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I have been seeing more and more forced induction builds done with the entire PCV systems functions being defeated, which will lead to premature engine failure period. The PCV system serves several purposes, and only one part is relieving crankcase pressure.

As part of the combustion process, several damaging compounds enter the crankcase as blow by, and if these compounds are not imediately evacuated while still in suspension, they quickly condense and fall into the engine oil accumulating with every start/stop cycle greatly accelerating engine wear.

These compounds consist of the following:

Water vapor released during the intense heat and pressure during the combustion process. While most exits out the exhaust, some enters the crankcase and mixes with other hydrocarbons to form Sulfuric acid. This begins to attack all metal surfaces and also causes corrosion.

Unburnt fuel. Dilutes the oil and reduces its ability to protect against wear and galling.

Abrasive soot and carbon particles. Much of these are to small to be trapped by an oil filter and once in the oil remain there circulating through the engine accelerating wear until the oil is changed.

And other various compounds.

Here is a good training video explaining this:


Filtered, fresh air must always be entering one side (the "Clean" or "Fresh" side of the PCV system) to make up for, and flush the dmaging compound laden "Foul", or "Dirty" Side of the crankcase. This must be maintained constantly to remove these compounds as soon as the enter the crankcase, or they will quickly settle and mix with the engine oil contaminating it as well as the water and sulfuric acid coating the parts in the upper portion of the engine wear they condense at every shut down.

Here is a picture of the rocker arms of a LS engine after only 6 months running this type of system:



IF you defeat all of this, and just vent pressure into a vented style catchcan, all your doing is releasing pressure and all evacuation and flushing has been effectively defeated. The vented/breathered can will capture some dirty water vapor and a small amount of oil mist that escapes with the pressure, but a fraction of what is accumulating in the engine.

As you could see in the video, on a naturally aspirated engine, the intake manifold provides this vacuum to maintain constant evacuation and removal of these compounds at all but hard throttle, but with any centrifugal super charger or turbo application, the intake manifold becomes pressurized quickly with boost, so a standard PCV design will not work. So you have to use a system that does proper evacuate at all times.

Here is how the RX system for forced induction works:

The dual valve RX system used for FI works by using the intake manifold vacuum for evacuation while at idle and non-boost operation as the OEM system will, but as soon as the primary valve detects any boost (or lack of vacuum present in the IM) closes so no pressure can enter the crankcase via the can and lines. The secondary valve will then open, using the suction (inlet) side of the SC head unit, or the turbo (same as GM does with the new Caddy ATS turbo) so there is uninterrupted evacuation taking place at all times, in boost or no boost. All vapors are drawn through the RX separator (no equal on the market in effectiveness) and all the oil mist & vapor, water vapor, unburnt fuel, etc. is removed from the crankcase vapors and only cleaned vapors enter the combustion process. The system remains emissions compliant (except the planet CA due to CARB cert requirements) as it stays closed, the crankcase evacuation is actually more complete than stock, nothing vents to the air causing smell and pollution, and the engine gets the chance to live a long life without the accelerated wear caused by leaving these compounds to accumulate in the crankcase.

Here is an example of what accumulates int he crankcase when you do defeat evacuation. This is a new Ford EcoBoost twin turbo with a PCV system that only evacuates at idle and non boost (remember, when you defeat the PCV system and use a vented tank there is ZERO evacuation ever taking place...the ecoboost at least evacuates at idle and low throttle):


The video above shows immediately after installing the RX system for forced induction as it pulls out what had been accumulating in the crankcase. After a thousand or so miles the mix caught is mainly oil and contaminates with far less water and unburnt fuel as this shows.

What this mix looks like when allowed to settle for several days:



Over time, this will settle into 4 separate layers with water and sulfuric acid on the bottom. Unburnt fuel next, then emulsified oil/water, and finally oil at the top. You do NOT want this accumulating in the engine of any vehicle, much less a $70k plus Stingray.

Even the most basic economy race car will at least have a basic inexpensive header evac venturi system, and most will have a belt driven vacuum pump, and these are cars only raced...not run daily on the street where you are throughout the day starting the engine, parking and cooling, etc. I cannot stress enough how critical these functions are, and as the wear is gradual over time, most wont see the results until it is to late 10-20k miles down the road from running a defeated PCV system. Even the most basic lawn mower engine has evacuation function.....so to see these advanced cars, with excellent designed FI systems making big power, not understand what defeating these critical functions does to the engines life.

