reason for oil in the intake???

[03InThe11s]

OK. This probably is not Earth shattering info to some of you, however, today i pulled my blower, to 1. install the RR spacer, 2. install the even flow cooling mod, and 3. to update my port. so, to get at the head a little easier, i pulled the lower intake. Well, the small drain in the bottom of the lower intake leads to the PCV valve in the drivers side head, and back into the intake side of the blower. So, this thing is vurtualy pressurizing the crankcase. Does this make any damn sense to anyone? It seems like this design would introduce more oil into the intake track. I know its made for emissions, but hell, for one, its bleeding off boost, and two, its putting pressure where it isnt needed. Anyone know why its there?


edit. pcv valve does the opposite of what i was thinking... had a handitard moment.

 

[slonech]

you are definately correct... do a search for the oil separator mod... definately an item of debate by all cobra owners.

 

[PhillyCobra]

The PCV valve is in the driver's, not the passenger side. It is designed to shut under pressure and only open under vacuum, so your boost should not go into the crankcase. The passenger side head connects to the inlet before the throttle body, which sees a big vacuum when the blower is sucking, causing some oil to get into the intake.

 

[slonech]

my bad... i got confused on which side you were talking about... thanks phillycobra.

 

[03InThe11s]

your right about the pcv valve not letting any air in, i was thinking backwards. however, now my question is why the hell did they design the passage back to the intake? seems like all it does is recirculate air thats allready been through the blower. could be wrong though. and i know about the oil seperator, but im probably going to go another route to keep oil out of my intake.

 

[PhillyCobra]

The passage from intake to passenger side head is to make sure air ingested in cranckcase ventilation system circulation is filtered AND metered. Air sucked into intake via PCV in normal part throttle operation (something you want to do) should be metered by MAF as it makes its way into the cylinders to assure proper A/F without relying too much on O2 sensor changing fuel trims. This setup takes care of both of those needs and with normal blower pressures doesn't suck very much air into the intake from the passenger side (undesirable flow). However, when people up boost there can be a big vacuum in the inlet before the blower, sucking in oil vapor. This is why some people have moved to oil separators or open vents.

 

[03InThe11s]

yup. thats why im going with open vents. talked to a few people who know, and most of them do exactly that. there was more oil below my blower than i would like, so, instead of putting a filter on the system, the whole things going away.

 

[Romans8:28]

yup. thats why im going with open vents. talked to a few people who know, and most of them do exactly that. there was more oil below my blower than i would like, so, instead of putting a filter on the system, the whole things going away.

Thats fine if you intend to rebuild your engine every 10-20K miles.....
Most race setups are like this, but engine longevity is not a concern in that case

Modern engines that hope to survive 100K plus miles NEED a functioning pcv system!

 

[03InThe11s]

Thats fine if you intend to rebuild your engine every 10-20K miles.....
Most race setups are like this, but engine longevity is not a concern in that case

Modern engines that hope to survive 100K plus miles NEED a functioning pcv system!

may i ask why? as in, what good does it do to the motor? i know you cant just seal everything up, i understand that, but ive never heard of a pcv system helping with longevity. :beer:

 

[Ex President]

Thats fine if you intend to rebuild your engine every 10-20K miles.....
Most race setups are like this, but engine longevity is not a concern in that case

Modern engines that hope to survive 100K plus miles NEED a functioning pcv system!

Yes... Please explain further.

Cause this sounds like an old wives tale. :rollseyes

 

[Kevin the Clean 1]

... with normal blower pressures doesn't suck very much air into the intake from the passenger side (undesirable flow). However, when people up boost there can be a big vacuum in the inlet before the blower, sucking in oil vapor. This is why some people have moved to oil separators or open vents.

So is it safe to say that my 04 COBRA that still has the stock pulley wont have much oil in the intake track & all... ? :shrug: I just want to clear up things for my car!

THANKS! :beer:

 

[CWD]

Mine didn't stay stock long but..

When I started modding after a long 3 months and less than 1200 miles I was shocked at the oil in the plenum when I removed it to put on a new Accufab T/B! I thought something was broken! Didn't take me long to write the "Make your own oil seperator for $21 dollars" thread. Now look at it and you'll see the value of that mod. :read:

 

[phillySVT]

I just changed intake and injectors on my car. I was shocked @ how much oil poured out of my TB. Especially since the car hasn't been driven in 90 days. Just turned on twice. It literily poured out when I removed my tb. I went to an open air filter on my passenger side.

