EFIDynoTuning Forum

Hi Michael.
It looks like you lost all of the archives.
I'd like to resurrect the topic of using a closed pcv system with boost. I had our discussion bookmarked because I have the memory of an earthworm.

In your pre tune info; you say this:

"The PCV system MUST be completely sealed. For boosted engines, a check valve is required to be installed between the valve cover breather and the inlet/suction side of the turbo/supercharger. The check valve must be mounted in reverse so under non-boosted conditions, the PCV will evacuate the crankcase and suck the check valve shut. Use only PCV valves that have internal checks and will lock to prevent backflow or bleeding of boost pressure into the crankcase. With this configuration, during boosted conditions, the manifold reference PCV valve will lock and the check valve on the breather line will open from the inlet vacuum to evacuate the crankcase. For race engines, it will be necessary to install a catch can to prevent oil from entering the intake. For more details see THIS THREAD."

I believe the thread linked at the end was the discussion I started previously about this topic. Hopefully this link can be restored for all users after we discuss this again.

In your above scenario; wouldn't there need to be a check valve in the hose between the upper intake and pcv? The check valve would be inserted backwards so the direction of flow is from the pcv back to the upper intake to prevent boost from entering the crankcase. In my case; I'd like to use a separator between the upper intake and pcv as well.

Also; would an oil catch device be needed in the hose leading from the oil fill nipple to pre turbo fitting?

Could the pre turbo fitting actually be located into the intake tubing as another alternative?

Thanks!
Eric

Here's a drawing I came across:

You already have a check valve on the pcv itself. I.e. Use only PCV valves that have internal checks.

You can put a catch can on the inlet if you'd like as well no biggie.

Yes pre-turbo fitting would be on the inlet piping between the turbo and air filter.

My rigged setup.. works like it should

decipha wrote: ↑2021 May 18, 17:50 You already have a check valve on the pcv itself. I.e. Use only PCV valves that have internal checks.

You can put a catch can on the inlet if you'd like as well no biggie.

Yes pre-turbo fitting would be on the inlet piping between the turbo and air filter.

I believe I have a turbo coupe pcv. I bought it a year ago and I've slept since then. Lol.
Thanks!

034v wrote: ↑2021 May 19, 09:26 My rigged setup.. works like it should

Thanks for the detailed pic. How well does that air compressor separator work at catching oil and moisture?
You're running a check valve between intake and pcv?

Fasterthangas wrote: ↑2021 May 19, 12:55

034v wrote: ↑2021 May 19, 09:26 My rigged setup.. works like it should

Thanks for the detailed pic. How well does that air compressor separator work at catching oil and moisture?
You're running a check valve between intake and pcv?

works good so far. yes running a check downstream of the catch.

034v wrote: ↑2021 May 19, 09:26 My rigged setup.. works like it should

I just thought of something. Shouldn't there be a check valve between the oil fill tube and turbo inlet. The direction of flow would be from the turbo back to the oil fill.

Also; is the turbo always pulling a vacuum on the oil fill tube? If the oil fill tube is able to draw air in from the turbo; it would be unmetered air. No?

Fasterthangas wrote: ↑2021 May 27, 17:23

034v wrote: ↑2021 May 19, 09:26 My rigged setup.. works like it should

I just thought of something. Shouldn't there be a check valve between the oil fill tube and turbo inlet. The direction of flow would be from the turbo back to the oil fill.

Also; is the turbo always pulling a vacuum on the oil fill tube? If the oil fill tube is able to draw air in from the turbo; it would be unmetered air. No?

In a N/A vehicle the suction is always there. It mostly for fume reclaim and crankcase venting when at high loads anyways. No check needed on the VC side. Depending on how your MAF is configured will determine sampling un-metered air or not. Draw thru, no. Blow thru it could but most strategies have an un-metered air scalar that can be set to ignore minor leakage.

Mine is a tuned speed density ECU so..

034v wrote: ↑2021 May 27, 17:29

Fasterthangas wrote: ↑2021 May 27, 17:23

034v wrote: ↑2021 May 19, 09:26 My rigged setup.. works like it should

I just thought of something. Shouldn't there be a check valve between the oil fill tube and turbo inlet. The direction of flow would be from the turbo back to the oil fill.

Also; is the turbo always pulling a vacuum on the oil fill tube? If the oil fill tube is able to draw air in from the turbo; it would be unmetered air. No?

In a N/A vehicle the suction is always there. It mostly for fume reclaim and crankcase venting when at high loads anyways. No check needed on the VC side. Depending on how your MAF is configured will determine sampling un-metered air or not. Draw thru, no. Blow thru it could but most strategies have an un-metered air scalar that can be set to ignore minor leakage.

Mine is a tuned speed density ECU so..

I'm running boost so definitely not n/a.
If unmetered air can be accounted for in the tune; I can run a breather on the oil fill tube. No?
I need a closed pcv system. If the system is drawing in unmetered air; it's an open system.