Ask questions, please be detailed if anyone doubts this. I see expensive system being installed that totally defeat all evac function more and more with no thought to what your doing to your engine over time. This makes the intake valve coking issue look like nothing in comparison. So lets make this an intelligent Q&A thread so all understand every aspect of proper crankcase evacuation. I can show bearings and crank/cam journals showing the damage as these compounds have attacked them over time, etc.
 

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Tracy, thanks for the post. But I think here you are referring to someone slapping a supercharger on a naturally aspirated engine.

What about supercharged engines which come already supercharged from the factory? Surely they evacuate even under boost.

Assuming they do, my question would be how does a catch can for a supercharged engine differ from a catch can for a naturally aspirated engine? Please list all the differences. Also, some particular points I am wondering about include the following:
1) How does the catch can handle the added pressure? I assume there is more pressure in the PCV system on a supercharged system. Isn't that correct?
2) Where are one-way check valves required in the plumbing for a catch can in a boosted engine, and how does this differ from a naturally aspirated engine?
3) What other differences are there for catch cans on a boosted engine compared to a NA one?
4) What about clean side separators? Are they exactly the same for NA and boosted engines, or can boost blow pressure out the dry sump oil tank unless a check valve is used? Is this correct, or am I missing some things here?

Thank you for your time.
 

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Tracy, as you are aware I've order your complete system for the forced induction Z06 coming out in several months. I assume you will be providing me with everything I'll need for the Z06. There was one point you made in this thread that jumped out at me and became a concern. You mentioned "The System Remains Emissions Compliant Except The Planet CA" Due To "CARB Certification Requirements" as it stays closed. Being a California resident, am I going to encounter difficulty getting my Z06 SMOG Checked once I'm required to do so? And is the system going to work properly for a Z06 in California?
 

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Discussion Starter #4
Tracy, thanks for the post. But I think here you are referring to someone slapping a supercharger on a naturally aspirated engine.

What about supercharged engines which come already supercharged from the factory? Surely they evacuate even under boost.

Assuming they do, my question would be how does a catch can for a supercharged engine differ from a catch can for a naturally aspirated engine? Please list all the differences. Also, some particular points I am wondering
about include the following:

All good questions. To date, no GM vehicles comes stock with a centrifugal super charger, they are all positive displacement Eaton based units, so they replace the intake manifold with the lower plenum, and all vacuum is supplied at all operating levels by the inlet side circuits built into the unit, so your brake booster and other vacuum dependent systems always work and have vacuum. So, those systems on the CTS-V, ZL1, ZR1, all have a proper system that does evacuate at all times. These GM platforms also have a included clean-side separator between the valve covers and the air bridge (plastic cylinder). So only those FI applications that pressurize the intake manifold have the need for a special system like described. That will be turbo charged and centrifugal (basically a turbo driven by belt and gears VS exhaust gasses) super charged applications.

1) How does the catch can handle the added pressure? I assume there is more pressure in the PCV system on a supercharged system. Isn't that correct?

A properly designed system the catchcan should never have pressure in it. That is why it is critical to always have suction, or vacuum present from a source to constantly evacuate. Anything that allows pressure is detrimental in several ways from seal/oil leaks to the added windage that the pistons must fight to move downward in the cylinder bore. As laid out in great detail in the first post, that is why you use intake manifold vacuum to evacuate and pull vacuum at all non-boost operating levels, and the turbo/centri SC inlet for suction/vacuum when in boost. The higher the head unit spins, the more usable suction to ensure no crankcase pressure can build, and that the damaging compounds entering the crankcase as blow-by are always evacuated/removed from the crankcase immediately and not allowed to accumulate.

2) Where are one-way check valves required in the plumbing for a catch can in a boosted engine, and how does this differ from a naturally aspirated engine?

