Blowby Setup Question; Crank Case Vent

[Ski Bum]

I'm planning on running a blowby setup eventually. I have been looking into intake pipes that do away with all of the factory plumbing that is no longer needed. What I'm trying to figure out is what to do with the crankcase vent tube that runs into the intake pipe. I know some people just throw a filter on it and call it day but others have argued against it saying it can become a vacuum point. Is there an alternative source to plumb that vent to other than the intake pipe?

 

[fourreGsixty3]

http://www.slowboyracing.com/shop.php?sid=&cat=4138 , that teamed up with ss braided fuel line going from VC breather hole to the catch can, the filter method causes oil to be blown all over the engine bay, and make a mess of the entire EB instead of the intake pipe, the link I provided will keep both clean.

Dustin

 

[brute]

My setup goes intake manifold nipple - check valve - catch can - PCV

On the intake side of the valve cover vents, I just put one of those APC PepBoys filters.

 

[donmagicjuan]

Is there an alternative source to plumb that vent to other than the intake pipe?

The only logical location to plumb the line from the valve cover is into someplace before the turbo, i.e. the intake pipe. The reason is because under boost, the PCV valve is shut, so the vacuum generated in the intake pipe by the turbo provides the necessary force to draw out vapors from the crankcase. When off-boost, vacuum in the intake manifold permits the PCV valve to be open and recirculates blowby back into the combustion chamber to be burned.

Another alternative is an oil separator, such as RRE's no-name catch can. This is like having a catch can that is recirculated to your intake, and eliminates oil buildup in the intake while preserving the intended functionality of the PCV system. Of course, if you are hell-bent on going with an intake pipe that eliminates the return line, this is not an option for you.

 

[fourreGsixty3]

Another alternative is an oil separator, such as RRE's no-name catch can. This is like having a catch can that is recirculated to your intake, and eliminates oil buildup in the intake while preserving the intended function of the PCV system. Of course, if you are hell-bent on going with an intake pipe that eliminates the return line, this is not an option for you.

Yeah thats whats in the link I provided, I think its the best.

Dustin

 

[donmagicjuan]

Yeah thats whats in the link I provided, I think its the best.

Dustin

Are you sure? Because that one looks like their regular filter catch can. I was talking about this one: http://www.roadraceengineering.com/instructions/greddycatchcan.htm

 

[Ski Bum]

Ok, those all look like great soultions for routing the crankcase vent into the intake pipe. I have 3 questions for when it is not routed that way:

What would be the drawback (other than a dirty engine bay) of just throwing a filter on the crank case breather and not routing it into the intake?

Will the crankcase pressure build up enough and safely enough to relieve itself through the filter?

Would there ever be a risk of unmetered air entering the crankcase through the filter in a vacuum situation?

 

[donmagicjuan]

Ok, those all look like great soultions for routing the crankcase vent into the intake pipe. I have 3 questions for when it is not routed that way:

What would be the drawback (other than a dirty engine bay) of just throwing a filter on the crank case breather and not routing it into the intake?

Will the crankcase pressure build up enough and safely enough to relieve itself through the filter?

Would there ever be a risk of unmetered air entering the crankcase through the filter in a vacuum situation?

The drawback is that you will have slightly positive crankcase pressure under boost, just enough to overcome the filter. The most common side effect of excessively high pressures is a launched dipstick. However, since literally thousands of people run this type of setup, I doubt you're going to be at any real risk of causing serious damage.

The only time it would be possible to have unmetered air enter your combustion chamber through the crankcase vent is under vacuum conditions in the intake manifold. Since you will predominantly be in closed-loop operation under these circumstances, the fuel trims should be able to cancel out the effect and get you back to a stoich AFR. The worst case I suppose would be a fuel trim CEL, but I doubt anyone here has ever experienced that.

For me, it was worth the extra $10-20 to keep the system operating the way it was intended. I hope this equips you well enough to make your own informed decision.

 

[Auto RS T]

Oil will stay in the filter if you use this set-up. No dirty engine bay. Just replace every so often when it looks too dirty. This way it is going to the intake and circulating not just venting. I am interested to know if the catchcan/breather is a better way to go.

 

[fourreGsixty3]

The only real problem is the oil being blown all over engine bay, and a slight pos. pressure under boost.

Yes it will build up enough pressure, project_tsi took the VC hose and just ran it towards the ground out of the engine bay, and he has no problems doing that and that is essentially the same as the filter but with no filter and no oily engine bay.

That Greddy catch can looks pretty good, it collects the oil and keeps the stock VC recirculating into the intake pipe.

Lots of people use the RRE catch-can, but some say they can smell oil/gas from it.
In the end the decision is up to you, we just give you a little food for though

EDIT: I need a quick reply button donmagicjuan beat me to it.
Dustin

 

[Ski Bum]

I just found this on Ebay. It looks like a pretty good solution and much smaller than a full catch can.

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I'd like to run the FP cast 4" intake pipe but I don't see any sort of options for crank case vent recirculation. I suppose I could have a nipple welded in place?

 

[Irrational]

http://www.slowboyracing.com/shop.php?sid=&cat=4138 , that teamed up with ss braided fuel line going from VC breather hole to the catch can, the filter method causes oil to be blown all over the engine bay, and make a mess of the entire EB instead of the intake pipe, the link I provided will keep both clean.

Dustin

$60 Buck's!!!!! Who are they kidding they took a JAZ Catch can and dubbled the price and called it slowboy hahaha.

 

[dedlewamp]

Also, if you're looking for another alternative. Most tool stores carry an oil separator that is designed to be used with compressed air. I've seen the smaller ones go for right around $20.00. Just a thought. . .