Denali08

In this case from where you will get vacuum to remove crankcase pressure when it idles (off boost condition).

I have the RevX dual check valve catch can. Driver side valve cover vent attached to one check valve and intake is connected to other check valve. The third non-check valved tap of the catch can is connected pre-turbo for vacuum when under boost. I run a vented oil fill cap.

I had to remove internal check valve that was in the vented oil fill cap or it would smoke at idle. Also, without the vented fill cap, it would smoke as hell at idle.

I'm not happy at all with the RevX tank as the catch can never collects any oil. The vented oil fill cap gets alot of oil on the small filter fitted on the fill cap???

Maybe the 3/8" hoses are not enough to vent under boost.

Ferocity02

iTrader: (59)

I've been running a single 3/8" line to the turbo inlet to vent in boost and so far haven't had any problems. It's not pushing oil out the seals or the dipstick. I've been meaning to up the size of the hose to 1/2 or 5/8" just in case.

Denali08

Then it will need larger fittings/taps not only the hose itself and probably a larger catch can.

Ferocity02

iTrader: (59)

Yep, I'm going to tap a new breather line into the oil fill cap since they are relatively cheap and easy to machine, and I haven't been running a catch can between the turbo inlet and the valve cover. But I do have one in the stock PCV line with a check valve also.

Choda

iTrader: (1)

Won't it always have vac being mounted in front of the turbo because the turbo is always pulling air into it. It would produce more vac the more your in the throttle.

I really wish I had the time to test this crap. I have a full shop w all the tools and gauges to do this. At idle I don't think the turbo vac would pull 18 inches like the intake would but I think anything near that would work.

Ferocity02

iTrader: (59)

How much vacuum the turbo pulls depends a lot on how restrictive the filter and pre-turbo piping it. Regardless, at any feasible mounting location for a fitting, the turbo will never pull anywhere near as much vacuum as the engine. From my experience, the turbo inlet does not have enough vacuum to vent the crankcase faster than blowby is created. So at all conditions I feel like the engine is pushing the blowby into the turbo inlet more so than the turbo sucking it in, if that makes sense (this is why I kept the PCV system for out of boost driving). I did try hooking a vacuum gauge to the turbo inlet and revved the motor a good amount and the gauge didn't budge from zero. But of course this was stationary in neutral. In gear with more load I suspect the turbo would create more vacuum. I'd be interested in hooking up the gauge again and taking it for a spin to see just how much vacuum the turbo inlet can create.

Denali08

Will it make any difference to mount the vac line to the compressor cover or to the cold air pipe in front of the turbo?

Some compressor covers come with a tap for fitting on the front cover. Mine didn't have a tap. So, I drilled and tapped the cold pipe and put a hose barb fitting in there for the vac line.

My steup should be collecting oil in the catch can but I never found oil in the catch can.

On the other hand, the filter on the oil fil cap is always full of oil. I removed the filter and put the stock oil fill cap then put a small filter at the end of 3/8" hose and extended the hose to put that little filter underneath the stock filter location, far away from the engine. Now I see oil on the corner of my front bumper.

If the turbo is pulling blowby through the catch can, I should be collecting oil in the catch can not on that little vent filter.

Denali08

You know what I am thinking the reason to be, the turbo would pull all required air easly through the filter rather than from that little tap on the pre-turbo cold pipe. This is why engine vac will be much much more than what that little tap will see in front of the turbo with big filter competing with it.

TURBHOE

iTrader: (4)

this is why i said to install a venturi in the turbo inlet pipe. the air flowing past the venturi creates the vacuum not the suction of the turbo. its as easy as cuting a pipe fitting at an angle and installing it in the airway. the cut portion facing the turbo.

Noah Burns

iTrader: (5)

ok, so the consensus is that I should use the engine as the vaccum for the canister not the intake system. Some of my DoD Delete parts started coming in today. I noticed on the 4.8L valley tray there is a threaded bung on the back side. Would I be able to use that location, thread a fitting in there, run a 90* and a line to the canister that would be the "suction" line to pull from the can. If that port would work, would it require a check valve also, I wasn't sure on that location.

If that spot won't work I'm just going to use the stock port on the intake manifold and run a check valve int here.