It is all explained in the first post, but here is more detail. The Stock GenV engine has a one way check valve already that comes off of the valley cover, pointing to the drivers side front. This helps prevent back flow, (RX has used these for app 13 years on all cans to prevent this, GM just started this year) but the design was never meant to deal with the boost pressures of turbo or centri SC, so when installing the first systems most made no provisions for this and it jammed the OEM check valve so it would not work. The RX uses a much stronger, oil/fuel/heat resistant inline unit that holds up to 20# boost plus, and zero failures out of thousands we have used. These both go inline from the RX oil separator (can) flowing away from the cans outlets, one in the primary outlet and one in the secondary. The primary allows vacuum from the intake manifold (when in non-boost operation) to evacuate the crankcase and as soon as vacuum is no longer present (when beginning to make boost), the primary valve closes (allows NO pressure back through) and prevents any boost pressure from entering the can, or crankcase from the IM. The hose we provide is good to 60PSI and most FI will never be above 20, so over engineered there. Then when this occurs, the secondary valve opens and utilizes the suction/vacuum provided by the FI head unit inlet to continue providing evacuation at all times, boost or no boost. With the RX system you leave the OEM valve intact, as it also regulates the CFM of flow and that is needed. The RX valves protect the OEM valve so it is never subject to any boost and can't therefore jam. So I think your misunderstanding what occurs with the system, and the difference in the types of forced induction.

3) What other differences are there for catch cans on a boosted engine compared to a NA one?

Proper valving, size, and effectiveness. NO can equals the RX in effectiveness, and independent testing (mostly by competitors taking the RX challenge) come near. The average can only traps 15-30% max...RX catches all, or nearly all (95-99%).


4) What about clean side separators? Are they exactly the same for NA and boosted engines, or can boost blow pressure out the dry sump oil tank unless a check valve is used? Is this correct, or am I missing some things here?

Thank you for your time.
Cleanside separators are only available from GM (very poor design, no coalescing material, etc.) RX and Elite. There should never be boost anywhere but between the head unit (turbo or centri SC), the intake pipe/intercooler, and the intake manifold. Again, these are all good questions, but somewhere your missing what ALL forced induction does. It pressurizes the intake air charge, not the crankcase, dry sump, catchcan (one designed for FI) You would never want the dry-sump or crankcase to have any pressure. That is what is causing so much of the issues the makers/installers of aftermarket FI system run into. Not a single one seems to understand proper crankcase evacuation. They all short cut it. This is not taught anywhere I know of anymore, and seems to be a lost art except the professional race crowd, and seeing all these done improperly with greatly shortened engine life the results is alarming.

Keep good questions like this coming! Nice and detailed and to the point. There is no thing as a "dumb" question if you are not sure the answer. Expensive investment for many, and when considering any mod of this caliper (FI), you need to not take it for granted a tech/shop/company understands all aspects. The shops I see making and installing these systems that defeat all evacuation are smart, talented people that have great reputations for making big power, doing quality builds, but almost all are ONLY thinking relieving crankcase pressure only, and not all the critical functions the PCV system provide to ensure long engine life. They are taking the technology of the 1920's-50's and employing it in the most basic form and are either not aware, or are ignoring it. A wore out engine (not just a component, the entire engine....every moving part is effected that is lubricated by engine oil) on a car like this is inexcusable. And the cost of changing oil every time you run it (only way to ensure proper oil properties over time if you defeat the PCV systems functions) far out weighs adding the proper type system. And the ONLY way to accomplish this aside from what I have described, is to add a belt driven vac pump system, which is the best solution, but the pumps will not live long enough.

Tracy, as you are aware I've order your complete system for the forced induction Z06 coming out in several months. I assume you will be providing me with everything I'll need for the Z06. There was one point you made in this thread that jumped out at me and became a concern. You mentioned "The System Remains Emissions Compliant Except The Planet CA" Due To "CARB Certification Requirements" as it stays closed. Being a California resident, am I going to encounter difficulty getting my Z06 SMOG Checked once I'm required to do so? And is the system going to work properly for a Z06 in California?
Have nearly 15,000 of these in use over more than 13 years, so you should have no issues. When installed, it looks OEM so have never had a visual inspection fail, (I assume some may remove it for inspection and re-install stock, but that is an assumption only. As it retains all emissions compliance in design and closed system, it will not trigger any readiness test failures from the electronic scanning. Your good.

Cheers!
 

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Hi Tracy,

Thank you for the detailed responses. Indeed, I am not very well versed in engine building, so I am sure some of my questions did seem foolish to you. For example, I did think forced induction would put added pressure in a crankcase, as I thought I heard some people were blowing out gaskets (I thought gaskets somewhere on the crankcase). As for asking about pressure in the PCV path, again I was under the impression the crankcase would be pressurized higher than the air outside the engine (higher than just the regular atmosphere under the hood), so I thought that the catch can would have to deal with higher than normal pressure when on a FI engine. By the way, if that path from the PCV valve through the catch can to either the IM or SC inlet are not pressurized higher than the outside world's air we breathe, then why do you use 60 PSI hoses?

