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Old 04-17-2012, 10:30 AM   #1
turbojose
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Ok... so am I wrong, or are most guys that are running a lot of boost also running an open to atmosphere type PCV system? I have been trying to run a closed system on a 16v +t conversion, and it seems that everything I try just doesn't work... Is there anybody using a closed system that is proven to be effective? Last thing I tried, was a open 5/8 hose(no flame trap/restrictor) from the oil separator box to a ebay catch can, then to the pre turbo inlet pipe.... only thing I got was about a 1/2 quart of oil in the intercooler and intake track!!!! and the ebay catch can had nothing in it!!!!! what gives. would have been better to just leave it alone. any help please?
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Old 04-17-2012, 10:47 AM   #2
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Did the 'catch can' have baffles inside? A lot of them are just boxes with two inlet/outlet ports and one drain, and they do nothing in terms of seperating the oil from the vapor. I'm working on a design that's based off intake designs on drag racing boats, as they use acceleration of air in a high pressure zone, then a 180deg bend to help shed moisture onto foam(I'll use sst wool). If it works for water, it will work for oil, so I'm going in that direction and will post pics when finished. So: Run one with baffles, not just the open can style.

Problem I hear about venting to atmosphere is you're losing crankcase vaccum which apparently helps with sealing a motor. Of course this is just off what I've read. I've never vented to atmosphere.
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Old 04-17-2012, 02:00 PM   #3
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At wide open throttle there's no "vacuum" to be applied to the crankcase anyhow with a traditional PCV set up. You only get vacuum at closed/light part throttle conditions. Even less so with a boosted application. The benefit of pulling a bit of vacuum in the crancase is simply that it reduces the work the pistons do pushing air out of the way on the BACKSIDE of the piston. More vacuum in the crankcase equals less air to push around which frees up a bit of HP. But only if you can create some vacuum under heavy throttle open scenarios. For that you generally need a vacuum pump set up.

To the OP - you need the oil traps/seporators to knock the oil out of the crancase vapor. Even if you vent to atmosphere (solves oil in intercooler) you're going to make an oily mess wherever you vent unless you knock out the oil. Removing the factory baffles hurt you in this case.
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Old 04-17-2012, 02:06 PM   #4
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^ The PCV pre turbo inlet provides plenty of vaccum. Should be pretty close in relation to the boost you're seeing on your gauge, according to some engineers here. Pre turbo = vaccum proportional to boost.
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Old 04-17-2012, 05:12 PM   #5
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Anybody drill out the intake nipple a little for a little more pull on an older engine?
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Old 04-17-2012, 05:30 PM   #6
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Quote:
Originally Posted by atrokz View Post
^ The PCV pre turbo inlet provides plenty of vaccum. Should be pretty close in relation to the boost you're seeing on your gauge, according to some engineers here. Pre turbo = vaccum proportional to boost.
I've wondered about that. Do you have something that illustrates this? Have you tested it?

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Anybody drill out the intake nipple a little for a little more pull on an older engine?
Which one? Just one of the ports?

Anyone ever check out the nipple off the stock oil separator? It's tiny internally.
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Old 04-17-2012, 05:35 PM   #7
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Quote:
Originally Posted by atrokz View Post
Did the 'catch can' have baffles inside? A lot of them are just boxes with two inlet/outlet ports and one drain, and they do nothing in terms of seperating the oil from the vapor. I'm working on a design that's based off intake designs on drag racing boats, as they use acceleration of air in a high pressure zone, then a 180deg bend to help shed moisture onto foam(I'll use sst wool). If it works for water, it will work for oil, so I'm going in that direction and will post pics when finished. So: Run one with baffles, not just the open can style.
^^This. I just got one from ebay and will be modifying it. The ports are just as you said, just ports. No routing into the can itself and no baffling.

I'll be opening up the ports for 1/2" NPT fittings and one of them will be attached to a copper tube with perhaps a double 180° bend with soldered plates for baffling.

I'll post pics in the "more crankcase ventilation thread"
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Old 04-17-2012, 05:39 PM   #8
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Quote:
Originally Posted by turbojose View Post
Ok... so am I wrong, or are most guys that are running a lot of boost also running an open to atmosphere type PCV system? I have been trying to run a closed system on a 16v +t conversion, and it seems that everything I try just doesn't work... Is there anybody using a closed system that is proven to be effective? Last thing I tried, was a open 5/8 hose(no flame trap/restrictor) from the oil separator box to a ebay catch can, then to the pre turbo inlet pipe.... only thing I got was about a 1/2 quart of oil in the intercooler and intake track!!!! and the ebay catch can had nothing in it!!!!! what gives. would have been better to just leave it alone. any help please?

Did you get one of these?

