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You can't just block off both connections, the engine blow by has to go somewhere or it'll cause lots of problems especially on a turbocharged engine
No, you have to plug the connections on the turbo housing and the intake tube. The crankcase then vents to the atmosphere. If you don't plug those two points it will be like having a massive vacuum leak.
 

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I planned on pulling the intercooler anyway to get all the oil out of it and I'm hoping no pieces of the impeller traveling at high velocity damaged it. Definitely want to do a PCV disconnect from the turbo. My car only has 38,000 miles so I guess repeated 25 psi runs aren't a good idea with the stock Borg Warner turbo.
 

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bearings went bad. You had too much end play in the shaft and it finally came into contact with the intake bore. It took a chunk out of one of the blades which threw it out of balance which caused the rest of the carnage. I know this because the hole that the shaft goes into on the compressor wheel is no longer round.

Oh a turbo can literally turn into a grenade.

Motor vehicle Gas Auto part Automotive wheel system Automotive tire


well, dig a hole in your back yard and lay that one to rest. there is no fixing your turbo.
 

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If you plug the 2 openings on your valve cover you will have an oil version of Old Faithful coming out of your dipstick tube..
 

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The ONLY way to remove the turbo from the PCV system is you have to remove the intake manifold and take the PCV valve out of it. Plug that hole. Then take the hoses off of the valve cover and plug the turbo side and the intake pipe side of those hoses. The 2 connections where you took the lines off the valve cover you have to add breather filters to.

That is the ONLY way it can be done.
 

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The limit to the stock BorgWarner turbo is 22 PSI with peaking to 23 PSI. anything above that is just doing damage to it.
 

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It does get expensive, I'm going to get a better turbo from PAW. I'm thinking either the ZZP or the WR3. My finances are a little shaky after spending $650 on a new water heater, supply lines, shut off valve and insulation blanket. Probably going with the ZZP.
 

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The ONLY way to remove the turbo from the PCV system is you have to remove the intake manifold and take the PCV valve out of it. Plug that hole. Then take the hoses off of the valve cover and plug the turbo side and the intake pipe side of those hoses. The 2 connections where you took the lines off the valve cover you have to add breather filters to.

That is the ONLY way it can be done.

Help me understand something because I am definitely ignorant on this system compared to most others and your responses are very detailed so I might be able to get a grip.

Normally there is a vacuum at the turbo port which draws crank case gases out through the tube in the cam cover and into the intake & cylinders where it gets burned. These gases are blow-by and the air which is drawn into the crankcase through the other hose connected to the intake tube.

Question, what happens at the turbo port while under boost? Is it still under vacuum or is there positive pressure there? Does the flow reverse itself under boost or stay flowing in the same direction?
 

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OK the solstice GXP has 2 PCV systems This is because when the engine is under boost there is no vacuum inside the engine so the typical PCV system will not function. The only place that has a vacuum when the engine is under boost is directly in front of the turbo inlet which is where one line is attach and that line runs to the valve cover. The second line that is attached to the valve cover is a vent. In order to have air circulation there has to be air going in and that is what the vent provides. The vent is attached to the intake pipe 1/2 way down the intake pipe. When the engine is not under boost the PCV line that runs between the turbo and the valve cover doesn't do anything. There are still blow-by gasses and oil gasses that need to be collected and burned when he car is not under boost and that leads me to the second PCV system. The second system is built into the intake manifold and it requires taking the intake manifold off the vehicle in order to access the PCV valve. The PCV valve is inside the intake manifold literally. There is a passage that runs through the cylinder head and goes into the crank case when the car is not under boost there is a vacuum in the intake manifold that vacuum causes the higher pressure from the crankcase to want to move up that passage and into the intake manifold. The PCV valve is a check valve and will only open when the intake manifold is under a vacuum and not boost. Again there has to be air in in order to have circulation so the vent on the valve cover works for both PCV systems.

So if you want to eliminate the PCV system going to the turbo you MUST also delete the one in the intake manifold as well. This is because of the entry of air that has not been measured when the engine is NOT under boost. You have to block off the intake PCV to stop that from happening.


