Hello to anyone that can help.

Crank Case pressure is whopping my assets#$#. I have an stroked LS7 (441) and it's equipped with Vortex TI trim V2 supercharger. right now the supercharger is creating soo much crankcase pressure that it preventing the supercharger from draining properly and forcing the oil back up through the seals. It's soo bad that its blowing through the intercooler. I thought the seals were bad in the supercharger but the unit doesn't even have 40 miles on it. I'm know at my wits end trying to figure out how to vent this crank case if anyone has an LS7 with Ti trim V2 please send pics on how your return oil line is routed and advise you can provide would be greatly appreciative.

 

If you have that much crankcase pressure you might want to stay out of boost until you get that resolved or you could end up blowing out the front or rear main seal.

Do you have a catch can on your car? If not that would be the first thing I would do. Need to get a vented catch can. I run the Mighty Mouse can that vents to the atmosphere. I have run two -10 lines (welded fittings to the valve covers) to the catch can . Can is mounted in the passenger front fog light area directly above the brake ventilation intake so that it can be easily drained when needed.

 

Thanks for the advice. I already started pulling the supercharger today thinking the same thing. The engine is brand new so I'm thinking the rings also needs time to seat properly. I figured I would run it naturally aspirated for a while.

 

If you’re getting that much blowby, just taking the blower off and running it naturally aspirated won’t solve the problem, since crankcase pressure isn’t caused by boost, but by air leaking past the rings. I agree completely that you should get a Mighty Mouse vented catch can, which will use vacuum to pull the air out of the crankcase during idle/cruise, and a filtered pressure relief to let any crankcase pressure escape during WOT.
At the very least, get yourself one of David’s filtered pressure relief valves which replaces the oil fill in the valve cover:
https://www.mightymousesolutions.com...ll-an-adapters
It’ll be the best bang-for-the-buck investment you’ve ever made on your car, IMV.

 

Either motor is hosed, or you PCV/Venting system is messed up so you are pushing boost into the crank case. Either way, need to get it fixed. Make sure you don't have any pressurized lines to the crank case, and if they are needed, have a 1 way check valve.

 

Good point ....

 

It just needs proper PCV setup and to have no broken or damaged piston rings.
I would not use a catch can, that is for broken engines or very very high output situations (over 1k rwhp @ 6L+)

Anytime you run forced induction you should also monitor crankcase pressure, use a 2-bar map sensor and data log the pressure.
You want approx 2 to 4" Hg of vacuum in the crankcase at all times. This is accomplished using the correct orifice diameter and pcv hose route.

The pre-compressor (post air filter) tube should feed the fresh air vent of the crankcase. There should never be any breather on the crankcase; all of the air should come from the pre-turbo (pre compressor) inlet, which is post air filter. The air filter provides the pressure drop which drives the crankcase pcv during WOT; this means your air filter has the final say in the pressure drop achieved by the crank case pcv.

The other side of the pcv system is for idle/cruise only, and it needs to incorporate a high quality pcv valve. I use a SUPRA TT pcv valve *only*. Never use the OEM chevrolet pcv valve for forced induction they are leaking bastards.

So there should be 1 hose from a valve cover, through pcv valve, to the intake manifold (idle cruise side)
And 1 hose from the other valve cover, to the post air filter, pre compressor tube (WOT pcv side)
And a 2-bar map sensor with data logger placed on the valve cover near the WOT side.
Adjust orifice diameters and air filter to achieve approx 2 to 4" Hg pressure drop (a couple psi of vacuum) during boost.

 

Not to hijack thread, but may as well get info where the guys are already talking about PVC/Venting issues

ls3 wet sump/f1a94 procharger

I have 2 10AN lines to vented catch can (one from each valve cover)

pcv port on valley cover looped to the port on (3/8 hose) the pass side port of intake manifold----Am I boosting the CC since there isnt a check valve in the little loop?

 

Intake manifold would be pressurized under boost. That means you are just pumping boost from your intake manifold right into the PCV port on valley.

 

ok
In your opinion, should i run a sealed catch can with a ck valve, or vented catch can w/ck valve between those two ports?

 

I run a -10 from each valve cover to a vented can and a check valve on the 3/8 hose from the valley to the intake. Never had an issue set up like this.

