Ok, it is pretty much established that a stock pcv setup will not be very happy under boost. Ive heard many options to replace this:

1.) Put a heavy duty check valve (brake booster check valve) in the pcv line and connect to intake vacuum. This should function decently under vacuum, but nothing would happen under boost. With sustained continuous boost, this would be no better than no PCV at all.

2.) Run the pcv as usual, but connect to the intake in front of the turbo (or blower). This should see vacuum at all times, but droplets of oil from the valve covers would not play well with impeller wheels.

3.) Same as #2, but use a catch can in the line between the pcv and the turbo inlet to retain any oil vapors. This strikes me as the best compromise, but also probably the most expensive.

4.)Not run pcv at all, run breathers. Everything I have read says this is a bad idea. Water/fuel/exhaust vapors from blowby will contaminate the oil, reducing oil life etc.

Would it be at all feasible to use the AIR pump from the original emissions equipment, but with a line connected from the suction side of the pump to the pcv valve? I havent looked at my pump since it "fell" off several years ago so I dont even know if it can be connected like this, I would have to dig it out and see. But it strikes me that positive ventiliation could be achieved at all times regardless of boost, and there would be almost no cost involved.

Does anyone think this would work / has anyone done this?

 

FWIW, I'm running option 4, and getting too much blowby, so that isn't satisfactory. I think a vacuum on the crankcase is a good idea for keeping seals happy, minimizing leaks (my valvecovers leak like a seive, even w/ RTV), and keeping the spooge controlled.

Add option 5 - an exhaust evac kit, where you weld angled bungs to the collectors, which draws a vacuum on your crankcase at all times, and more with higher exhaust flow (WOT). It comes with a simple air/oil baffle to keep as much oil out of the exhaust as possible. Adding a separate air/oil separator is probably the cleanest solution w/ the evac kit, but it's more weight and clutter in the engine bay.

 

Exhaust evac kit? I understand the principle behind it, and I could believe that it would work nicely on a low backpressure system, but i cant imagine a collector at 10-15 psi could pull a vacuum on a crankcase at near atmospheric pressure. Link?

 

I tried option 2 and it didn't work for me, I had no vacuum at all and the only time I did see vacuum was at +3500 rpm's and even then I only saw the needle move a tinny bit.

 

I can't imagine your backpressure is that high. Maybe 2-3 psi at the most <shrug>, even with a Flowmaster muffler. Anyone have empirical numbers? Moroso & others make a kit. It should be listed from www.moroso.com, or in Summit/Jegs.

Tony - Thanks for sharing #2 didn't work for you. Strike that off my list...

Andris

 

What about using a PCV valve designed for boost, say for a GN? I have one on my 89 trubo cavalier (Carquest PN- EC V242). When you blow through it, only a very small amount of air leaks past, compared to a new OEM style pcv valve for the NA appliction. Buy one of each, and try it- you'll see what I mean. I run a regular open element breather on the one valve cover, and the PCV valve is in the other. My cavvy now has 176k miles on it, an shows no oil mess near the breather due to blow-by with this set-up.

BTW, I think th GN guys have an aftermarket PCV valve that is designed to completely seal off under boost. I don't know where this can be obtained though.

 

Bringing this back from the dead, any good answers out there (especially for a turbocharged application)?

I’ve been seriously looking at somehow to do this with a turbo, but the fact is that these setups are designed to plumb into the collectors on a set of headers, where you have a venturi affect. It’s not so much backpressure that will keep it from working, but no real venturi in the exhaust system on a turbo car.

The thought that I was having was necking down a section and creating one, but I wonder how effective this could be made without hurting the backpressure that the turbine sees effecting pressure at the exhaust valve, I/E pressure ratio…

Well, this is what all the OEMs do. Some actually put fittings on the inlet elbows of the turbo, like the 2.3L fords, and others in assorted places in the ducting. It works, but it’s messy, that’s the reason why there are instructions floating around on just about every OEM turbocharged car’s site on cleaning oil out the intercoolers…

 

mark what are you planning/running for your pcv system?

 

As long as you have an open exhaust after the evac bung, why shouldn't it work? Other than the turbo smoothing out the exhaust pulses, why would the downpipe not act the same as a collector in a header? You could create a venturi, but I'd run calcs first to see how much pressure is increased in front if it, and how large (diameter change) it would have to be to get a worthwhile effect. I had one track day w/ the EVAC kit installed, and had oil leaks everywhere, so it didn't work with my restrictive exhaust (both turbos feeding into a 3" SLP catback). The new exhaust is unmuffled 3" duals out the side, so that should fix that.

