I'm looking for the best way to reroute my Crank Case Vent into the exhaust in order to get the proper vacuum. Has anyone done this? If so, can you describe your method and the results from it? I've got some ideas in mind but I wanted to see what has worked and what hasn't. Pictures would be helpful as well if possible. Thanks!
Yea I would be pretty concerned that your exhaust could push it into the crankcase. You would need a true venturi in the exhaust to ensure that it would not present a issue.
The term "venturi" is referring to a constriction or change of cross sectional area in a pipe that causes a pressure reduction. Since you want the crank case vapors to flow into the exhaust - instead of being forced with exhaust gases back into the valve cover - an attempt is made to lower the pressure at the point that the ccv is introduced. The problem is the math.
CCV pressures are low. Really low. Like a fraction of a psi low.
I don't know what the exit pressures of a 6.0 exhaust are, specifically, but exit exhaust pressures that I have measured for automotive diesel programs that I have worked on have always been in the 6-8psi range. I also don't know that those pressures could be venturied down enough to cause a ccv vacuum without causing excessive backpressure in the upstream exhaust circuit.
The bigger thing is the "why?" question. I mean... I understand the 30,000ft. attraction of having the crap exit the vehicle at one point. ...but the vapor isn't being destroyed or anything. It is just being mixed.
A separate ccv hose to exit right next to the exhaust tip is the safest. ...or it could be plumbed it into the pipe just ahead of the tip, maybe. Anything further up and I would be concerned that the gases are going to be going the direction that everyone wants. In that case, someone would need to introduce their constriction and measure the pressure that they have created at their ccv inlet to know that they will have a vacuum.
Just my two pesos. If anyone sees a problem with my logic, please point it out.
So your CCV reroute is venting to the atmosphere I take it? Most people do this it seems. My logic behind this I suppose is that the stock CCV tube is directed back into the intake where the turbo is pulling the oil vapor from the crank case into the turbo with the air from the intake. I would like to replicate that pull, just not into my brand new turbo, CAC pipes, intercooler, and intake. I attempted the catch can approach but it seems as if this is pressurizing my crank case enough to cause a slight oil leak in the exhaust side of my turbo. I believe my setup is a restriction and the white smoke validates that when the can is on. When it's off, no smoke. So, I guess the question is, exactly how important is the crank case vacuum? I want the system to work the way it's supposed to without blowing oil through my air system. The exhaust flow seems to be the only way to regain the appropriate vacuum since exhaust flow should be the same on the way out as it would be on the way in on the intake side, just in the opposite direction... The exhaust would pull the oil vapor out and help dilute it while helping to mask the smell in my perfect little scenario, I suppose. Lol I dunno... There's gotta be a way... Maybe it's ridiculous, but there still has to be way.
So your CCV reroute is venting to the atmosphere I take it? ... The exhaust would pull the oil vapor out and help dilute it while helping to mask the smell in my perfect little scenario, I suppose. Lol I dunno... There's gotta be a way...
Mine *is* venting to the atmosphere. I agree that it is unlikely that the vacuum that exists at my outlet precisely matches that of the intake. ...but, I would bet that it is closer to that than what an inlet to the exhaust would provide. It would be great to measure the vacuum at the CCV inlet to the intake and then know precisely. In that case, a small inline blower might match the intake vacuum at the CCV *and* set up a positive pressure at the exhaust inlet.
Very interesting about the catch can causing head loss. Makes sense, of course. I was considering installing one and rerouting back to the intake but had not been thinking about the loss through the different unit. Interesting.
I understand way better your motivation. I did not intend to be specifically critical of you. Part of my thinking is that I would not expect CCV vapors mixed inline with the exhaust gases to smell much different than dumping at or near the tip.
Tying into the exhaust directly is just one of those things that seems appealing in the "Wouldn't it be great if..." sense but isn't so well matched at the lower level.
So my theory stems from the whole "engine = air pump" factor. Correct me if I'm wrong here, but wouldn't the exhaust velocity match the intake air velocity very closely? If that is the case, wouldn't exhaust velocity be able to provide the same pull out as the turbo would pull in? I mean cold air should be passing through the cold side of the turbo at the same velocity as the exhaust would be passing through the hot side, right?
Yes. Ignoring the wizardry of the combustion chemistry, the mass volume might match up. But, consider what you are trying to do to your engine/pump.
Let's say we are using a shop vac to represent your engine. Air in=air out. You want to get rid of chewing tobacco. Do you spit it into the inlet or the outlet? Even if you add a hose to the outlet and cut a hole in the side of the outlet hose (exhaust), spitting into it is going to take considerable more effort that spitting into a hole cut into the inlet hose (intake). Any added head loss downstream of your exhaust-side spit hole (CAT, muffler, pipe bends, ...) is going to increase the opposing flow and further complicate your spitting endeavor.
