[O-cha]

So I've wanted to vent to atmosphere through a catch can just to insure there's no chance of any oil getting in after I get a clean intercooler in there so I did some "testing" yesterday to insure it's possible (not requiring vacuum to assist, didn't expect so but it's good to check). This "testing" consisted of taking the heater hose routed to the valve head and holding it out the window while flooring it down the street.

Still plenty of flow.

If you want to do this you need to know a few things A: it's very Illegal; B: you should do it through a catchcan to minimize the oil you spray where ever it's venting; C: You need a filter on the end to insure no particulate gets sucked backed into the valve head, this is not an option (or not optional, before I get jumped on, whichever you prefer)

[1clean335i]

thats how i had my catch can set up on the lexus...

[sdwilly]

Originally Posted by O-cha

So I've wanted to vent to atmosphere through a catch can just to insure there's no chance of any oil getting in after I get a clean intercooler in there so I did some "testing" yesterday to insure it's possible (not requiring vacuum to assist, didn't expect so but it's good to check). This "testing" consisted of taking the heater hose routed to the valve head and holding it out the window while flooring it down the street.

Still plenty of flow.

If you want to do this you need to know a few things A: it's very Illegal; B: you should do it through a catchcan to minimize the oil you spray where ever it's venting; C: You need a filter on the end to insure no particulate gets sucked backed into the valve head, this is not an option (or not optional, before I get jumped on, whichever you prefer)

Did this on my Eclipse years ago, had a little (very little) K&N Filter on the end.

[hotpants]

I had mine vented to the atmo on my SRT4 as well with a filter too. i went for a dyno session and noticed i was a couple hp short of where i felt i should have been. dyno operator suggested i reroute it back to the intake (which we did). ran it again and picked up 10whp.

just throwing my experience with this out there.

[M3EST]

Not bad.

[mwahlert]

Originally Posted by hotpants

I had mine vented to the atmo on my SRT4 as well with a filter too. i went for a dyno session and noticed i was a couple hp short of where i felt i should have been. dyno operator suggested i reroute it back to the intake (which we did). ran it again and picked up 10whp.

just throwing my experience with this out there.

very odd - normally venting pcv to atmosphere will help! because oil that enters the intake stream effectively lowers the fuel octane level and therefore reduces the amount of timing advance possible before knock.

[mwahlert]

o-cha - when you did this, did you plug the vac side?

[R1000K3]

That is what I'm doing to http://i407.photobucket.com/albums/p...s/FILE0072.jpg

[BSH Speedshop]

Originally Posted by mwahlert

very odd - normally venting pcv to atmosphere will help! because oil that enters the intake stream effectively lowers the fuel octane level and therefore reduces the amount of timing advance possible before knock.

While this is true, vacuum on the crank case provides the benefit of pulling pressure out of the engine freeing up internal restriction. It will also help the rings seal. We only suggest the VTA type systems on REALLY gross engines where the amount of blowby becomes such an issue that the performance gains arent as important.

[marconi118]

Si there is vacuum (or at least depression) in the intake pope to the turbo.

This means that the filter + airbox is restrictive! in a free flow intake there is no depression

[mwahlert]

Originally Posted by marconi118

Si there is vacuum (or at least depression) in the intake pope to the turbo.

This means that the filter + airbox is restrictive! in a free flow intake there is no depression

has this been measured?

[R1000K3]

Originally Posted by marconi118

Si there is vacuum (or at least depression) in the intake pope to the turbo.

This means that the filter + airbox is restrictive! in a free flow intake there is no depression

But even (or especially) with a free flow intake there is a high flow air stream, which will suck crankcase vapours with it if connected.

[raceyBMW]

Under boost(acceleration), there will be vacuum conditions in the pre-turbo intake piping...however under decel/idle there is no vacuum in the intake pipe. The crankcase vapors are routed to the intake manifold under no-boost conditions via a by-pass valve built into the valve cover. That's why a catch can will help prevent oil build-up in the charge pipes, but will not completely eliminate build-up on the valves themselves since under no-boost conditions crankcase vapors will still be routed to the intake manifold.

I think the best of all worlds would be to get the Macht Schnell DPs with EGT bung and route crank vapors to the exhaust...that way you still get the benefit of evacuation of the vapors from the crank and they still get passed through the secondary cats, assuming you have them still.

[mwahlert]

Originally Posted by raceyBMW

Under boost(acceleration), there will be vacuum conditions in the pre-turbo intake piping...however under decel/idle there is no vacuum in the intake pipe. The crankcase vapors are routed to the intake manifold under no-boost conditions via a by-pass valve built into the valve cover. That's why a catch can will help prevent oil build-up in the charge pipes, but will not completely eliminate build-up on the valves themselves since under no-boost conditions crankcase vapors will still be routed to the intake manifold.

I think the best of all worlds would be to get the Macht Schnell DPs with EGT bung and route crank vapors to the exhaust...that way you still get the benefit of evacuation of the vapors from the crank and they still get passed through the secondary cats, assuming you have them still.

you are saying that if routed into the exhaust, as long as the engine is running crankcase vapors are evacuated by the scavenging effect of the exhaust? as opposed to relying on vac in the intake pipes?

