I am in the middle of installing my whipple and saw where some people were eliminating there PCV valves and useing K&N filters. Is this safe? has anyone done this and what were your results?
PCV valve
- Thread starter viperstang
- Start date
I personally do not like open atmosphere venting. PCV stand for Positive Crank Ventilation, once you pull the vacuum line off you are no long Positive or sucking the air out at anything below WOT. Its just a little vent.
I have done weeks and days and hours of research on this subject when I had my high HP civic. The only way the car would run properly and not smoke is if I connected the PCV to a vacuum with a check valve.
If your worried about spewing oil into your intake then get a catch can, filter, oil separator or something along those lines.
Im sure HUNDREDS of people on this site are willing to argue with how I feel about this, but its a personal opinion. Ive built hundreds of cars, owned performance shops, and personally owned over 100 cars in the last 10 years, and that is my own experience with the PCV system on cars.
I have done weeks and days and hours of research on this subject when I had my high HP civic. The only way the car would run properly and not smoke is if I connected the PCV to a vacuum with a check valve.
If your worried about spewing oil into your intake then get a catch can, filter, oil separator or something along those lines.
Im sure HUNDREDS of people on this site are willing to argue with how I feel about this, but its a personal opinion. Ive built hundreds of cars, owned performance shops, and personally owned over 100 cars in the last 10 years, and that is my own experience with the PCV system on cars.
Having vacuum in the cranckcase is always a good idea, it helps everything seal better, especially the rings. My PCV broke, and started allowing a lot of oil into the intake, causing smoke on shifts and decel after WOT runs. I replaced it with a breather, and it cured the problem, but I will be switching back to a PCV system with a catchcan when I get chance.
Installing my separator this weekend.
How does a PCV break?
Like this :bash:
It is a mechanical device that modulates the amount of pressure in the PCV system. The spring inside of the PCV valve is probably what failed in this case.
Not even a spring in it,just basically a check valve that can get gummed up.It should rattle when you shake it.
The spring became too weak to hold it shut with any pressure. It was basically just an open tube at this point. I took it apart to stretch out the spring, and it cracked when I snapped (No pun intended) it back together.
I`ve never seen a spring in a PCV valve!It must be a real light spring cause as I posted above you can hear it rattle when you shake it.Learn something new everyday.
All PCV valves have a spring in them, it shouldn't rattle. If it's that lose, then what's the point of even having the valve there?
It should rattle, brand new ones rattle. Rattle is good, no rattle is bad.
Quick question from a "pcv newbie"... if this was broke, wouldn't it cause the catch can to not fill up at all? If this is the case, this would answer a lot of questions for me lol.
Well maybe mine rattled a bit more than it should, because I could hear it in the cabin at certain RPMs and was positive it was the driver side head. Pulled the PCV out, replaced with a breather - haven't heard a tick since.
:bash: thats funny
I
The positive in PCV has nothing to do with the vacuum present in the PCV system. The word positive is used because there is an above ambient level of pressure inside the crank case which which is positive pressure. Vacuum is negative pressure, not positive. There are plenty of guys who are successfully running two breathers, or they are running two lines comming off of the valve covers to a large catch can that has a breather on it and is vented to atmosphere. This option prevents oil spray from getting on you clean motor. Many of them are above the 20 PSI level of boost and are not having any blow back problems in the cylinders.
If running the two breathers you essentially have two 1/2" holes venting any pressure building up in the crank case. If this does not keep the crank case from over pressurizing or pressurizing at all, then there is something wrong with the rings on the motor and you might have excessive blow by. I know you are speaking of your old civic, but that might have been the case. Either that or you only had one breather and that was not enough.
All of this being said, I still have the factory PCV system on my car. However, if I ever pull the blower and clean off the intercooler, I will be going to the set up that routes both valve covers to a large catch can that has a breather on it.
The positive in PCV has nothing to do with the vacuum present in the PCV system. The word positive is used because there is an above ambient level of pressure inside the crank case which which is positive pressure. Vacuum is negative pressure, not positive. There are plenty of guys who are successfully running two breathers, or they are running two lines comming off of the valve covers to a large catch can that has a breather on it and is vented to atmosphere. This option prevents oil spray from getting on you clean motor. Many of them are above the 20 PSI level of boost and are not having any blow back problems in the cylinders.