The flow is working for you at the intake. Not at the exhaust, unfortunately.
Theory part deux... If I fabricated an exact copy of the factory CCV tube that goes into the intake out of steel and welded it into the exhaust pipe in the exact same position as it would be positioned in the intake (except on the side of the pipe instead of the bottom), the air velocity pushing out of the exhaust should do the same thing as the intake would do pulling in....
Edit: I actually think it'd work better to reverse the position of the CCV tube in the exhaust pipe... Passing exhaust would help pull the oil vapor out.
The pipes are different diameters and the gases are very different densities. But... that is definitely going in the right direction.
I would say instead: Make your adapter as described and measure the vacuum that it delivers. Compare that to the vacuum that exists at the intake CCV inlet.
The issue here is matching pressures. It may require an exhaust pipe mod that changes the cross-sectional area.
Then, after you establish a component that provides a matching pressure, sell that gahoozal an make a bunch o'money! Seriously.
That doesn't sound like a bad idea, actually. I'm in your neighborhood when I visit CAT. I expect to be that way after the first of the year.
I have a measurement-grade pressure sensor that would work fine for this. That, a power supply, and recorder - all of which I have - and we have good measurements off of the CCV inlet tube and an exhaust tap.
Let's stay in contact on this.
The OP was saying that there were some issues of the pressure drop across the filter that he had. The Racor unit might be lower head loss. ...but it is not cheap, by any means.
True, its not cheap, but it was designed for large diesel engines, for this exact purpose.
Marine diesels are just about all turbo charged, or twin turbos, and are run much harder than our engines, for much longer periods.
These Racor units are installed on just about every large Sportfish boat (Viking, Ocean, Albermarle, Jarret Bay, etc) I have ever seen.
While it is true that they were designed for this exact purpose, the OPs comment - and I don't disagree - was that catch cans may not be right for this particular application. The 6.0 could've been designed with the head loss of a catch can in mind, but it wasn't.
Knowing nothing more than I know right now... I do think that - if a 4"/5" diameter exhaust pipe insert with CCV inlet could be designed that duplicates the pressure of the intake - that could be a nice thing. If it approached the cost of the Racor, of course, it would be less valuable of a solution.
Exactly! That was why I was saying that even a small inline blower in the CCV tube might be needed. The challenge is whether the CCV exhaust inlet tube and the surrounding insert tube geometry can create the needed vacuum naturally.
My concern with the exhaust tube idea would be at low flow conditions where the exhaust velocity may not be high enough to induce vacuum.
If you had sufficient filter media and surface area, a ccv filter would work great. If it weren't for the CAC system getting filled with oil, the ccv reclamation process really wouldn't bother me. The oil burns just like fuel in the cylinders, but when it falls out of suspension and condenses is when it really makes the mess.
Yup. I already ate the $350 on my first attempt. If I buy that thing (and I'm sure it works fine), I'm pushing almost a thousand bucks for catch cans... The 15ft of 1" ID heater hose I bought last week cost $40. That's going to be my temporary solution until I get a viable exhaust CCV in place. My truck's just too awesome for those little hoses I had on that little can. Lol
Good luck on your endeavor. However this has been beat to death a hundred times on every forum, and almost always ends up being too expensive for what it does. Run a 4 foot piece of hose to the atmosphere like a Cummins or any other big truck I've ever driven. Done. On to the next mod. :smile2:
I certainly get the Zen of this, but not sure about the "beat to death" part. Not anywhere have I seen a single proper measurement of intake vacuum or exhaust pressure. To me, that means that there has been a lot of talk, but not much action. People throwing a bunch of pretty braided hoses at it - but not knowing where the gases are going - doesn't count.
I have exactly Merc's setup. It's a bit smelly for my tastes, but otherwise fine. If I could've bought a $25 fitting to punch into my exhaust to route to that guaranteed proper flow, I would've. That's my thinking.
Beyond that, I'm always up for a good engineering implementation.
Ran a Racor CCV 4500 for a while worked great on stock injectors. Got rid of it after upgrading and just ran a hose straight down to the driver's wheelwell, works for me.
Guru... I've seen some threads on this too. This thread was originally intended to seek out the results from people that have tried it, whether good or bad. I'm just trying to learn from the setups that people have proven didn't work and put together a plan out of the setups that did. Hopefully we get some feedback here from folks who have gone down that road so we can learn from their experiences. If it turns out to be all bad results, then I will rule it out and move onto the next mod. Trust me, I understand what you're saying. I just know that there has to be a way to do this effectively. Surely someone out there has done this. If I'm beating the proverbial dead horse, then I apologize.
If I have to tear mine down again I will consider it.
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