The reason why there is an issue with the design of the LNF is not because of the PCV system in and of itself. The problem is due to the design of the PCV system and also the BPV system. The BPV system takes the pressurized air from the output side of the turbo and recirculates it back into the intake side and the location of where the air gets put back into the intake side is directly across from where the PCV line attaches to the turbo. So if you are at 14PSI of boost and when you let off the accelerator the BPV dumps the excess pressure and what was a vacuum in front of the turbo now becomes a positive air pressure and that pressure blows up the PCV line and into the valve cover where it makes its way to the vent and then down the vent line and into the intake pipe. The problem is the valve cover is not baffled on the vent so oil from inside the valve cover gets carried into the line. Now there is check valve on the vent line but it is of cheap construction and is not designed to handle that kind of pressure and it is not designed in a manner that would keep it from gumming up and getting stuck open. When that happens oil gets blown into the intake pipe and ends up getting into the intake manifold and onto the backs of the intake valves.

The issue is the piping and CAC volume between the turbo and the throttle body is exponentially larger then the area inside the intake pipe. so when the BPV activates and the pressure gets dumped it is going to go anywhere it possibly can and that includes up into the valve cover.


If you think about it it is really not a good design because that pressure once it gets into the valve cover ends up pressurizing the entire crank case and that pressure then pushes up into the intake PCV system bypassing the throttle body. This is why I believe there is a god awful amount of rev hang. Not all of the rev hang is intentional. If the air has a way to get into the engine and bypass the throttle body you are going to see the rev hang. GM knows that this was happening so the ECM has been programmed to handle it by shooting more fuel when the accelerator gets released and the car is under boost. That additional air and fuel would be the same as holding the accelerator down for a second until the excess boost pressure dissipates.

When I have looked at the log files for my car I noticed a larger rev hang when under boost then what is seen when the car is not under boost. That is the only thing I could come up with for that behavior.
 

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If you have the clutch pushed in and your rev the engine it hangs . It doesn't come back down when you let off the accelerator. It takes a second before it starts dropping. That is rev hang. The hang you se when doing that without the turbo spooled is by design. It is done to make it easier to drive and to improve the efficiency. Personally I find it to be exceedingly annoying.
 

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Having a turbo is good for making hp and toque and relatively straight forward functionally, GM's pcv system isn't very well thought out. When you feed just blowby by itself into the intake everything's good and most all automakers use the same system. It's when you have pressurized air pushing oil through the intercooler and into the intake is when you have problems. Excessive oil consumption, oil pooled in the bottom of the intercooler, excess oil coming into the intake and getting deposited on the valve stems inside the head. Heated to high temps the oil turns into carbon and carbon buildup can cause spark knock, the buildup can disrupt the airflow into the combustion chamber, and you also get carbon buildup on the pistons which again can cause spark knock aka pre detonation which is really hard on a engine, the ECU tries to control pre detonation through the use of knock sensors and retards the ignition timing to combat the knock. Using higher octane is one way to help control knock which is one of the reasons why the gxp has to have premium gas. Forced induction by nature increases the compression ratio, the higher the compression ratio the higher the octane level required. Back in the 1960's into the early 1970's high performance engine's routinely ran at 10.1-12.1 and higher compression ratio's so premium fuel was anywhere from 97-101 octane. Starting in 1972-1973 compression ratio's dropped as low as 7.5 to 1, averaging 8.5 to 1, that's when the use of so-called smog pumps came into being, injecting air into the exhaust manifold in a attempt to lower emissions. This is way before catalytic converters and 02 sensors. Luckily the old high performance engines only have to pass a tailpipe emissions test which they will if tuned properly. Then catalytic converters came into being along with 02 sensors and ECM's to control all the engines functions including emissions. In most ECM'S if the cat's efficiency drops to 95% you get a CEL fault code, p0420 I think, and the car can't be tested if you have a CEL on even though at 95% efficiency drop in the cat a tailpipe test would pass. So here's what you do to pass, get a spacer that will pull your downstream 02 sensor out of the exhaust stream and your car will pass with flying colors. For legal purposes this is a hypothetical discussion and I'm not advocating breaking federal emissions laws.😁
 
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