If running the two breathers you essentially have two 1/2" holes venting any pressure building up in the crank case. If this does not keep the crank case from over pressurizing or pressurizing at all, then there is something wrong with the rings on the motor and you might have excessive blow by. I know you are speaking of your old civic, but that might have been the case. Either that or you only had one breather and that was not enough.
All of this being said, I still have the factory PCV system on my car. However, if I ever pull the blower and clean off the intercooler, I will be going to the set up that routes both valve covers to a large catch can that has a breather on it.
how are you gonna go use both breathers and a catch can? Correct me if im wrong but the side they usually put a catch can is after the line that comes from the drivers side head...if you have breathers instead where would the catch can be connected to?
You are correct, however I am using the term Positive in the way that it is positively removing any crank case pressure. If you use a breather you are no longer Positively removing all crank case pressure, especially immediately after a WOT run. After a run when you decell you pull a vacuum that returns to positively removing all crankcase pressure.
Sure if you have an open atmosphere breather it will vent the crank case, but it will still have a slight build up. Its not being assisted as it would be with a vacuum connected, or a correctly ran PCV system.
Like I mentioned, Im sure there will be hundreds of guys that want to argue this till they are blue in the face, but after the last 10 years of doing this, the best thing for an engine, IMO, is to have a properly ran PCV system.
This is actually an incorrect statement. There was a thread not long ago discussing people running large catch cans and the same type of comments came up there.
This is the thread, which is worth reading:
http://www.svtperformance.com/forum...r-oil-catch-cans-where-did-u-mount-ideas.html
And this was my post there in an attempt clarify things:
There is a lot of confusion in this thread about how the PCV system actually works.
********** you have made some very big fundamental mistakes in your statements. "Positive Crankcase Ventilation" does not mean that the crankcase is held at a positive pressure, that is completely undesirable. Air flows from the crankcase through the PCV valve and into the intake under vacuum conditions, not the other way around.
This diagram helps explain how a closed PCV system works:
On our cars, when the intake is not under boost air is drawn from the passenger side port on the air intake before the throttlebody, through the crankcase where the moving air joins with the blowby that occurs around the pistons, and is then regulated through the PCV valve back into the intake manifold where the air and blowby is burned in the combustion process. The PCV valve has a very important job which is to regulate the amount of airflow at differing engine load conditions. If it didn't do this the engine would suffer the same symptoms as a vacuum leak, air would be uncontrolably sucked in and it would become hard to control idle.
Under boost conditions the PCV valve closes almost completely so that the crankcase does not become positively pressurized, and the crankcase is now ventilated by the small vacuum being drawn by the engine before the throttlebody on the passenger side valve cover.
The PCV valve is actually an amazing piece of technology, it is far from being a simple check valve.
Here is a description of how the PCV regulates differing flowrates of air at differing engine speeds, quoted from AA1Car Auto
"The flow rate of a PCV valve is calibrated for a specific engine application. For the system to function normally, therefore, the PCV valve must adjust the flow rate as operating conditions change.
When the engine is off, the spring inside the valve pushes the pintle shut to seal the crankcase and prevent the escape of any residual vapors into the atmosphere. When the engine starts, vacuum in the intake manifold pulls on the pintle and sucks the PCV valve open. The pintle is pulled up against the spring and moves to its highest position. But the tapered shape of the pintle does not allow maximum flow in this position. Instead, it restricts flow so the engine will idle smoothly.
The same thing happens during deceleration when intake vacuum is high. The pintle is pulled all the way up to reduce flow and minimize the effect of blowby on decel emissions."
This article describes the PCV system very well and it's worth the read:
Positive Crankcase Ventilation (PCV)
I hope this helps.
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Instead of breathers attached to the valve covers, imagine two hoses that are routed to a large pint size catch can that has a large breather mounted to the top of it. Essentially the same thing as running two breathers with the PCV lines all blocked off. The only difference is that you are allowing the oil mist to drip into a large catch can and the pressure to come out of a decent size breather. This is a good alternative to running two breathers because when you run two breathers they have a tendency to mist oil out of them, and you have to clean the oil out of them often to prevent them from clogging with oil.
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