 

[Romans8:28]

Yes... Please explain further.

Cause this sounds like an old wives tale. :rollseyes

Google on the function(s) of modern PCV systems and you can read through hundreds of sources outlining what condensed blow by gases can do to an engine.........

Here is a cut-n-paste from Wikipedia:

As an engine runs, the crankcase (containing the crankshaft and other parts) begins to collect combustion chamber gases which leak past the rings surrounding pistons and sealing them the to the cylinder walls. These combustion gases are sometimes referred to as "blow by" because the combustion pressure "blows" them "by" the pistons. These gases contain compounds harmful to an engine, particularly hydrocarbons, which are just unburned fuel, as well as carbon dioxide. It also contains a significant amount of water vapor. If allowed to remain in the crankcase, or become too concentrated, the harmful compounds begin to condense out of the air within the crankcase and form corrosive acids and sludge on the engine's interior surfaces. This can harm the engine as it tends to clog small inner passages, causing overheating, poor lubrication, and high emissions levels. To keep the crankcase air as clean as possible, some sort of ventilation system must be present.

 

[phillySVT]

Google on the function(s) of modern PCV systems and you can read through hundreds of sources outlining what condensed blow by gases can do to an engine.........

Here is a cut-n-paste from Wikipedia:

As an engine runs, the crankcase (containing the crankshaft and other parts) begins to collect combustion chamber gases which leak past the rings surrounding pistons and sealing them the to the cylinder walls. These combustion gases are sometimes referred to as "blow by" because the combustion pressure "blows" them "by" the pistons. These gases contain compounds harmful to an engine, particularly hydrocarbons, which are just unburned fuel, as well as carbon dioxide. It also contains a significant amount of water vapor. If allowed to remain in the crankcase, or become too concentrated, the harmful compounds begin to condense out of the air within the crankcase and form corrosive acids and sludge on the engine's interior surfaces. This can harm the engine as it tends to clog small inner passages, causing overheating, poor lubrication, and high emissions levels. To keep the crankcase air as clean as possible, some sort of ventilation system must be present.

So wouldn't an open air filter on the passenger side just realease these gasses into the air? And the oil would collect on the filter? Or am I missunderstanding something? So ifI use a filter (on the passenger side) instead of putting the gasses back into the intake. This has some sort of negative effect on engine life I would like to know before I run this set up. But I just don't see it from that explanation.

 

[Romans8:28]

So wouldn't an open air filter on the passenger side just realease these gasses into the air? And the oil would collect on the filter? Or am I missunderstanding something? So ifI use a filter (on the passenger side) instead of putting the gasses back into the intake. This has some sort of negative effect on engine life I would like to know before I run this set up.

Yes........

Open air filter on the passenger side is the optimum way to go (this is the fresh air intake into the pcv system to begin with), BUT do not remove the pcv valve and discharge to the intake tract. The system needs the vacuum to draw the gases out of the crankcase.

Oil is only being expelled on the passenger side while the engine is under boost, normally air is drawn INTO the passenger side (during a vacuum operation.......... idle, light load, cruising, etc)

 

[03InThe11s]

ok. so here is what im going to do. i have a open filter on the drivers side head, however, the pcv valve is still there and intact (that will eliminate any unmeterd air from entering the engine. and im going to maintain the return to the intake on the pass. side, however, im going to pull the valve cover, and install a metal mesh, hopefully to remove the oil from the intake. i personaly dont like the look of the air compressor fitting and additional hoses, so im going to try this and see if it works.

and Romans, thanks for the info. i try to learn something every day :beer:

 

[Kevin the Clean 1]

I still dont understand all this mess. So the ideal set-up is a open breather type filter on the passenger side & an oil-vapor separator on the drivers side...? Is this correct? :shrug:

 

[Romans8:28]

I still dont understand all this mess. So the ideal set-up is a open breather type filter on the passenger side & an oil-vapor separator on the drivers side...? Is this correct? :shrug:

Yes.........

But be aware that some people will argue that an open breather on the passenger side will allow for un-metered air to enter the crankcase and possibly affect your tune (to the lean side)

 

[Kevin the Clean 1]

Yes.........

But be aware that some people will argue that an open breather on the passenger side will allow for un-metered air to enter the crankcase and possibly affect your tune (to the lean side)

Thanks for the reply bud. :beer:

I guess I will just stick to the catch can on the drivers side. This will reduce most of the vapor from entering into the intake track & intercooler right? :shrug: