How bad IS IT to run a breather on the Valve cover "T"?

[OM3GA]

I hear a ton of mixed results.

What i was going to do was run a hose from the front of the T to a catch can and then from the can back to the pre turbo intake tube.

However i have been hearing people say how its better to just put a breather on the can instead of running it back to the pre turbo intake tube.

One example of information is this here

"Pulling a vacuum on the catch can outlet is ideal for emissions and performance. And there are two ways to do this. One is to run a line from the catch can to the intake manifold (like stated above) and have a check valve in line so the turbo doesn't pressurize the catch can and crank case. When this is installed, you also need to run a line over to the intake pipe from the catch can. If you do not, then the turbo will spool, close the PCV check valve and effectively pressurize the crank case with blowby gases. BAD!

The second way is to run the valve cover vents to a catch can and then run a line from the catch can to the intake pipe. This way, it will always be under vacuum. However, this introduces oil vapors into the entire charge piping tract and lowers the octane value of the fuel. Not to mention it makes a mess of all the piping. BAD for blow thru MAF setups too.

I have mine vented to atmosphere like yours except I run a tube down below the frame rail and do not put a filter on it. My catch can filter clogged once and caused the engine to smoke like crazy. Looked like I was Spy Hunter."So is it bad to use a breather on the front of the T? It makes sense to me that it would be since there s no scavenging going on inside the engine but if i can avoid having to run hoses everywhere then i am down to do it.

I'll probably update this with more info i have heard later.

[codyace]

Proper PCV and Catch can setup:

Rear Block Vent to OE oil air seperator.OE oil air seperator to Valve Cover T (one side)Valve Cover T (other side) to Catch canCatch can to intake pipe

(and then obviously PCV valve to intake manifold on the back passenger side of valve cover)

Whoever said that oil vapor sucked into the setup will hurt performance or lower octane and or be bad is an idiot. Catch cans are baffled and or filled with wire mesh for a reason...

The above method is best for emissions, and performance. Certainly a custom valve cover with custom baffeling can replace the OE oil air seperator aspect of things, but you want quick and easy, this is the way.

A valve cover T just isn't the best for performance, and often time allows oil to spray all over from sloshing around. You also loose the vacuum over the top end of the engine aspect of things too.

Not the best pic, but you can see how it should be routed

[s13-t]

I ran a breather to the left of the T for about 2 months. It then plugged up and eventually dripped oil onto my manifold. I doubt it caused my PCV valve to go out but it did... then my dip stick came out whenever I hit full boost and I know it wasnt my rings cause I just looked at them before my rebuild.

So a breather isnt a good idea... In my opinion. also... The factory oil catch can is located to the right of the T then connects to the crank case vent tube. Then the left of the T goes to the intake BEFORE the turbo.

I would try to duplicate the OEM set up.

[OM3GA]

i just see random setups like THIS all the time



Like whats the difference you know?

[nelson8708]

The only difference is in the setup you posted there is no vacuum to help pull any blow by gases out of the crank case. When pressure builds up it vents into the catch can and then through the breather. I run my setup into the turbo intake.

-Nelson

[zach-Ka]

Not trying to thread jack OMEGA...But, Would there be any issues with runny a aftermarket catch can in place of the OEM one?I had a breather on mine for a pretty long time BTW no problems really. My oil seemed to get dirty faster though...

[OM3GA]

If you ran an aftermarket can in place of the stock one i dont think it would function the same since the original can actually catches the oil and puts it back into the engine.

The reason the oil gets dirty faster with the breather is because there is no vacuum helping the blow-by gasses escape which means not as much blow-by gas exits therefore it contaminates the oil quicker.

I hear thats the number one cause of spun bearings in SR's, well that and the fact that it does not hold enough oil to start with.

[zach-Ka]

Ok makes sense. That means I gotta re install mine.

[s13-t]

I run mine in the same way as the oem unit. It doesn't drain the oil but it definitely catches the gasses.