 

Here is what we do with SyTy: Breather on driver's side valve cover. Both stock PCV valves on passenger side. One routed to TB one routed to Air Intake duct in front of the turbo. (this is a quote from one of the threads there)...I cant phrase it any better that this... There is a tube that goes into the valve cover hole on the pass. side that the 2 PCV valves are mounted/hooked up to...this part is dicontinued from GM, but can be made pretty easily in a home shop...this is what I will try first, see if it will work on a V8...which I don't why it wouldnt...SyTy run pretty high boost often...up to 25 psi...

 

Hoollly cow I had no idea this was an issue( PCV system) . Next season my singlke turbo goes on .

I liked the sound of running the stock PCV and then have an accumulater ( sp lol ) inline to catch any vapor or oil . Is this a good choice then ? I am trying for a completely smogg legal setup here in S. Ontario . So I can;t run any breather type setups . The Smogg ****'s are many up here in the spring/summer.

TIA

 

sorry to bring this post back from the dead (but give me credit I was searching). I'm wondering about what to do wih the turbo setup also. I have how do we get decent vacuum to the PCV. my setup as is only has a little box/baffle setup on top of the valve cover with a hookup into the airfilter. once I put a turbo on this car what do I do with the PCV. I don't really think the exhuast system is going to be a good setup for me at this point. but if I'm not goign to get vacuum at the turbo what could I do? blowby is bad

 

I see you are running a 1.3 liter (80ci)......same as a Harley EVO. I was talking to someone the other day about putting a turbo on one. What size turbo you running on that 1.3 liter? I have one in mind, but I would like to hear about a real world setup.

As for the pump, check out Moroso...they sell them.

 

common turbo upgrade for it is a t04e. I have seen them using t-76 or t-88 turbos though.
I can get some info on the stock turbo that they use with the a/R and stuff.

the car I'm using though is a little different but rather the 76 honda with the 1.6L motor. the rx7 doesn't have a turbo on it.

 

Yikes, must use a huge N2O bottle on that thing for the street. I would guess that it would run more off the N2O than the turbo boost on the street. Talk about compressor surge.

No need to do that. I was just curious what was on it.

 

no N2O are used on them. full boost usually by around 3200-4000rpms depending on the size of the turbo.

there was a guy running a to4r using 25psi of boost on the street. made something like 500-550hp off one. was running into the 10's I think over in japan. think full boost on his car was still in the 3000rpm range.

 

Wankels are almost somewhat sort-of equivalent to two stroke piston engines, in that you can nearly double the displacement to compare with a 4-stroke. 2.6 or thereabouts, hence the larger turbos. Remember, they have an easier time revving to the moon as well.

 

not only that but the exhuast is a little different as well. unlike a piston motor where on the exhuast tract you have a large valve, then a nice bend and usually a few other restrictions on the exhuast, the rotarys exhasut port is just a straight hole. no valves, no bends no nothing. it goes straight out the exhuast. and most setups with the turbo mount the turbo within just inchest of the exhuast port so the turbo can be mounted as close as possible.


but come on guys back to the question at hand

 

I would use a PCV valve to the intake on one valve cover (like stock). An additional check valve can be used if needed as described in option 1.

On the other valve cover I would use a breather with a hose to between the air filter and turbo.

With this setup you have a normal working PCV systen when not in boost. Fresch filtered air will enter the breather and then go thru the PCV to the intake. When in boost the PCV / check valve will close and the crank case gasses will go into the turbo still maintaining a small vacuum in the crank case.

This will also minimize the amount of oil going to the turbo as the air normally flow from the turbo to the valve cover. That should keep the hose almost oil free.

If a catch can is used then that can probably be 'self cleaning' if designed right. The oil could be sucked back into the valve cover when not in boost.

 

Stock DSM's are set up that way, and over time the turbo/piping/IC get really covered in oil because of how much actually does go into the pre-turbo intake pipe.

 

trick from the DSM world...

Try using lines from PVC ports (3/8" hose each) and then join them (to a 1/2" line) and route it to a beather tank (with a drain plug)... you could also take a line from the top of that tank run it through a small filter and run it to the low pressure side creating vacuum to pull air out of the case/valve covers.

why the second filter? to keep the oil from getting into intake tract. But also make sure you have come type of site to check oil level in the tank... One of those clear plastic universal things with big connectors work great.
----------
they are also not set up right from the factory...

 

Did you ever get a good test on this? I’ve considered something like that but the basic arguments against it working with a turbo is that you want as little restriction behind the turbo as possible and you don’t get enough of a vacuum in the evac setup without some sort of venuri (collectors on an NA setup) which would show up as backpressure behind the turbos.