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Old 04-17-2012, 05:54 PM   #9
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Originally Posted by Ursan View Post
I've wondered about that. Do you have something that illustrates this? Have you tested it?
.
We didn't graph it out or use gauges, but basic logic defines that there will be an increasing vacuum as the vacuum through the airbox increases when the turbo increases it's rpm. It will reach a limit, and the returns will diminish, but there will indeed be more vacuum at boost than at idle. I should find a vac gauge I don't mind getting oil vapors in to show numbers.
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Old 04-17-2012, 06:04 PM   #10
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Quote:
Originally Posted by Ursan View Post
^^This. I just got one from ebay and will be modifying it. The ports are just as you said, just ports. No routing into the can itself and no baffling.

I'll be opening up the ports for 1/2" NPT fittings and one of them will be attached to a copper tube with perhaps a double 180° bend with soldered plates for baffling.

I'll post pics in the "more crankcase ventilation thread"
Do it. I gotta stop by my old shop to get it done. Already have a few plans sketched out. Thinking of doing either a spiraled tube feeding off the inlet, with gradually increasing holes on the outside ID of the helix, or, a baffle formed from sheet metal going: Large area - small area - Large area - smooth long 180 bend up - gradually smaller area. They both should separate moisture well using both condensation and centrifugal force, so it just depends what materials and tools I'll have at my disposal.
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Old 04-17-2012, 07:09 PM   #11
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I believe if you're developing any significant vacuum on the suction side of the turbo the inlet system is far from optimal. Logic doesn't dictate that as boost builds, so will vacuum on the other side of the compressor. Compound turbo set ups illustrate this quite well. The compressor takes the fluid stream at a certain pressure - and compresses it to a higher pressure. Start with a lower absolute pressure (e.g. - vacuum) and you'll get a lower pressure on the other side of the compressor. If you have a restrictive inlet (classic case is a clogged air filter) you'll start to get vacuum at the inlet -- and reduced performance.

I believe the fundamental problem the OP is facing has to do with no oil traps or baffles to knock the oil out of the vapor stream. Crankcase pressure is what's forcing the flow out --- not a significant 'pull' from the inlet side of the turbo. But - it's just an opinion.

fwiw - I've played around with alternative crankcase ventilation scenarios over the decades. Other than venting to atmosphere or having it hooked up to the intake (with a check valve for boosted set ups) everything I've tried has resulted in the same result the OP got. Oil from the engine showing up in places I didn't want it to show up --- outside the crankcase. Usually, in my experimentation, which included connecting it upstream of the intake or power adder, all I succeeded in doing was elevating crankcase pressures thus forcing oil out of the crankcase and past the front and rear crank seals.

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Old 04-17-2012, 07:17 PM   #12
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OP needs to get his crankcase vapors to slow down and turn a few corners so that the oil will drop out.

OP if you've got multiple quarts of oil in the intercooler..... Time for something different!

My Turbo six vents to atmosphere.... via the standard vent. Very little crankcase vapors under boost in mine.
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Old 04-17-2012, 07:38 PM   #13
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"Very little crankcase vapors under boost in mine." Good cylinder seal. With more boost (or dynamic compression) usually comes more blow-by and the resulting higher crankcase pressure.
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Old 04-17-2012, 07:58 PM   #14
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Quote:
Originally Posted by M.H. Yount View Post
I believe if you're developing any significant vacuum on the suction side of the turbo the inlet system is far from optimal. Logic doesn't dictate that as boost builds, so will vacuum on the other side of the compressor. Compound turbo set ups illustrate this quite well. The compressor takes the fluid stream at a certain pressure - and compresses it to a higher pressure. Start with a lower absolute pressure (e.g. - vacuum) and you'll get a lower pressure on the other side of the compressor. If you have a restrictive inlet (classic case is a clogged air filter) you'll start to get vacuum at the inlet -- and reduced performance.

I believe the fundamental problem the OP is facing has to do with no oil traps or baffles to knock the oil out of the vapor stream. Crankcase pressure is what's forcing the flow out --- not a significant 'pull' from the inlet side of the turbo. But - it's just an opinion.
I'll hook up a vac gauge when I can to test it, but I do believe there are more cfms of air as higher rpms are reached. There has to be in order for air to be compressed "more". Same as a turbine engine. As rpm speeds increase, higher volumes of air are injested. I guess we'll know as soon as I test it. Either way, yes, baffles to some degree are needed in the CC. I'll go the condensation via pressure differentials route to achive cleaner vapors.
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Old 04-17-2012, 08:59 PM   #15
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Interesting discussion!

I'm researching the same topic at the moment and have yet to decide which route I'll take with my car.

