I logged crankcase pressure and with a breather on a drilled out PCV, breather on driver's side VC nipple and NON-drilled valve covers, pressure got up to about 1.5 psi at 15 psi of boost. Not bad...

If I used more than a short length of 3/8" hose to locate the breathers remotely, the pressure went up rapidly. All depends on how much gas is making it past the rings...

 

most people are mounting their catch cans pretty far away thru tiny hose. I moved my breathers out of the engine bay to help with the smell drawn in thru the vent.

in the end you are right, it all depends how tight your motor is. and not every one is running alot of boost.

 

Rcdash, or any others.
I have a st TN kit on my Z. (Not sure if it natters).Should I so the pcv valve drill and put a breather filter on pvc and cap off lower plenum?? Lots of different ways to do of course.
Thanks.

 

Built motor or not? If you aren't a built motor you wont be running enough power to warrant messing with the breather system. I ran my stock venting up to 507hp without any issues.

It won't hurt anything to cap off the plenum and run a breather on the PCV other than increased engine smell coming into your car cabin.

 

Stock block at the moment. I went ahead w the drilled pvc/breather filter and capped plenum. Seems to be fine.
Thanks Jeff.

 

http://vibrantperformance.com/catalo...1022_1035_1069

Has anybody tried exhaust evac of the crankcase? Hose from each valve cover to the exhaust.

 

subbed.. looks like were all here in this one lol..

so... lost . Trying my hardest to learn the things to watch out for here.
I think this is the ultimate quest on a heavy boosted vq.. everyons system seems different.

Im blowing oil thru the back seals of a perfectly good turbo... no longer shooting my dipstick out, but i think the pressure has just found a new way to get out of the oil pan .

Going to have a lot of reading here to do this weekend.

 

Just put open breathers on all 4 ports as a test to see if that solves the problem. If it does, you can move forward with one of the many solutions...

My current set up is a very large Dynosty baffled catch can with all 4 ports coming into the can. Two large 10 an lines pull vacuum from near the intake filters for both turbos. Dynosty did a lot of testing to come up with a solution that eliminates all smell from the cabin even boosting beyond 20 psi. I get very little oil in the can but a large amount of what looks like a water/fuel mix.

 

With a forced Induction engine you can not have TOO much crankcase ventilation. Plus, the internal pressure plays heck on turbo seals.

Add some vents.


Three most common turbo problems:

Excessive heat (lack of cool down, small turbine)
Contamination (dirt)
Drain back pressure (crank pressure)

 

So with a built motor pushing around 500whp, sounds like running 2 breathers in the VC's and one on the PCV will suffice since I don't have a catch can installed.

 

2 caps and then then the pcv? Or you mean cap plenum, breather on pcv and breather on driver rear valve cover?

 

valve covers and pcv

 

The stock PCV should be drilled out and then a breather placed over it. No point in having something spring loaded in there. You can drill it out from the back with a drill bit dead center. With turbos you have a much better source for load appropriate vacuum -> the turbo intakes.

 

Mine is now tuned right at about 500. I'm spraying oil out of the breathers-pcv and driver rear. How would you guys route a catch set up?

 

And I don't understand what you're talking about herrschaft

 

Putting breathers on BOTH valve covers (where the hose connects the two) and one on the PCV valve.

 

That's how he's setup i believe. But under boost, oil sprays out of the breathers. It's kinda bad.

 

RCDash, did you have picture of your set up?

 

Actually, venting the valve cover or block into the engine via, turbo/intake/ wherever is a bad idea.

If you are moving oil out of the crankcase DO NOT feed it into the combustion chamber. Oil has an octane rating not much above ( 0 ). Oil in combustion can cause all sorts of issue.

If you are using a catch can AND it doing it's job trapping the oil only then should it return to the engine.

 

^ It is a very GOOD idea if done correctly with a proper, large, baffled catch can. Breathers are the easy solution since they release pressure which is goal #1. If you have additional goals of reducing oil spray in the engine bay and reducing vapors coming into the cabin then you have to get a little more creative and come up with a well engineered solution.

I do not have a picture of my set up, but until Dynosty actually measured crankcase pressure on the dyno it was difficult to know exactly what size hoses and how much ventilation was required. I will let you benefit from their research as I do not think they would mind. I have three 8AN hoses going to a very large front mounted catch can that has NO breather. One goes to the drilled out PCV valve. One goes to the rear valve cover opening. One goes to a tee in the cross over connection between valve covers. Then on the exit side of the can (past the baffles), I have two 10 AN lines leading to nipples on the turbo intakes fairly close to the filters. This set up draws sufficient vacuum and allows for proper escape of fumes throughout the rev range and load points (vacuum to boost). I no longer build crank case pressure. I do not suck up too much oil in the can. I do collect a good bit of oil, fuel (e85) and water mix in the can. If you want a similar set up proven to work on a 800 whp "loosely built" motor, you can call Dynosty to order the parts and install it yourself. They can make a catch can with and without an open breather up top. And yes, this is a large timing cover mounted catch can with 3 8AN nipples and 2 10 AN nipples. Not something you'll find on eBay...

I will say that in my attempts to get this to work myself I did not realize the importance of the size of the catch can. The larger the better.