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The dreaded PCV system question!! I had a LS1 burnt tons of oil. Bad experience with the motor. So then I got a 6.0 and had it rebuilt. Now I want to get the PCV system right this time. So I have the following
LS6 Intake
LS6 pcv valley cover
dual vented passenger valve cover
single vent driver valve cover
it is NA atm and I have the mishimoto catch can. Now I’m considering getting one of the motion race work breather catch cans, and deleting the PCV and capping all the ports/vents, or is that not advised? It is not a track car. Just fun weekend warrior. Should I reuse the mishimoto catch can? Or get the breather cab and delete the PCV? Or what other combinations do you guys recommend?? I’m all ears and open to suggestions please thanks!
I made one of the diagrams to better help understand what I meant. The red is just the capped ports/vents. And I would be welding AN bungs to the covers.
what is you reason for wanting to delete the pcv system (you do not have to). if the mishi-can is a closed unit just put it between the valley and intake manifold. cap or loop driver and passenger cover rears, and run passenger cover front to top of the throttle body, and it will be to spec. if/when you have oil getting in front of the throttle body, circle back to this topic.
what is you reason for wanting to delete the pcv system (you do not have to). if the mishi-can is a closed unit just put it between the valley and intake manifold. cap or loop driver and passenger cover rears, and run passenger cover front to top of the throttle body, and it will be to spec. if/when you have oil getting in front of the throttle body, circle back to this topic.
Thought I'd add what I did. I read a ton posts here and in a few other spots and didn't really see what I had so I thought I'd post it up. To be honest I think I only got to page 6 or 7 of this thread but I got a ton out of the early posts so I put what I learned to what I had.
I have a Gen 3 4.8 SBE with a turbo out of Express 2500 van. Single Catch can (Mike Norris) config. Plan on daily driving with a max of 8 pounds on the street, will turn it up to 14 at the track 2-3 times a year.
If this doesn't do it I'll probably get a second can for the clean side. I might build a cold air intake that allows me to plumb the clean air before the turbo, depends on the blow thru I get but for now it routes to atmosphere as the filter is attached directly to the turbo. Here is the pic of the filter/turbo, this was pre-catch can install.
Does it mess with the tune at all if I run a breather cap instead of a line from the passenger front VC to TB? I understand it would be an open loop system venting to atmosphere.
Are you doing away with the PCV system entirely? If so then you could run a little leaner as the tune right now has factored in the blow-by gases entering into the intake manifold. Is it enough to matter? Probably not and I don't think it would hurt to try. You can always throw a new set of plugs in it after the change and see what they look like after a hit.
Are you doing away with the PCV system entirely? If so then you could run a little leaner as the tune right now has factored in the blow-by gases entering into the intake manifold. Is it enough to matter? Probably not and I don't think it would hurt to try. You can always throw a new set of plugs in it after the change and see what they look like after a hit.
Why would the blow-by affect the mixture? Seems to me that the blow-by is either going to be pre-combustion (a mixture with the same AFR the ECU is targeting), or it's going to be post-combustion (exhaust - where the oxygen and fuel are no longer available) so either way it shouldn't change the resulting AFR.
Are you doing away with the PCV system entirely? If so then you could run a little leaner as the tune right now has factored in the blow-by gases entering into the intake manifold. Is it enough to matter? Probably not and I don't think it would hurt to try. You can always throw a new set of plugs in it after the change and see what they look like after a hit.
No. I'm installing a catch can on the dirty side, between the LS6 valley cover and the intake. I don't have a port on my TB and thought I'd rather vent the clean side rather than add a second CC and install another port in the TB or bellows.
Yes. This would no longer measure PCV air supply through the maf.
Originally Posted by blsnelling
Does it mess with the tune at all if I run a breather cap instead of a line from the passenger front VC to TB? I understand it would be an open loop system venting to atmosphere.
Why would the blow-by affect the mixture? Seems to me that the blow-by is either going to be pre-combustion (a mixture with the same AFR the ECU is targeting), or it's going to be post-combustion (exhaust - where the oxygen and fuel are no longer available) so either way it shouldn't change the resulting AFR.
Anytime you have the intake manifold pulling vacuum on the engine and throttle body you are introducing blow-by "gases and moisture" into the intake manifold-post MAF and yes that doeas affect the fuel mixture and the tune and if you remove that from the equation what do you think will happen?
OP if your set on running PCV why not install a a check valve on the line going to the throttle body or run dual cans. Personally I don't see any problem with capping off the throttle body and installing a T fitting on the line from the valley cover to the catch can and connecting the passenger line to there. All your doing is rerouting that line through the can first before entering the intake manifold. Does it really matter how it gets in there to begin with?
OP if your set on running PCV why not install a a check valve on the line going to the throttle body or run dual cans. Personally I don't see any problem with capping off the throttle body and installing a T fitting on the line from the valley cover to the catch can and connecting the passenger line to there. All your doing is rerouting that line through the can first before entering the intake manifold. Does it really matter how it gets in there to begin with?
You can't combine the dirty and clean side like that. That's why you use a second can.
I did consider a one way valve on the clean side line to the throttle body. But, if you overcome the PCVs flow capability at WOT, you'll pressurized the crankcase. That's why many use a breather. The right way is another catch can.
Just remember the same blow-by gases that are coming out of your valley cover and being sucked through your catch can is the same thing coming from that passenger valve cover.
Man I never get any oil in my catch can and I'm still on the ls1 valley cover. As long as I don't have to replace my rear main seal due to crankcase pressure being too high, I'm good.
I would say run it to the bellow post MAF that way your not pulling vacuum on that line too and is only being drafted in while at idle and WOT. I have seen images on this forum of people running a breather off the passenger valve cover.
Man I never get any oil in my catch can and I'm still on the ls1 valley cover. As long as I don't have to replace my rear main seal due to crankcase pressure being too high, I'm good.
Installing a catch can of any sort in the stock vent line will catch some oil during blow by exit but will also increase crankcase pressure due to the inherent restrictions.
-for higher than stock power levels you would want this vent to be larger than stock while also introducing filtration capability
-Even then you must recirculate all this blow by which is mainly hot oxygen depleted air versus cool oxygen rich air that would make the most horsepower, in order for the system to work correctly during normal PCV vacuum cycle.
-after this you would still need another catch can on the return side of the system to reduce your usual PCV oil consumption.
All considered and handled in a single unit within our 'wild' systems using my PCV can which is why I invented it. 🙂
It's just a mightymouse mild 4th gen setup using AN fittings on bungs that I welded on the valve covers. I tried making my own but the built in PCV valve that mightymouse has in his cans is they way I decided to go. The layout I used can be seen here, less the dotted line:
-not have the fumes released to the atmosphere -keep smell down -keep oil out of the intake -release crankcase pressure so that I don't blow my rear main seal -ensure blowby fumes are not consumed so that power is made with fresh air -no vacuum leak -don't allow unmetered air into the system at WOT
I should have just bought his setup in the first place instead of playing around with dual cans and all that other stuff. I bought his mild can and it was a great mod.
Last edited by 5.7stroker; 01-30-2020 at 08:39 PM.
10-20-2019, 01:56 PM