Regarding the vacuum in the intake (pre-turbo), I can say this much: On my old 850 Turbo with only a K&N filter of unknown age (PO installed it) and otherwise stock at 16 psi, I saw only 1.5-2 inHg in the turbo inlet at full boost/RPM.

I don't think it's so much a measurable vacuum caused by the engine/turbo that "pulls" the vapors from the PCV hose on the stock setup, but the vacuum-created venturi effect of the air rushing past the PCV inlet at a 90 degree angle. Same concept as the PCV venting into the exhaust--which may just be the best way to do it if you don't have to worry about emissions.

Speaking of using centripetal force to separate out oil and water from the crankcase vapors, I had an idea about this..

What about using a fuel cooler as a catch can to help separate out the oil and water? Ya know, the small canisters with several coils of tubing inside, designed to be surrounded by ice water to cool down the fuel post pump..

Just thinking out loud here.
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Old 04-17-2012, 09:56 PM   #16
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I'll post pics in the "more crankcase ventilation thread"
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Old 04-17-2012, 10:07 PM   #17
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Did you get one of these?

No... I actually got the 14.99 one... serves my right!! I have seen many with different prices, I was just hoping someone is using something or doing something that definitely works... I hoping to not pay and pay and pay until I get it right. Isn't someone using something that just works.
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Old 04-17-2012, 10:14 PM   #18
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The way to get vacuum preturbo is a restrictive inlet system. I've posted this before, but with my 4 inch intake , 25lbs of boost pushing 70lbs of air/min, I logged less than 1 inch vacuum. With the gm vacuum pump I saw like 3 inches under full boost.

I think we see a low pressure draft, not vacuum.
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Old 04-17-2012, 10:43 PM   #19
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Quote:
Originally Posted by Nathaninwa View Post
The way to get vacuum preturbo is a restrictive inlet system. I've posted this before, but with my 4 inch intake , 25lbs of boost pushing 70lbs of air/min, I logged less than 1 inch vacuum. With the gm vacuum pump I saw like 3 inches under full boost.

I think we see a low pressure draft, not vacuum.

That's what I thought.

My pre-turbo intake:



Is just a couple of 45° bends. The MAF is just at the radiator support and the filter is tucked up behind and inside the bumper C-channel.

I've never gotten any vacuum there.

I was able to get "some" when I drilled a 1" hole and installed a grommet. Then I took a 3/4" copper pipe with a 45° hash cut into it facing in the direction of the turbo which causes a slight venturi. Not a lot of vacuum, but certainly more than before. (1" at best)
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Old 04-17-2012, 11:39 PM   #20
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Quote:
Originally Posted by Nathaninwa View Post
The way to get vacuum preturbo is a restrictive inlet system. I've posted this before, but with my 4 inch intake , 25lbs of boost pushing 70lbs of air/min, I logged less than 1 inch vacuum. With the gm vacuum pump I saw like 3 inches under full boost.

I think we see a low pressure draft, not vacuum.
That's definitely the better way to word it. Maybe a pump setup is really best.
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Old 04-18-2012, 12:51 AM   #21
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Quote:
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That's definitely the better way to word it. Maybe a pump setup is really best.
Does any real/imagined benefit justify the effort?

A well-sealed engine doesn't make that much for crankcase vapors!
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Old 04-18-2012, 06:17 AM   #22
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Well what if an engine isn't well sealed? Being over 200k and all? What you're saying is just vent to atmosphere? Would make things easier though. Just run it through a catch can and out past the tranny. What are the disadvantages aside from loosing some negative pressure in the crank case?

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Old 04-18-2012, 09:17 AM   #23
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Quote:
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Well what if an engine isn't well sealed? Being over 200k and all? What you're saying is just vent to atmosphere? Would make things easier though. Just run it through a catch can and out past the tranny. What are the disadvantages aside from loosing some negative pressure in the crank case?
one of the major disadvantages I've been told, is that there are plenty of fumes in the engine bay, and that after a long drive if you park in the garage, then the fumes are bad in the garage?? Don't know of any other disadvantages, but for me, that's enough.
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Old 04-18-2012, 10:55 AM   #24
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Every car on the road had a road draft tube before 1968. Somehow we lived and even parked the cars in the garage.

Crankcase vapors don't smell very good. Vent them such that you won't end up smelling them in the car and so that they won't swirl around under the hood covering everything in a layer of oil to catch dirt and make things really disgusting.

I prefer to route the stink to aft of the transmission. No negatives in the intake to no oil + inert that is crankcase vapors.

Keep in mind that what you are considering is not ahhhh..... legal.
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Old 04-18-2012, 11:05 AM   #25
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No problems with the oil dripping and staining your driveway? Or are you using some sort of catch prior to the vent?
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