macnewma

What do you guys think about going with something like this: Krank Vents ?

I could run this in conjunction with a catch can like the Greddy.

What do you guys think? How important is crankcase pressure and vacuum?

I am still up in the air about what to do.

Is there a downside to running a breather like a the Lindsey and not porting it back into the intake?

What about the potential for unmetered air by using a catch can with a filter on top and porting it back to the intake?

I want to do what is best for the longevity and performance of my engine and I am still a little confused.

Thanks for all the advice thus far,
Max

Mike S

I'll agree that you will suck in oil vapors, however with the greddy catch can inline I do not beleive you will suck in any oil. The stock air/oil seperator sucks, no doubt. Mine was an oily mess that coated my engine with crap and left oil in my intercooler tubes. As far as "unmetered air".....the stock system was designed using "unmetered air" and it functions just fine. I don't see how this is a real problem.

I think there are two problems here, just from my observations and reading others experiences. One, the stock air/oil seperator hole is too small. This doesn't allow enough vacuum on the crankcase system when you up the boost levels or have a worn motor(blowby on the rings). However, if you just increase the hole size I think Tony is right by saying that you'll just suck in more oil. Two, the stock air/oil seperator is just not very good at what it does. Vacuum from the turbo is not only supposed to pull any pressure out of the crankcase, but by creating negative pressure you are in theory allowing the rings to seat better and provide less leakdown. In big HP chevy motors this is worth 20-30HP, but I'm not sure its worth more than 1 or 2 in ours(just guessing here).

I think slightly increasing the stock air/oil seperator hole size and running an inline greddy catch can will allow you to retain a vacuum pull on the system (like it came from the factory) and not suck in oil. Tony seems to be doing this (minus enlarging the hole) and it seems to work well.

Tony are you having any crankcase issues at all? Blowing the dipstick out anymore?

That KrankVent thing looks interesting. Similar to what someone else on this board did with their oil cap. Someone here rigged up a valve on their oil cap that vented under pressure but maintained vacuum. The KrankVent is pretty spendy...but interesting. I still think the vacuum system has more benefits though.

macnewma

Thanks for all the input and help. Here is what I have decided to start with:

I am going to use a Jaz Mini Breather (p/n 605-375-05). I will plumb it 3 different ways and I will be able to switch between them.[list=1][*]I will run from air/oil separator to the Jaz, and Jaz back into the intake. I will pull the K&N off of the unit and cap it. The line from the jaz to the intake will have a valve. The valve will be open in this case. This case is like the Greddy.
[*]I will run from air/oil seperator to the Jaz, and Jaz back into the intake. I will leave the K&N on the Jaz and it will vent to ATM. The line from the jaz to the intake will have a valve. The valve will be open in this case.
[*]I will run from air/oil seperator to the Jaz. The line from the Jaz to the intake will have a valve and it will be closed. I will leave the K&N on the Jaz and it will vent to ATM. This case is like the Lindsey/Stef's.[/list=1]

I will try all three options, and I am not sure which one will provide the best performance. There are pluses and minuses to both situations.

I am also talking to ET-Perfomance about the Krank Vent and its application on the 951. I might try that and plumb it in series before the Jaz.

Once again, everyone was very helpful. I will post my results once I get the parts.

Max

Charlie944

macnewma, I look forward to reading your results. On my 83' Callaway w/ 86' 951 long block it utilizes the factory air/oil seperator, but then vents to ATM via a K&N breather filter. I am also looking to redo that setup if needed seeings how I will have the intake off. Thanks for all the info guys.

NZ951

I am going to do this soon also, I bought a Lindsey unit, but did not fit due to my clutch location. Fitting it in where the charcoal cannister was is a stroke of genius! So how best to plumb it? Still fed into the intake? I am about to mahe a cusom intake pipe as most of the pipes going to it are gone and I need to mount the intake temp probe properly etc.