I’m not sure that I 100% believe that it’s not possible to get it to somewhat work without a measurable performance loss, but again, I’m not positive.

Andris, with your setup and your road race inclinations you’re not worried about slowly oiling down your tires? I could see clearing them off in the burnout box at the dragstrip (of course, you could have catastrophic problems if you broke something mid track), but you don’t stop and clear off your tires every 10 or so seconds on the road course.

Most people consider the sy/ty setup to be the optimal turbo setup, just because most other OEM turbo setups have a PCV that only works well under some conditions, where the sy/ty one attempts to have one side functional under high vacuum conditions and the other side under boost conditions…

I don’t agree, since every sy/ty setup that I’ve ever seen has had the PCV system fouled beyond belief and they almost always have to be totally disassembled and cleaned out at tune ups.

Most normal setups just connect the PCV valve line to the inlet of the turbo, let the inlet ducting get fouled up and only works some of the time.

Honestly I haven’t seen an OEM setup that works well and doesn’t make a mess.

Huh, take a look at some of those parts… looks a lot like you can build it yourself for cheaper, as a matter of fact I have built one that I intend to experiment with soon.

I don’t think that I’m following, do you mean that you have a hose fitting as part of the valve cover breather assembly and a hose going from there to the ducting in front of the turbo?

I’m assuming that you mean a small vacuum from the ducting in front of the turbo, if I understood you correctly above then what would prevent that from just sucking air in from the breather rather then the crankcase?

What is keeping the oil out of the PCV system that way, I don’t understand what is different then normal?

Naw, not a good idea. If the PCV system is designed right it should be sucking up the blowby gasses, water vapor and other crap that fouls the oil and ends up making acids in it. You really don’t want to dump that sludge back into the engine.

huh, are you talking about like one of those clear plastic fuel filters?

Otherwise it just sounds like every other OEM turbo PCV setup.

I know on my brother’s car he finally gave up, the only solution that he came up with that kept him from making a mess was to ditch the PCV setup entirely and just make a housing/can that fits around the breather which is mounted high on a stand off to catch the crud that would normally come out and cover your valve covers (and even with quite a bit of blowby now it keeps things surprisingly clean).

MOST heavily boosted cars end up doing something like that and just deal with the mess, as a matter of fact the only setups that I’ve seen that are making more then 500hp and still have PCV systems at all are some of the modified lightnings and cobras, and what they seem to do is stick with the stock PCV (which from what I can tell is very similar to every other OEM setup), but just put a filter (like the clear housing ones that you use on an air compressor line) in the PCV line to strain out a lot of the oil/sludge.

Since I’m a firm believer that some sort of evac is necessary and highly beneficial for the long term life of the engine I’m trying to come up with something better, not sure what the final deal will look like yet…

 

Actually, I did get a great test of this at the NFME event at Indy a few weeks ago. At idle, I pulled off the vaccuum line from the breather, and it had a pretty decent pull. I gave it some throttle, and the vac just got stronger as rpms climbed. This is with the side exit exhaust & no mufflers, so there isn't a restriction. The bung is welded onto the 2.5" downpipe (won't have a chance this season to fab a larger one) on the passenger side turbo, at about a 45 degree angle, about 20" from the turbo. No oil anywhere in the engine, and nobody noticed anything coming from the tailpipe at WOT. We pulled the car off the trailer in Ohio and drove it the rest of the way (with diesel truck dino oil in it), so it's possible that helped the rings seal, as there was minimal blowby now.

 

on my honda the stock crank vent is only setup to go into the bottom of the air filter housing. so it doesn't even really see any vacuum I would guess. so I'm sure putting the hose into the turbo intlet would be ok as long as it didn't scrwe the turbo up with all that oil possibly being drawn into the turbo. but I don't see it beign as efficient as it should. about the only way I'm seeing a decfent method would involve using an external pump (smog pump might work) which should be able to pull a decent amount of vacuum and then run that into the turbo inlet or open vent in with a little catch can either way.
but then comes extra pullies or electrical wiring depending on how the airpump is driven.

the only other thing I can think of is on the intake tract itself in the piping before the turbo putt a little venturi like object in there with a hose going to the outside connecting to your pvc. just like a carb with the fuel. might work but I don't know how well at low loads.

 

Well that’s a pretty positive test…

By “bung” do you literally mean a bung or just a tube like the moroso setup or what? Any pictures of what you did?

 

No pics handy. It's the tube from a Moroso kit. Simple 45 degree miter cut on the end of it, about 2" long, and then threaded for the check valve.