 

Do whatever you want, but pumping boost right into the bottom of your motor is bad. Either plug those ports, or run a checkvalve.

I run -10 off each cover, and then a seperate one on the back of the ICT billet lifter plate cover to can.

 

Combustion pressure is 1000psi~ so by running a vent/can setup you are still essentially boosting the crank case. There is no 'proper' way to setup a vented crankcase, because it will always be under pressure when in boost, since some of that 1000psi is going to leak into the crankcase and there is no suction to remove it. If you put a 2-bar map sensor on the crankcase and monitor the pressure you will see in the most healthy engines around 2psi of boost in the crankcase when using a vented/can setup. 2psi of pressure is enough to cause oil leaks and reduce piston ring function- it is NOT the right way to setup a "PCV" system since the word PCV literally means having less than 0psi in the crankcase at all times. These people running cans/breathers simply don't know any better, they just copy each other and fail to recognize the detriment this type of setup causes over time (reduced ring function and oil leaks), and have never monitored their crankcase pressure properly so they have no clue what is happening in there.

 

Here is an example of somebody monitoring their crankcase pressure with a 2-bar map sensor at 800rwhp.
Notice his PCV system is "vented" , there is no actual PCV (pressure is above 0psi at all times in boost) even though there is a check valve to prevent boosting the crankcase- it still sees 2psi of boost.
Therefore the pcv system is still not setup properly. But at least he is finally monitoring the crankcase pressure and becoming aware of the effects of running a pure breather/vent.

Imagine you hook an air compressor to the crankcase and set it to 2psi and walk away. how long do you think it will take before an oil drip develops at the front and rearm mains? And how does that pressure affect the piston ring function when the engine is running? Gasses need to be able to get out of the space between 1st and 2nd ring and they do so by 'fleeing' to the crankcase, but when the pressure rises in the crankcase this slows down that effort and reduces the piston ring seal function. It also alters the oil control ability of the rings and puts additional pressure on all oil seals.

All turbo cars from the factory incorporate an actual, active PCV suction for the crankcase during boost which ties the pre-compressor inlet to the crankcase in order to improve ring function and reduce oil seal issues.

 

This might be the only thing King has ever posted that we're on the same side on.

I got rid of my catch can altogether. Basically hooked everything up like his earlier post has it (did it years ago). No more smells, no more draining catch cans.

I used a check valve between the valley cover port and post TB port so it "sucks" on the crankcase outside of boost and does nothing there once in boost. Valve cover connected to air filter pre-blower so blow by will get sucked through there once in boost. Whether it's enough to keep up or not.. not sure. I haven't had any oil leaks and it's been that way for probably 40K miles so probably it's fine. I doubt I'll get bored enough to throw a sensor on it any time soon but would be interesting to know. This is a stock bottom end setup... looser rings would probably need more venting/vacuum/whatever you want to call it to keep up.

 

Well, as much as I appreciate the sentiment,

Its more like we both agree that the factory got it right. This method is simply original equipment by design; the OEM pcv setup is ideal, simple, works great, proven for 25+ years on turbo applications already. It hasn't changed from 1989~

Toyota and Nissan have been using this method since 1989~ to keep their 2jz-gte and RB26DETT etc... turbo engines leak free and facilitate high mileage (200,000+ miles) with cast aluminum pistons and high boost pressure (high power/displacement ratios)

Lets do a little compare,
A typical 3L Toyota 2jz-gte (1998-2002 'vvti') will support roughly 800rwhp in a daily driver application on Alcohol with cast factory aluminum pistons 8.5:1 compression ratio.
The 2.6L Nissan RB26 series will support the same power/displacement @ (800/3*2.6) = 693rwhp lets say 700rwhp with 2.6L, same compression and piston casting material

If we extrapolate that data then,
A 6L Chevrolet engine should support around (800/3*6) = 1600rwhp using the same compression ratio, cast piston, etc...
However we must account for:
increased compression ratio, lack of piston oil squirters, reduced RPM Redline potential, increased rotating mass (fringe piston velocity and rotating component kinetic and momentum impose rate of change energy limitations)
Thus, knock off say 5% potential for 9.2:1 an average compression ratio (more compression means less tolerance to max boost with full timing), another 8 to 12% for power loss due to aux piston cooling (i.e. water injection) and finally to account for redline and momentum energy we have to look at torque,