[raceyBMW]

Yes, that way no vapors at all back into your intake tract. Though the 90° inlet into the exhaust is not ideal, usually the kits for PCV exhaust evacuation have a 45° adapter to weld onto the exhaust/DPs. However it does have the potential to gum up the secondary cats though...probably best if completely. Others have built specific vacuum pump systems for this as well, though those are usually only used in drag racing conditions, where they can actually have an affect on HP (think 1000+ hp engines here).

Do a google search, you will find many applications in Supras/Nissans/Vettes/VW's etc.

edit: Here are some good thread about it http://www.honda-tech.com/showthread.php?t=1199935
http://forums.vwvortex.com/zerothread?id=4387972&page=1

[mwahlert]

Originally Posted by raceyBMW

Yes, that way no vapors at all back into your intake tract. Though the 90° inlet into the exhaust is not ideal, usually the kits for PCV exhaust evacuation have a 45° adapter to weld onto the exhaust/DPs. However it does have the potential to gum up the secondary cats though...probably best if completely. Others have built specific vacuum pump systems for this as well, though those are usually only used in drag racing conditions, where they can actually have an affect on HP (think 1000+ hp engines here).

Do a google search, you will find many applications in Supras/Nissans/Vettes/VW's etc.

edit: Here are some good thread about it http://www.honda-tech.com/showthread.php?t=1199935
http://forums.vwvortex.com/zerothread?id=4387972&page=1

my friend has a 402ci ls motor, and even in his power range (550+rwhp NA) gains are to be had from the vac pump systems..

[jippii ensio]

Originally Posted by raceyBMW

I think the best of all worlds would be to get the Macht Schnell DPs with EGT bung and route crank vapors to the exhaust...that way you still get the benefit of evacuation of the vapors from the crank.

Can you compare the crankcase vacuum using exhaust scaveningen with the vacuum by the stock arrangement? The vacuum is needed for freeing up the engine.

[hotrod182]

I tried the vent filter to atmosphere. Not only was the odors bothersome during boost operation, but in my Vbox testing, I actually lost trap speed.

I have spent a bit of time inspecting my crankcase ventilation system, and found the factory system is pretty elaborate. There is a valve that controls where the crankcase vents to. During vacuum, decel, it goes straight to the intake manifold. During boost, idle, it goes to the rear air intake before the throttle body. The valve in the picture controls the diverting. I'm still trying to figure out a way to verify that boost from the manifold isn't leaking back into the crank case ventilation system. Unfortunately most of the system is not accessible as it is built into the valve cover gasket. FYI the system spin the oil away from the crankcase vapors by means of the centrifigual cyclones. Those little cone shaped devices in the the valve cover. The control valve is to the left of them.

[jippii ensio]

Originally Posted by raceyBMW

Yes, that way no vapors at all back into your intake tract. Though the 90° inlet into the exhaust is not ideal, usually the kits for PCV exhaust evacuation have a 45° adapter to weld onto the exhaust/DPs. However it does have the potential to gum up the secondary cats though...probably best if completely. Others have built specific vacuum pump systems for this as well, though those are usually only used in drag racing conditions, where they can actually have an affect on HP (think 1000+ hp engines here).

Do a google search, you will find many applications in Supras/Nissans/Vettes/VW's etc.

edit: Here are some good thread about it http://www.honda-tech.com/showthread.php?t=1199935
http://forums.vwvortex.com/zerothread?id=4387972&page=1

How about not using the Macht Schnell DP bung as is, but using the bung by welding a connection to join the DP at 40 degree angle instead of the current 90 degrees?

[jippii ensio]

Originally Posted by hotrod182

I tried the vent filter to atmosphere. Not only was the odors bothersome during boost operation, but in my Vbox testing, I actually lost trap speed.

This proves that having the vacuum at the crankcase helps the engine more than what is the octane benefit of the breather. So the best bet would be sustaining the vacuum and then in addition if possible, to avoid the oil and vapors in the intake.

[O-cha]

Holy thread bump...

Originally Posted by jippii ensio

This proves that having the vacuum at the crankcase helps the engine more than what is the octane benefit of the breather. So the best bet would be sustaining the vacuum and then in addition if possible, to avoid the oil and vapors in the intake.

Vacuum in the crankcase IS a good thing. But him saying he has a Vbox test showing a loss in trap hardly proves anything at all.

Most of the benefits from having vacuum in the crankcase require building the engine from the ground up for that purpose. Otherwise you're talking about very small changes.


Someone measure the vacuum at that CCV port on the intake.

[raceyBMW]

Originally Posted by jippii ensio

How about not using the Macht Schnell DP bung as is, but using the bung by welding a connection to join the DP at 40 degree angle instead of the current 90 degrees?

No reason you couldn't do this on any exhaust, however you would want to do it post secondary cats so you don't gunk them up. It may not be an issue if you have a catch can inline as well.

Moroso makes some parts to make this easy.
http://moroso.com/catalog/categorydi...?CatCode=13023