Pcv system
09-16-2017, 11:26 AM
#21
The way people gobble up catch cans you'd think every LS engine gushed oil is all I was really getting at (kind of as a joke)
09-21-2017, 11:14 PM
#22
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Hey guys I'm finding out ive had my PCV routing wrong on my 6.0'stroker. I just swapped from stock intake to NNBS which is brought to my attention that the old set up wasn't quite rite. I'm 98% positive it was pushing oil out of my seals I'll know soon as I'm monitoring it, anyways my current valve covers are off '05 LQ4. Didn't know about an actual PCV valve and I'm seeing some are in the valve cover some are inline. At this point I'm running my passenger side valve cover into the port on the intake the only port in as the other should be in the intake boot before TB. Then for the drivers side valve cover vent I simply have a filtered vent. Until yesterday I had no clue about an actual "valve" I did however experiment with my routing as stated above in reverse order. Which would be drivers side valve cover vent to intake manafold and passenger side valve cover vent with a filtered vent. Here is what happened. When the drivers side was hooked directly to intake manafold it sucked oil like crazy but allowed me to remove oil fill cap with minimal effort.. I now understand why, but not until yesterday in which ive not had time to correct. Anyways because of the oil consumption issue I swapped routing to current set up (passenger side to manafold, drivers side to filtered vent. I believe that the oil consumption is null to very little but now the oil cap is much more difficult to remove with engine running due to the vacuum. I also noticed about a 5psi drop in oil preassure while warm idle which leaves me at about 30psi. With all this being said, I understand the easy safe route would be to route it in stock manor. My question is is it necessary if I'm not sucking oil? It seams like some vacuum would be what I want. Or is it too much? Last and not least is the air flow directional? I couldn't imagine it would be other than perhaps somewhat due to the design in the ports in the valve covers. Other than that flow is flow correct? Any help is appreciated. Some of these things I understand are simple and like I said, I know I can resort to stock routing (didn't know until last night however) but I do really try to get a complete understanding of the things I don't fully comprehend. For obvious reasons! This is one of those things. Ultimately the confusion comes down to the amount of vacuum and the potential different levels of vaccume at different engine speeds and it's correlation to engine protection and effectiveness and the loss or addition of power. I get why the vacuum is needed. I guess I don't understand what's to much and what's not enough. Whew! Sorry for the long boaring rookie questions but this is how I learn. The hard way. PS just replaced a broken COMP beehive spring and bent TSP hardened pushrod in #7 intake. 5000 or so miles mostly daily driving miles, no track time, auto trans, never missed a shift, shift at 6000RPM, and don't get there to often.. mostly just wasting rubber in parking lots but never seeing more than 6 grand. Perhaps this was another issue related to my previously improper PCV venting which was both valve covers tee'd and in at the TB port on the LQ4 intake. Nothing else, nothing from valve covers past TB.. So absolute lack of vacuum. Can't see what else could have caused this. I'm not running overly lean or rich.. idk thanks!
09-28-2017, 12:34 PM
#23
you must have a pcv valve or orifice in between valve cover and intake manifold vacuum
you should not build measurable crank vac with the stock pcv system. if you do then something is wrong.
if your oil cap is hard to remove from suction, and your oil pressure readout is noticeably low then you have too much crank vacuum, and your pcv valve , or orifice is bad or does not exist
the path goes like this for stock, n/a and roots blower pcv
frsh air and vent side
fresh air from main air filter -> main air inlet tube, post MAF sensor barb exit -> passenger valve cover front
pcv vacuum return side
pcv orifice built into valve cover or valley plate, or ls1 style pcv hose assembly (with valve) -> intake manifold vacuum
if you have any noticeable issues like this you should consider a catch can or replace failing stock parts, or both, until around 600hp or turbo/centri-sc boost where IMO you are exceeding the design of the stock pcv system, and need to make some fundamental changes to preserve operation and increase hp handling.
you should not build measurable crank vac with the stock pcv system. if you do then something is wrong.
if your oil cap is hard to remove from suction, and your oil pressure readout is noticeably low then you have too much crank vacuum, and your pcv valve , or orifice is bad or does not exist
the path goes like this for stock, n/a and roots blower pcv
frsh air and vent side
fresh air from main air filter -> main air inlet tube, post MAF sensor barb exit -> passenger valve cover front
pcv vacuum return side
pcv orifice built into valve cover or valley plate, or ls1 style pcv hose assembly (with valve) -> intake manifold vacuum
if you have any noticeable issues like this you should consider a catch can or replace failing stock parts, or both, until around 600hp or turbo/centri-sc boost where IMO you are exceeding the design of the stock pcv system, and need to make some fundamental changes to preserve operation and increase hp handling.
10-07-2017, 11:23 AM
#24
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Ok, understandable. I have it in essentially reverse order pulling dirty air from passenger side & venting (pulling fresh air) from drivers side however I do have an inline PCV valve for dirty air intake post TB side with filtered breather on drivers side fresh air intake.. Was trying to avoid taping into the intake tube and this routing seamed to be the least amount of oil being sucked in As I tried both routes with silly filter on an open line when I ran it the "right" way. I can't imagine the intake pre TB could limit the fresh air being sucked which is what I kept current set up. If my memorie serves me correct the valve cover baffles are the same under each valve cover to. Perhaps this specific build is simply pulling too much air from the stock PCV set up. Catch can is what I've figured I need to do. The thing is I've went from pushing oil in a few spots before intake/TB swap with essentially no PCV venting (didn't understand it until swapped) and no oil consumption, to not pushing oil and consuming it via intake due to proper PCV routing.. sounds like a need a catch can and a way to reduce the air flow so I'm still getting enough vacuum to keep from pushing oil. Thanks for getting back!
