[redlinepontiac]

so im looking to see what people have done for a turbo pcv system. do you leave the stock valve in the valley pan and just run 10AN fittings on the valve covers to a breather tank? or something else?

[Tom Vaught]

A normal PCV system works like this:
Air enters a breather (either open to atmosphere or connected to the air cleaner in some manner). From the breather the air travels to the oil pan area. The engine is trying to remove corrosive gases in the oil pan and burn them in the engine so the air from the breather is "Make-Up Air" in the Crankcase Ventilation system.
A Normal PCV Valve, if it senses a Pressure in the intake manifold) CLOSES (because the PCV Valve actually is built with a "ANTI-BACKFIRE" function built into it. You do not want a explosion in the intake entering the oil pan.

So at some point Boost Pressure will try to close the PCV Valve (just like with a back fire).

That being said, the Shuttle Valve (inside the PCV Valve) is not a perfect seal and you will have higher oil pan pressure when under boost, BUT if you have a "Catch Can" after the valve cover and before the fumes are introduced into the atmosphere (or air cleaner box) you should catch most of the oil in the air going to the catch can and be fine.

Now if your engine has blow-by before you boost it with a Boosting device, nothing is going to keep the catch can from quickly filling with oil.

I have seen systems where a guy added a second PCV valve under the catch can and ran it above the oil level in the pan.
If oil collects in the catch can it drains back into the pan over time. Marty Palbykin, if I remember right, had one of those deals on his Grand Prix Street Car engine or a early boosted race engine.

Tom V.

[redlinepontiac]

thanks for the repsonse tom

i only asked that becuase i had seen an article in hot rod where they pro charged a 4.8 in a chevelle. and they had used the 2 fittings off the valve covers but also had the fitting in the valley pan routed to an oil/air seperator that fed into the breather also

[Tom Vaught]

Can you post up the link to the HR article.

Tom V.

[redlinepontiac]

http://www.hotrod.com/articles/venti...haft-pressure/

tom here is the article, what are your thoughts on how they have theirs?

[Tom Vaught]

1) Hey there are lots of LS Engines out there to replace the one he currently has and Hot Rod has lots of money to buy engines. Corrosive Gases in the crankcase killed the Model A and Model T engines in short order. Road draft systems and PCV systems were designed specifically to remove those corrosive gases.

2)You do not need more than 3 cfm of air flow in the crankcase to get rid of the corrosive gas. A boosted engine might be moving 1000 cfm thru the intake under boost.

3) When the engine is "Off Boost" and the rings are sealing properly in the bores you will have very little "blow-by" in the crankcase.

4) The fact that he is pushing a lot of oil out of the engine says the ring seal is marginal at best.

5)He posted that under Boost that the PCV Valve was shut, and I agree with that, so where is the pressure coming from to pressurize the crankcase and push out all of the oil film on the paint of the engine compartment?

6) PCV Valves do not seal perfectly but they are close in sealing. We are talking maybe .5 CFM of air from the crankcase past the PCV valve when under boost. Maybe .5 to 1 psi of pressure in the crankcase with a boosted engine. He has other issues.

7) Putting a Collection Tank and a Oil separator on on the engine (to collect the oil being pushed out of the engine) is not the way to fix a ring seal issue.

Ford Has sold over 2 million Turbocharged EcoBoost engines that use normal pcv type systems and do not push massive amounts of oil
out of the engine crancase. If you do not like reading about Ford Engines then read about the new 2018 Boosted High Output Corvette Engine and copy that system on your LS or Pontiac Engine.

So he is trying to fix the wrong issue.

Tom V.

[RUDOLFSSON]

This is what I came up with some years ago..... regular breathers on the valve covers into a catch can.
a single line from the catch can into the exhaust (engine/transmission area) with the old school moroso evac 45° type of a deal...

The catch can seems to catch the moist that otherwise will build up on the inside of your valvecovers... Covers are baffled and the inside of the catch can too... I've never seen any oil into the can but maybe half way into the lines..

I have a vac. gauge hooked up to the can... can't remember how the reading was though ... LOL



Kris.

[redlinepontiac]

thanks kris, i may just follow that path. do you still the stock pcv in place?