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Old 08-17-2007, 11:46 AM   #1
thornton22050
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Default weird problem ever since i built my motor

Ok i built and forged my motor and ever since i did im having a very werid problem. When we go out and make hard pulls on the highway usual lke 60 to 160 and i have my boost turned up about 25-28psi sometimes i dump alot of oil into my catch can, i was hoping you guys could check my setup and tell me if its right. there are 4 valve cover ventlines each one has its own indivual 5/8inch line that runs seprately into the catch can i never t these lines, and then i simply capped the pcv valve off completley. the way i have this setup seems fine to me but i thought i would check

by the way since i run a standalone i never put anything from the catch can back into the intake it just is open to the atmosphere
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Old 08-17-2007, 12:42 PM   #2
jays05
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Why did you set up your breather lines that way? Seems that you would build up lots of crankcase pressure.

One of the breathers on each head should go to a crankcase vent that's under the intake manifold... what did you do to that crankcase vent? Is your crankcase completely sealed right now???
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Old 08-17-2007, 01:16 PM   #3
fishheadback
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Realistically you should always be pulling vaccum from the crankcase.

During idle and manifold vaccum, the PCV pulls vaccum.

Then under postive manifold pressure the intake pulls vaccum via the turbo sucking in tons of air.
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Old 08-17-2007, 01:32 PM   #4
vica153
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The point of the lines going to the intake is so that there is vacuum help vent the crank. You've completely messed up your PCV system.

2 catch cans is the way it should be done.

1 in the vent line that goes from the crank to the intake (before the turbo)

1 for the 2 valvecover vent lines that T togther then go to the intake. (before the turbo again)

And like it was said above the other 2 valvecover vent lines should connect to the other crank vent.

Last edited by vica153; 08-17-2007 at 01:38 PM.
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Old 08-17-2007, 01:35 PM   #5
cdigerlando
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Default Venting

What does everyone think about this idea. Vent the cam covers with filters. Pull a vaccum only from the crankcase to a catch can then to the turbo suction. This should reduce the amount of blow by oil? and perhaps assist in moving oil from the heads to the pan during hard turns.

One of the problems you may be having with your built motor is that at 24 psi of boost you are creating a huge amount of suction pulling tons of oil entrained air. These are really just supposed to be vents to prevent pressure from building up. You could try also putting another filtered vent on the catch can to effectively reduce your vacuum on the engine. Don't forget, your built engine runs looser clearances everywhere. You will have more blowby in the pistons than stock, and you will have larger bearing oil clearances than stock if it was done correctly.
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Old 08-17-2007, 01:58 PM   #6
jays05
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Here is what I'm doing...

I left the crankcase breather (the one under the IM) connected to the valvecovers like stock. The other head breathers tee together and go to a lingenfelter air/oil separator. We removed the pcv valve completely, and connected that vent into the drain on the air/oil separator. The air/oil separator is connected to the intake like stock. It pulls vacuum in the crankcase, but it doesn't pull any oil into the intake. And after 2200 miles on a new built motor, with the last couple hundred miles at 20-24psi, it hasn't burned any noticable amount of oil.
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Old 08-17-2007, 02:24 PM   #7
thornton22050
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Default

Quote:
Originally Posted by jays05 View Post
Here is what I'm doing...

I left the crankcase breather (the one under the IM) connected to the valvecovers like stock. The other head breathers tee together and go to a lingenfelter air/oil separator. We removed the pcv valve completely, and connected that vent into the drain on the air/oil separator. The air/oil separator is connected to the intake like stock. It pulls vacuum in the crankcase, but it doesn't pull any oil into the intake. And after 2200 miles on a new built motor, with the last couple hundred miles at 20-24psi, it hasn't burned any noticable amount of oil.
so basicly what your saying is i instead of running my valvecover ventlines into my can indivdualy like the way that i have it i should just t them together like they were and run them into my intake?
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Old 08-17-2007, 03:07 PM   #8
jays05
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You should be doing something with the port that used to go to the pcv valve. Either put the pcv valve back on or connect that port to an air/oil separator that recirculates the oil.

Did you really cap off both crankcase vents? I think it's a good idea to leave the other head breathers connected to that crankcase vent under the intake manifold. The only reason I tee my head breathers together is because there is only one input port on my air/oil separator.

On the other hand, at 25-28psi you are pushing a lot of air through the motor... even if only 5% of that is blowby, it's still a lot of air flowing through your catch can. So oil in the catch can is normal. My setup dumps that oil back into the crankcase, so I see very little oil loss.
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Old 08-17-2007, 03:41 PM   #9
thornton22050
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Default

Quote:
Originally Posted by jays05 View Post
You should be doing something with the port that used to go to the pcv valve. Either put the pcv valve back on or connect that port to an air/oil separator that recirculates the oil.

Did you really cap off both crankcase vents? I think it's a good idea to leave the other head breathers connected to that crankcase vent under the intake manifold. The only reason I tee my head breathers together is because there is only one input port on my air/oil separator.

On the other hand, at 25-28psi you are pushing a lot of air through the motor... even if only 5% of that is blowby, it's still a lot of air flowing through your catch can. So oil in the catch can is normal. My setup dumps that oil back into the crankcase, so I see very little oil loss.
i think what my problem is since my catchcan sits above my motor and it vents to the atmoshpere there is never any suction pulling pressure out of the valve cover vent lines causing tons of pressure to build up and then finally dumpng it out of one side of the lines when there is to much. if i had it hooked up to the intake the turbo would effectively pull the pressure out crankcase through the valve cover ventlines thus never letting the pressure get to the point where so much builds up that it takes oil with it, And in my opinion having the pcv capped shouldnt matter since a properly working pcv closes under boost anyways
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Old 08-17-2007, 10:14 PM   #10
charliew
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Default pcv

PCV is very good. Oil in the intake is veeery bad. Oil in the air to the cylinders causes premature detonation.( it lowers the octane) On high mileage na motors you will find terrible oil residue inside the intake just after the throttle body. The air oil seperator is very good, it's designed for big diesel motors. The PCV valve is meant to pull bad things out of the engine especially on warm up. You don't want that stuff back in the motor.The application with all the breathers going to a catch can is ok. The idea would be to apply intake vaccum until boost and then vaccum from in front of the turbo. This needs to be done with one way valves. You don't want to drain a catch can back to the motor, thats why they use seperators. Hook up a vaccum guage to the line that goes in front of the turbo and measure the amount of vaccum at high boost 20 inches of vaccum might be good at high rpm but it'll never happen because of the blowby. Thats what total seal rings are for. There is already several good posts on how to do this. Thats what the web is for.

Charlie

Last edited by charliew; 08-17-2007 at 10:20 PM.
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Old 04-04-2010, 12:20 AM   #11
STIStalker
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Quote:
Originally Posted by jays05 View Post
Here is what I'm doing...

I left the crankcase breather (the one under the IM) connected to the valvecovers like stock. The other head breathers tee together and go to a lingenfelter air/oil separator. We removed the pcv valve completely, and connected that vent into the drain on the air/oil separator. The air/oil separator is connected to the intake like stock. It pulls vacuum in the crankcase, but it doesn't pull any oil into the intake. And after 2200 miles on a new built motor, with the last couple hundred miles at 20-24psi, it hasn't burned any noticable amount of oil.
This sounds like a good way to do it.
Anybody else using an air/oil separator hooked up like this?
I have 04 sti heads with two vent lines on top.
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Old 04-04-2010, 11:14 AM   #12
CKxx
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Your BOV sounds lame
93 RX7+09 Forester

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What else is done to the car?
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