Crank Case Evacuation Ideas.........Maybe I'm Off Base

Alex in Houston · 02-03-2005

In order to help with crank case evacuation under boosted conditions, I have fabbed up a catch can with a K&N breather on top. Nothing fancy or outright ingenious about that. Stay with me here as I try and describe how I'd like to plumb it

The turbos always create suction (vacuum) on the inlet. The faster they spin, the more vacuum they create. On the bell inlets of my turbochargers (T3/T4 units from a Pair of Grand Nationals) they have 1/2" nipples that would attach to, I believe the valve cover on a GN. I would rather avoid sucking the oil mist from the crank case back into my turbo inlet (and thus into my blades and intercooler).
My design involves running a 1/2" line from each turbo bell to either side of the catch can. Then from the catch can, have another line that goes to the PCV location. This way the crankcase would see/have vacuum at all times and any oil vapor could be caught in the catch can (stuffed with steel wool/mesh). I have a drain cock on the bottom of the can to drain any/all oil build up (will do it every time I change the oil).
I've read where some say you can have too much vacuum, so I'm considering installing a valve of some sort in line to control the amount of vacuum that is actually alowed to reach the PCV location.
Should I just plug the PCV off and tap the valve covers? In tapping the valve covers, I considered getting a second passenger side one and chopping the neck down some (to fit under mt GT40 intake). Then just running a line from each of the filler neck nipples to my catch can.
So all in all, is this a valid idea/solution for Crank Case Evacuation?
All ideas/opinions appreciated and welcomed (I'm secure enough in myself to understand if someone tells me this is all poppy cock and a horrible idea, just validate your statement with reasons why)

Saleen91 · 02-03-2005

Hey Alex,

I replied to you on PoMoFo... but I've been taking notes from the Buick GN and Supra crowd. They seem to do this stuff, but without the little filter on the catch can.

02-03-2005

i would say it is valid.............as the boost is going into the motor, you are evacuating the excess blow by with your catch can,...........sounds right to me man......great job

KJMac · 12-29-2006

You couold buy a kit from summit that goes from your baffled valve cove down to you exhaust?

RoozterDVX · 11-26-2007

if any oil, mist/vapor, makes it into the intake stream, it will lower the effective octane rating of your fuel.
I tried the crankcase evac set-up from summit with the breathers, check valves and fittings which normally go into header collectors. I welded 1 fitting into the downpipe and ran the hoses into a tee then to the downpipe. Found that I had too much evac and was losing oil, (looked like I blew the motor at the top end of the track by the amount of smoke!)
I don't run any vaccum on mine now just the 5/8 hoses from each valve cover breather down to the sides of the tranny to avoid any oil dripping inline with my tires.

02-03-2005	#1
Alex in Houston Junior Turbocharger Join Date: Nov 2004 Posts: 17	Crank Case Evacuation Ideas.........Maybe I'm Off Base In order to help with crank case evacuation under boosted conditions, I have fabbed up a catch can with a K&N breather on top. Nothing fancy or outright ingenious about that. Stay with me here as I try and describe how I'd like to plumb it The turbos always create suction (vacuum) on the inlet. The faster they spin, the more vacuum they create. On the bell inlets of my turbochargers (T3/T4 units from a Pair of Grand Nationals) they have 1/2" nipples that would attach to, I believe the valve cover on a GN. I would rather avoid sucking the oil mist from the crank case back into my turbo inlet (and thus into my blades and intercooler). My design involves running a 1/2" line from each turbo bell to either side of the catch can. Then from the catch can, have another line that goes to the PCV location. This way the crankcase would see/have vacuum at all times and any oil vapor could be caught in the catch can (stuffed with steel wool/mesh). I have a drain cock on the bottom of the can to drain any/all oil build up (will do it every time I change the oil). I've read where some say you can have too much vacuum, so I'm considering installing a valve of some sort in line to control the amount of vacuum that is actually alowed to reach the PCV location. Should I just plug the PCV off and tap the valve covers? In tapping the valve covers, I considered getting a second passenger side one and chopping the neck down some (to fit under mt GT40 intake). Then just running a line from each of the filler neck nipples to my catch can. So all in all, is this a valid idea/solution for Crank Case Evacuation? All ideas/opinions appreciated and welcomed (I'm secure enough in myself to understand if someone tells me this is all poppy cock and a horrible idea, just validate your statement with reasons why)

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02-03-2005	#2
Saleen91 Medium Turbocharger Join Date: Nov 2004 Location: Tomball, TX Posts: 50	Hey Alex, I replied to you on PoMoFo... but I've been taking notes from the Buick GN and Supra crowd. They seem to do this stuff, but without the little filter on the catch can.

02-03-2005	#3
SuperDuty Posts: n/a	i would say it is valid.............as the boost is going into the motor, you are evacuating the excess blow by with your catch can,...........sounds right to me man......great job

12-29-2006	#4
KJMac Junior Turbocharger Join Date: Apr 2006 Location: Monmouth, OR Posts: 10	You couold buy a kit from summit that goes from your baffled valve cove down to you exhaust?

11-26-2007	#5
RoozterDVX Junior Turbocharger Join Date: Feb 2005 Location: Ft. Myers, FL Posts: 6	if any oil, mist/vapor, makes it into the intake stream, it will lower the effective octane rating of your fuel. I tried the crankcase evac set-up from summit with the breathers, check valves and fittings which normally go into header collectors. I welded 1 fitting into the downpipe and ran the hoses into a tee then to the downpipe. Found that I had too much evac and was losing oil, (looked like I blew the motor at the top end of the track by the amount of smoke!) I don't run any vaccum on mine now just the 5/8 hoses from each valve cover breather down to the sides of the tranny to avoid any oil dripping inline with my tires.