The factory 3L @ 800rwhp working backwards at 8,000rpm (near factory redline of those engines RB/2j which utilize solid lifters from the factory) is:
525ft*lbs*8000/5252 = 800
so, those 3L daily drivers are producing roughly 525ft*lbs of torque max (to maintain reliability this is a rough 'safe' limit),
which means the 6L all else equal will be safe up to around 1000ft*lbs of torque, using that at a reasonable redline for 6L factory internals:
1000*6,800/5252 = 1300rwhp
now lose the compression and 'water injection' safety headroom, ('water injection' implies any/all kinds of injections: methanol, nitrous, water, other fuels, butter, etc... )
1300 * (1 - .05 - .10) = 1105rwhp safely using water injection to limit EGT on alcohol fuel with a cast piston application at 6L (04-07 chevrolet 6L Truck engines)


lets do a "Take aways":.
A. anybody at ~6L and 1100rwhp (or 2L at 1600/6*2=533rwhp, or a 3L at 1600/6*3=800, or 4L at 800/3*4=1066rwhp etc...) should not be using any catch can, as a general rule, verify (2barmap) a working factory turbo PCV setup
B. the target max pressure is 2 to 3" of Mercury, this number is a MAX setting range. I am not saying to set the pressure that low I am giving a safe max. The actual pressure you shoot for depends on the application and engine installation and intentions. For example in OEM applications a brand new filter target 0.5" Hg perhaps, but as it gets dirty this will increase to 1.5 to 2.5"Hg with say 500 miles of driving in some typical OEM vehicle. Eventually it will 3" 4" 5" as the filter gets more and more clogged because air pressure differential across the filter surface area is increasing as the air filter clogs naturally in an OEM installation, paper is highly effective filter materials and they tend to wear out quickly and need total replacement. So notice the OEM doesn't really have a target; it starts near atmospheric and gradually drifts as the car daily drives and the air filter clogs and more vacuum present behind the filter pulls harder on the crankcase over time. This design means that the worse off the filter is, the more crankcase vapors the engine will consume. It helps to counter the effects of aging, as lower pressure is helping keep oil out seals. It's a self cleaning feature which also protects engine oil as the filter maintenance starts lacking. If the guy isn't changing the air filter then they probably aren't changing the oil filter either, so in order to keep the oil cleaner there is more vacuum when the filter is more clogged and in need of maintenance. In other words they are saacrificing power for engine cleanliness because the guy isn't maintaining the engine and what you wa nt from a manufacturer is for them to design an engine to slow down its useage of engine oil when it is being neglected. It's a machine-self preservation technique, if the engine had their own minds they would want a nice pcv suction present to preserve their liquids butt hey cannot tell us this directly. Instead it shows up as a learning experience over the years if you are unaware of this highest of high concepts for combustion engine maintenance and care. The highest quality engine deserves the highest attention to it's crankcase pressure over all other pressure save oil pressurefor that is the heart worthy of slightly more recognition, and they are tied together the oil system and pcv systems are both part of each other and cannot function completely perfectly without each other.

So for another example of what to set the pressure yourself, since you will not mal-maintain the filter and since you have a welder or some means to fabricate and no issue with digging into your own vehicle in a critical surgery to improve it's PCV as the ultimate DIY'er. What amount of pressure is really ideal for DIY? Again it depends on the aplication and intended usage, so lets look at some more,

if the engine is very 'leaky' say it has 300k miles and the rings are shot. Then you not only might need a strong vacuum to "limp" it around without spilling oil, you also might even need a catch can device or an oil return method for oil that blows out. This is a great example of what catch cans are intended for. They are for engine which have oil systems that are difficult to control, for some reason. For example, Huge ring gaps or poor sealing piston rings, broken pistons, leaking valves, anything that can leak pressure in significant quantity from combustion to the crankcase and there isn't much that can do that, which is why it is tempting to think that an engine is damaged when it has a catch device necessary to operate.
Note that catch cans are additional crankcase volume and therefore reduce the effects of PCV since the orifice is set by te manufacturer and if yoiu have not measured and driled out the orifices for the engine to achieve the desired pressure drop then adding cans/lines will have a negative influence (it will overall increase the pressure in the crankcase since the OEM orifices have not been dealt with (widened))