Finally, yes, I did read your first post before asking all my questions, but I didn't understand, so that is why I asked. At any rate, thanks for taking the time to respond and give more details. Maybe if you have time to respond to my last paragraph above, hopefully I can put the final pieces of the puzzle together in my mind and understand clearly.

Thanks again,

-Rodney
 

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Discussion Starter #6
Hi Tracy,

Thank you for the detailed responses. Indeed, I am not very well versed in engine building, so I am sure some of my questions did seem foolish to you. For example, I did think forced induction would put added pressure in a crankcase, as I thought I heard some people were blowing out gaskets (I thought gaskets somewhere on the crankcase). As for asking about pressure in the PCV path, again I was under the impression the crankcase would be pressurized higher than the air outside the engine (higher than just the regular atmosphere under the hood), so I thought that the catch can would have to deal with higher than normal pressure when on a FI engine. By the way, if that path from the PCV valve through the catch can to either the IM or SC inlet are not pressurized higher than the outside world's air we breathe, then why do you use 60 PSI hoses?

Finally, yes, I did read your first post before asking all my questions, but I didn't understand, so that is why I asked. At any rate, thanks for taking the time to respond and give more details. Maybe if you have time to respond to my last paragraph above, hopefully I can put the final pieces of the puzzle together in my mind and understand clearly.

Thanks again,

-Rodney

Excellent Rodney.

All engines have a certain amount of blow-by. This is pressure that does escape past the piston ring/cylinder wall seal, and this must be dealt with. The stock PCV system does this by using the intake manifold vacuum so the pressure never builds. The seals you are correct are to seal the oil into the crankcase and keep dirt/dust from being drawn into the crankcase when under vacuum. Ideally there will never be any pressure that can be measured, as the PCV system evacuates and pulls suction/vacuum on it to remove not only the contaminates from the combustion process, but the pressure that is part off the blow-by. This should not be confused with boost pressure, which is never placed into the crankcase....that is always contained in the intake tract and is separate from the crankcase (where I think the confusion was). The only connection between the intake tract and the crankcase is the PCV dirty side line that runs between the IM and the crankcase PCV valve, and this is where the catchcans connect in-line between this, so thus the need for a strong hose as it will be under boost pressure from FI, but that is only in that short run of hose. The checkvalves prevent it ever reaching the catchcan (unless a typical catchcan where no checkvalves are used is installed on a FI application, then there will be).

Now, when you add FI you are increasing slightly the amount of blow-by, and this must be dealt with. The early C7's (the first year GM has included a checkvalve on the valley cover PCV vent) that vendors/shops were installing FI on they were not taking this OEM valve into consideration, so it would stick closed from the boost (it was never designed to see anything above a slight pressure) and then the blow-by had no way to be dealt with and pressure would eventually build and cause seal failures/oil leakage. But that was from not understanding the OEM system and how it worked. These vendors assumed it was like the previous GenIII and Gen IV LS engines so they never took the time to get educated (and most still are not...they just remove the OEM valve, which effects the amount of flow so it can pull excess oil and vapors in that it would not normally used as designed) and understand the changes before releasing these....and since so few tuner shops understand it, they just look at the obvious, and vent this to the air through a breathered can (illegal in all 50 states as well as a guaranteed way to shorten engine life) not realizing what this does to the engine oil and the engine over time.

So, an engine should never (or rarely ever) have pressure greater than the outside in it. If it does there are problems. They should with a proper system always have a slight vacuum as long as the PCV system is working correctly, or with a FI application the proper type of modified system. Unless it is a vented style I am warning about. These always have some pressure as they are never evacuating, only letting pressure escape as it builds through the breathers/vents.

I think I am on the right path to understanding your thinking. Your looking at issues others experienced early on with the FI builds? And to date, the ECS system we saw had the fresh, or cleanside line going into the un-filtered section of the airbox allowing completely unfiltered air along with dust, dirt, etc. to be sucked right into the engine. I sent them a detailed email explaining it, and how to simply relocate it to the filtered section but as always, they never replied (which is typical with most all vendors of FI systems...not a single one on the market I know of deals with crankcase evacuation and the PCV system correctly even though they have great quality products).

