Is venting your crankcase bad for your tune?
Feb 9, 2007, 03:16 AM
#31
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That is a bad idea....There have been many posts about the ill effects of doing this...Both outlets are essential to a the evo....And rather than VTA, folks should use a good catch can (or the like) and route back to intake and manifold.
Feb 9, 2007, 04:28 AM
#32
Here's a write-up I did with my "cheap catch can" install. It even has diagrams of the PCV system for those that are confused.
https://www.evolutionm.net/forums/sh...ad.php?t=51997
https://www.evolutionm.net/forums/sh...ad.php?t=51997
Feb 9, 2007, 05:41 AM
#33
try to keep the inlet tract clean and avoid the reduction in octane that oil mist can cause.
Have you checked your turbo inlet piping and intercooler piping? Where do you think all that oil vapor is going when under boost? By your post it sounds like you have a catch can between the cam cover and the intake manifold, but what about between the cam cover and your intake pipe?
Between pulling the intake piping to replace turbos, intercoolers, routine maintenance, etc., I'd rather "smell" that oil vapor/water/acid than have it end up in my intake track!!!!
Different strokes for different folks is what makes the world go round.
Have you checked your turbo inlet piping and intercooler piping? Where do you think all that oil vapor is going when under boost? By your post it sounds like you have a catch can between the cam cover and the intake manifold, but what about between the cam cover and your intake pipe?
Between pulling the intake piping to replace turbos, intercoolers, routine maintenance, etc., I'd rather "smell" that oil vapor/water/acid than have it end up in my intake track!!!!
Different strokes for different folks is what makes the world go round.
I just placed a trap between the preturbo pipe and rocker cover, and I placed another (in a series of two traps to get all the oil) between the PVCcheck valve (you know what that is, right?) and the intake runner port that tends to send oil to combust.
Look, no mater what the good old boy's say, I believe that the headspace in the cranckcase needs to be positive in respect to the head for most of the engine's operation. At high oil temperatures vopors of fuel, water, and some cases, methanol, need to be pulled out and recycled.
Without the negative pressure and a two way flowing loop the fumes end up going into solution with the oil which will break down it's properties
Feb 9, 2007, 06:17 AM
#34
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Ahhhhhhhh catch cans?
try to keep the inlet tract clean and avoid the reduction in octane that oil mist can cause.
Have you checked your turbo inlet piping and intercooler piping? Where do you think all that oil vapor is going when under boost? By your post it sounds like you have a catch can between the cam cover and the intake manifold, but what about between the cam cover and your intake pipe?
Between pulling the intake piping to replace turbos, intercoolers, routine maintenance, etc., I'd rather "smell" that oil vapor/water/acid than have it end up in my intake track!!!!
Different strokes for different folks is what makes the world go round.
Have you checked your turbo inlet piping and intercooler piping? Where do you think all that oil vapor is going when under boost? By your post it sounds like you have a catch can between the cam cover and the intake manifold, but what about between the cam cover and your intake pipe?
Between pulling the intake piping to replace turbos, intercoolers, routine maintenance, etc., I'd rather "smell" that oil vapor/water/acid than have it end up in my intake track!!!!
Different strokes for different folks is what makes the world go round.
The stuff you smell is just what happens to find its way out of the crank case imagine all the acids and moisture that's not making it's way out. The PCV system is there for a reason.
Feb 9, 2007, 06:22 AM
#35
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There is no change to the OEM configuration.
I just placed a trap between the preturbo pipe and rocker cover, and I placed another (in a series of two traps to get all the oil) between the PVCcheck valve (you know what that is, right?) and the intake runner port that tends to send oil to combust.
Look, no mater what the good old boy's say, I believe that the headspace in the cranckcase needs to be positive in respect to the head for most of the engine's operation. At high oil temperatures vopors of fuel, water, and some cases, methanol, need to be pulled out and recycled.
Without the negative pressure and a two way flowing loop the fumes end up going into solution with the oil which will break down it's properties
I just placed a trap between the preturbo pipe and rocker cover, and I placed another (in a series of two traps to get all the oil) between the PVCcheck valve (you know what that is, right?) and the intake runner port that tends to send oil to combust.
Look, no mater what the good old boy's say, I believe that the headspace in the cranckcase needs to be positive in respect to the head for most of the engine's operation. At high oil temperatures vopors of fuel, water, and some cases, methanol, need to be pulled out and recycled.
Without the negative pressure and a two way flowing loop the fumes end up going into solution with the oil which will break down it's properties
I think the debate is whether or not those vapors while under boost need to be vented back into the turbo inlet pipe or can they be vented straight to atmosphere through a simple breather? Obviously, when the intake manifold is under vacuum, you're pulling in fresh air through your breather that isn't metered, and sweeping all the nasty's out of the crankcase/cam cover into the intake manifold. But under boost, when the PCV valve shuts, I personally would rather have that nasty vapor from the crankcase going to atmosphere than back into the turbo suction. It's still a two way flow loop like you suggest.
Feb 9, 2007, 06:26 AM
#36
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again, I'm not advocating (and I don't think anyone else is) removing the PCV system. Keep the PCV valve, and keep it hooked up to the intake manifold so that it does see negative pressure during idle/cruise, and is swept clean by fresh air entering from A) tubing that is routed back to the pre-turbo piping or B) a simple breather filter. How'd did this get turned around to not having a PCV system?
Feb 9, 2007, 07:28 AM
#38
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Ahhhh catch cans
again, I'm not advocating (and I don't think anyone else is) removing the PCV system. Keep the PCV valve, and keep it hooked up to the intake manifold so that it does see negative pressure during idle/cruise, and is swept clean by fresh air entering from A) tubing that is routed back to the pre-turbo piping or B) a simple breather filter. How'd did this get turned around to not having a PCV system?
Having a duel can system that works for some time I can attest to the fact that the system flows in 2 directions. Your PCV valve will leak under high boost and metered air will escape to atmosphere, that will affect your tune and I believe that was the title of this post.
Saikou_kun FTW!!
Feb 9, 2007, 08:55 AM
#41
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Having a duel can system that works for some time I can attest to the fact that the system flows in 2 directions. Your PCV valve will leak under high boost and metered air will escape to atmosphere, that will affect your tune and I believe that was the title of this post.
Saikou_kun FTW!!
Saikou_kun FTW!!
Feb 9, 2007, 08:59 AM
#42
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All engines experience some amount of blow-by past the pistion rings and into the crankcase. It's totally normal. But too much blow-by is a bad thing. That's why some people blow out their dipstick, from the excess pressure in the crankcase from too much blow-by.
Feb 9, 2007, 09:39 AM
#44
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It's a simple ball, seat and spring...... the vacuum overcomes the spring pressure and allows the ball to come off it's seat. Boost pressure, along with spring pressure pushes the ball harder into it's seat. The higher the boost, the less chance you have of any leak.