After researching the archives, I have an idea how to restore the PVC system after the SC is installed. First let me explain why I would want to do this and I would appreciate comments on all of this information.

PCV 101
As it was explained to me, the Positive Crankcase Ventilation (PCV) system replaces the harmful exhaust blowby gasses, in the crankcase, with clean air. The blowby gasses can be corrosive and reduce engine life. The system is driven by manifold vacuum. Filtered air from the throttle body (atmosphere side), goes into the valve cover on the passenger side, through the head and into the crankcase. It displaces the exhaust blowby gases in the crankcase and goes out through the driver side valve cover through the PCV valve. Finally, it is pulled into the intake manifold and burned. I was told that the intent of the PCV valve is to a) minimize airflow at high vacuum conditions (idle) so that it doesn't act like you have a big vacuum leak or b) prevent backfiring from pressurizing the crankcase. It can't be both and from the mouth blow test, I believe it to be b).

The Problem
The system is not designed to handle the positive pressures induced by a SC. This would pressurize the crankcase and push oil out the seals. Who knows what else. The PCV valve may prevent this but may not be adequate.

The Solution
First, place a check valve in line between the PCV and the intake manifold that prevents positive pressure from going into the crankcase under boost. It seems to me that the PCV valve itself may be adequate for this task. I have been told that it is marginal.
Second, route the passenger side valve cover tube to a new "T" on the output of a surge valve. Currently, the surge valve dumps to air in the engine compartment. Accomplish this be adding a short section of hose to the surge valve output and T the line from the passenger intake into this. You would be pulling in filtered air, no significant pressure and the crankcase air could go into the intake and not pollute the intercoolers and SC.
Maybe add an oil catch filter between the PCV and the intake too.

What do you think?!

 

Carrollsupercharging.com offers a pcv system for blown cars. If you can't find it let me know I have a recent catalog of theirs.

 

I've been trying to get ahold of carolls supercharging ...no one answers, so you leave a message and no one calls back.........anybody know whats up?

 

http://forums.corvetteforum.com/zerothread?id=634276

 

I just install a d1 supercharger and had problems with the pcv setup by changing it around i got oil out of the top manafold never had the problem before it was coming out of the bolt holes i had to remove the bolts and fill with gasket glue. If you have and information or pics on what you did or how to fix please send me email at peter@laurelsdesign.com

 

:iagree: Here's mine too... slisula@msn.com

 

http://www.villagephotos.com/pubbrow...dername=Photos

 

And the problem is even worse because there's much more blowby past the rings on a SC engine. You have to relieve crankcase pressure or it starts pushing the dipstick out, pushing oil past seals, etc.

Anyways, supplying filtered air into the crankcase is easy- put a K&N breather element on one valve cover.

Pulling that air thru the crankcase and out of the opposite valve cover is harder. If you're using manifold vacuum, you need a valve that shuts under high vacuum (like the PCV) and also shuts under zero vacuum / positive pressure (when under boost). So you only want it open from maybe -5 in to 0 vac. I don't know any valve that does this properly???

You could just run 2 straight breathers like the good ole days.; it would relieve the pressure. I run breathers with hoses over to the SC air filter; it provides at least a mild vacuum to keep fumes out of the atmosphere.

 

Sorry if I sound stupid here, I'm just trying to learn.

Your saying installing two breeders on top of the valve covers would fix the crank case pressure issue? and even the possible intake manifold oil leek, and oil dip being pushed out?
If I understand correctly, the intake manifold base oil leak, the oil dip stick being pushed out are symptoms of the crank pressure building up wile the SC or TC is engaged? and the PVC isn't working because it was only conceived to work with a normally aspired small block.

Someone correct me if I miss understood.

 

Yes the breathers will relieve the crankcase pressure.

In fact with a pressurized manifold, the PCV will be open and some boost is going into the crankcase too.

You want to completely separate the crankcase venting from the intake: plain breathers, brathers with hoses to air filter, vacuum pump, etc.

 

How do you completely separate the crankcase venting from the intake ? do you just remove the PCV valve and weld a metal plate or metal plug at its place?


[Modified by TheStef, 12:33 PM 12/4/2003]

 

A couple of breathers in the valve covers would do it.

 

gstreak-

The method you describe is exactly what ATI uses on their kits, at least the used to. One way check valve on the PCV line, and a dedicated dump line for the crankcase. Maybe you can order a kit from them.