little fittings with Blue hose would be to restrict flow on the PCV side but having it on the intake valve cover makes sense regarding slightly more balanced system, i'm if thinking on the same page?
Cheers.
Cheers.
Mike
Instructor
Joined: Aug 2016
Posts: 235
Likes: 28
From: Fort McMurray Alberta
If I need to I'll drill the one fitting and put the assembly in series with the PCV line.
Last edited by Ryan Menzies; Feb 6, 2018 at 08:56 PM.