Another example, I will use a more typical;A stock 5.3L (04-07) engine with a a cam/spring turbo at 500-800rwhp, (I am using Chevrolet examples because this is a chevy forum , I could just easily use 2L or 3L formulas instead) the engine is in good health with say 120k to 150k miles. It hasn't hit it's 185k+ so we are cautious about the factory gaps a bit more than we will be later 200k+ but I digress. As a daily driver it produces very little combustion blow by when run at the right temps and with the right oil, say a 10w40 synthetic at 80*F ambient sea level with oil temp 215*F. Since our intention (this application specifically) is daily driver with high mileage, we prioritize the oil quality over power, and drive the car to high mileage with normal oil change interval lets say 3500 miles per oil change for your 700hp daily driver. The power we 'pay' to run the pcv system can be compensated for with boost so as long as the compressor can flow a little bit extra the pcv system is nearly 'free' power wise to run, until of course if we max the compressor. Extra flow rate means more mass/time and if the air didnt get colder then that means the compressor wheel has sped up to a hgiher rpm, which means exhaust gas pressure has gone up slightly. So even when we increase boost to get the power back there is still some minor energetic costs. I say minor because exhaust pressure has very little to do with overall exhaust flow of the engine (very high power is still possilble with very high exhaust pressures) furthermore high exhaust pressure provides a protective cushion to piistons during the exhaust stroke so it is not unwanted. It's more of an issue when the flow rate volume/time goes too high for the turbine size and pressure escalates either before or after a turbine because of either pipe or the turbine itself being too small. The Pcv flow from the crankcase of healthy engines is negligible in the hurricane of 700hp, or even 350hp worth of flow, as intact modern(01+ for chervrolet) engines don't leak much from their rings it may only amount to a few hp to run the pcv system overall (negligible, almost). Therefore we will ideal to select a range near the max, say 1.55" to 2.25" Hg of vacuum and unlike factory filters our will maintain this range for the majority of it's service life, because we used a high quality aftermarket paper unit. We would use a high quality paper filter much larger than factory to supply much higher flow rate than factory, as well as a larger fresh air PCV orifice to encourage higher flow rates thought the crankcase. The idle/cruise orifice needs to be kept as small as possible to minimize the chances of damaging an oil seal in the event of a fresh air clog, so often OEM will suffice. I recommend the supra PCV valve because it has a very small orifice and seals up reliably for typical boost, let it set the idle cruise diameter orifice for that side of the pcv system. What we are far more concerned with is the Fresh air side, the air filter side, the place where the WOT pcv action comes from. When the engine goes WOT the lowest pressure in the entire system is should be right behind the air filter. That is where we take the WOT pcv to the crankcase from because that is the best source of vacuum in the entire system at WOT. I hope this has been instructional and that you can now see that the point isn't necessarily to hit some exact number of pressure, but more to ensure the flow rate is sufficient to evacuate the crankcase of blow-by gasses and that there is at least SOME Measure of a pressure drop being presented at WOT to facilitate that WOT pcv flow rate and clear the crankcase thus protecting engine oil, and pull on the seals a little keeping the engine cleaner and oil from getting free.

 

Ok help me understand. Right now I'm convinced that my PVC system is not setup correctly. I've removed the supercharger off of the car in order to get better control of the crank ventilation. The smoking has went down dramatically. but i'm still having a hard time trying to break the engine in because i think I have too much crank case pressure or too much ring gap I want to narrow down the problem. My current setup is as follows:

- The driver side valve cover is plumed to my intake air filter with a one way check valve
- My passenger side has a breather on the oil cap and the side breather stem is capped
- the tube that comes out of the top of the engine and connects to the throttle body has a one way check valve and the elite engineering catch can plumed there also

What am I doing wrong. I would love to not run a catch since it not catching anything at this point which leads me to believe my PVC system is plumbed wrong or it's not value added.

 

the engine is brand new and i'm having a hard time trying find a diagram of a stock ZO6 that lays out the pvc system. I also have a secondary issue which is my injectors. The car is supper rich at idle which i think is preventing the rings from sealing properly.

 

On a stock Z, both valve covers go to the dry sump tank port towards the fire wall. 2nd dry sump line goes to intake. Valley plate has a u shaped hose going to intake manifold.