 

That’s alright, just knowing that it’s the moroso setup is enough for me to imagine what you did pretty well… did you use a breather in both VC’s or just one?

This gives me more ideas, I may just ditch my pump idea and give that a shot… probably stick a catch can in the line and could still sneak past emissions…

 

Wondering about the evac into the down pipe thing ....

Just run a line from the PCV on the valve cover , to a bung on the down pipe ? Was that it ? Or do you add a catch can inbetween ? Also I am wondering how this would affect emmissions reading and/or converter life .

 

i know it's a bad word but the ford electric smog pumps will work. that is what the aeromotive kits are. they are on ford sedans.

 

I'm wondering if this will work on a more restrictive exhaust (single 3" to rear of car) by mounting it toward the end where there won't be much backpressure. It would make for a long evac line, but is there any reason this wouldn't work as well? With a single in/out muffler one could put it behind the muffler since the mass of the exiting air is the same, but on a setup without a muffler at all (or with a straight through resonator like mine) it might work just as well putting it a little further upstream, perhaps right before the bend going over the axle. Just some thoughts.

Other than that, I still wonder how well the original poster's idea would work, just using the ol' smog pump. Heck, a little oil running through the thing might help keep it lubed so it lasts longer, heh.

 

I use the Ford electric one, as do about 6 other local cars. No problems- very happy with it

Matt

 

oil will disslove the grease in the bearings and is not thick enough to keep them alive.

I know that the GM electric pumps won't survive, I'm not sure about the ford ones... one thing to remember with that approach is even if some race cars get away with it, they put on a lot fewer miles then even the most "weekend only" street/strip cars, I'd be suprised if it lived long if you put some miles on the car.

 

Sorry guys didn't want to re-open this thread but I need help. I've read and searched several threads but haven't come to the conclusion on how to properly route my vacuum lines with the installation of a Paxton SC and no smog devices. Several years ago I had it all plumbed correctly but yanked everything out and forgot how to re-route the vacuum lines. Can some provide pictures or a detailed diagram of how the vacuum lines should be routed.

Added pictures of current setup but vacuum lines not correctly setup for example picture with a T connector and the input of the blower were its tapped with a fitting I believe should be routed somewhere etc....

 

Sorry for the late reply.

A breather hose from one valve cover to between the air filter and the turbo, almost like stock. On a stock car this hose goes to the throttle body before the throttle.

A 'stock' PCV valve from the other valve cover to the intake just like stock.

During engine vaccum this would work exacly like stock pulling air from the engine air filter, thru the cank case and then thu the PCV valve into the engine.

During boost the PCV valve closes. At the same time a small vacuum is created before the turbo and the crank case gasses are eaten by the turbo instead.

 

Thanks for the quick response. Although what you've explained makes sense could you possibly lay it out in a diagram (could be hand drawn) or a picture. Also what are the specific parts need (i.e. pcv, check valve, hoses etc.) I'm hoping to get my car in good running condition by this weekend but can't afford to continually have blowby such as oil seeping out of the valve cover areas.

Thanks in advance!
Joey

 

All stock parts. You might want a PCV from a turbo application as the stock one might not be designed to close during boost.

 

Has anyone every used a crankcase evacuation system to eliminate this problem? If so please provide feedback.

 

so far I am likeing the ...

running your PCV ( stock location ) to a catch can ...and a line to the turbo inlet tube

Or am I missing something ?

 

I guess my problem is I don't know how everything was originally setup. Do you have a detailed diagram?

 

I swear I replied to this earlier....

The GM A.I.R. pump at least any that I have seen on a GM application can not easily be used as a crank case evap or vacuum system, since the fresh air inlet is behind the pulley.

However Ford has an A.I.R. pump that has inlet and outlet with removable fittings, I have one that I am planning to use as an EVAC system. I don't know what application it's from though.

 

No, you replied to Dave's and this is by slickrock55. There are two of these threads floating around at the moment, lol....


What's the opposite of deja-vu?

Vuja-de.

 

Would it be an option to use the electric smog pump under boost only (like with a hobbs switch for activation) to lengthen the life of the pump? And set it up with some sort of dual setup with check valves to use a normal PCV system when not in boost?

 

Be aware that there have been literally tons of recalls on the electric smog pumps when used as designed, they just don’ t live. GM went so far as to redesign the LT1 ones 2x, and then gave up and ditched them on some cars as a service bulletin (on the B-bodies, which from what I understand, disabling an emissions device as part of a recall takes something akin to an act of god to get past the feds, like proving that all the possible alternatives can’t work and would blow up and kill everyone…).