Let me know if this clears it up...and good contributions. This is an example of the lack of proper understanding out there in general.
 

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Thanks, Tracy. Yes, I think I understand it clearly now.
 

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Discussion Starter #8
Cool! We need more interaction in this discussion. Ask questions all so everyone understands every aspect of this.
 

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Hi Tracy,
I haven't got my 2015 C7 yet, but I have already been talking to Procharger about putting on their package for the C7.
My issue is that I see your points, but can I ask how can I deal with this issue if I use a Procharger? I have to be honest, are you selling superchargers or kits to get rid of this problem. I have reread the post a number of times but still don't understand. I am going to install the Procharger after about 1500 miles, but I want to make sure that I don't smoke the motor. (Cuz-then I would have to remove the supercharge and tell GM that their car broke! :) )
 

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Hi Tracy,
I haven't got my 2015 C7 yet, but I have already been talking to Procharger about putting on their package for the C7.
My issue is that I see your points, but can I ask how can I deal with this issue if I use a Procharger? I have to be honest, are you selling superchargers or kits to get rid of this problem. I have reread the post a number of times but still don't understand. I am going to install the Procharger after about 1500 miles, but I want to make sure that I don't smoke the motor. (Cuz-then I would have to remove the supercharge and tell GM that their car broke! :) )
It might be a little late to take that option since you now have publicly put GM on notice...
 

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It might be a little late to take that option since you now have publicly put GM on notice...
True! All need to realize every good sized forum the auto makers are on and reading.

We have reached out to Procharger to share the issue and how to prevent it now all GM V8's are, or will be DI, but just as A&A and others, they seem to think there is no difference. I will guarantee this is needed, and just ask details on any part you may not be clear on and I can help.

NO supercharger company is configuring for proper crankcase evacuation currently, and only a handful of turbo system companies are.

Cheers!
 

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It might be a little late to take that option since you now have publicly put GM on notice...
Ooops- But my name is not Davem. It is John, John Wayne. :)
 

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A couple more questions for you.

1. Do you have a system that would work with the Pro-charger?
2. Can I look at the system on your website?
3. (I don't know if it is appropriate to ask here) but what does your system cost?
 

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Yes we do. Procharger, Paxton, or Vortech based take the dual valve system plus cleanside separator.

Here is what it looks like:

http://www.stingrayforums.com/forum...-oil-ingestion-issues-direct-injection-7.html

Pretty straight forward to install. $299 plus $99 for the cleanside separator so $398 total (S&H is free here for members).

Call direct to order, or WeaponX is a dealer as well, just as quick to purchase from them and they know how to install as well.

If in FL, we will install at no charge just to document intake valve coking rates at different miles.

Cheers!!
 

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Thanks,

Once I get my 2015, the fun will begin.
 

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I have your rx dual valve can and clean side on my z51 I was talking to lashway about a super charger and he wants me to put in his crankcase vent and remove the catch can, do you think your setup I have relieves the preasure during boost he said he has had seals blow out on these motors and thats why they use there venting system, I know the problems deleting the pcv , would 1000 mile oil changes remove contaminated oil quik enough with his set up or am I fine with your setup relieving preasure on seals?
 

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I have your rx dual valve can and clean side on my z51 I was talking to lashway about a super charger and he wants me to put in his crankcase vent and remove the catch can, do you think your setup I have relieves the preasure during boost he said he has had seals blow out on these motors and thats why they use there venting system, I know the problems deleting the pcv , would 1000 mile oil changes remove contaminated oil quik enough with his set up or am I fine with your setup relieving preasure on seals?
Marc,

Per our conversation, I recommended that you either ADD another RX can to your system at 550+ RWHP, or remove the can all together and opt for our breather tank which has been tested on 600+ RWHP vehicles now for some time with great results.

We have no negative feedback regarding the RX cans, and have seen their benefits. At the end of the day, you need to decide (based on your research and our professional opinion) which will work best.

The issue we have seen with single can set ups on big power cars is their "bottleneck" effect at a certain point with respect to the pressure being able to move through the smaller lines, into the can, out of the can, and back into the intake.

Our tanks have much larger lines, and larger volume and are able to move the specific amount of crankcase pressures we typically see on boosted engines. Of course a naturally aspirated engine will have different requirements.

Again, we recommend that you either add a can, one per bank, or a breather tank.

If we can be of any more assistance, let us know!

[email protected]
 
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