What's the easiest way to avoid pressure in the crank case?
09-23-2005, 09:25 AM
#21
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Join Date: Nov 2003
Posts: 0
Re: What's the easiest way to avoid pressure in the crank case?
1-." blowy by is pressure moving UP past your rings in to the head, not moving down from the head in to the crank case which is what it sounds like you're thinking."
blow by is pressure that is forced by the rings it cant go strait into the head unless you have a hole in you cyl heads combustion chamber, if it leaks past the valves then it goes into the exhaust or intake manifold. It has to go past the rings nothing else for blow by. Then when were past the rings were in the crank case which is conected to the vavle cover with the oil drain back holes. If you take a blow gun and blow it in your dip stick tube weres it going to come out? The breather hole in the vavle cover.
2 -"crank case pressure is from moving parts in the rotational assmebly (mostly the bottom of the pistons) pumping up and down so fast creating pressure inside the crank case, which if too great, will blow up past your rings."
2 pistons go up 2 pistons go down when rotating they cancel each outhers displacment out creates turbulance not pressure
3- which if too great, will blow up past your rings.
the crank case presser would have to be huge to go from crank case up past the rings, you have say 180 psi in the combustion chamber just cranking it over never mind in the power stroke and crank case pressure is going to be more so it can over come this and blow backwards past the rings no
4- " he asked what the best way to avoid crank case pressure was, and the easiest way is to open up the crank case vent tube and let the pressure vent out of there."
I agree and I also run a catch can on my current car but I have also run pcv's on my other cars because it doesn't hurt anything.
5-"the health of a motor has nothing to do with this."
the ******* the rings the more blow by, the better the crank case ventalation you need
blow by is lost compression past the rings during combustion in the cyl nothing else which ends up in the crank case/valve cover area :P
blow by is pressure that is forced by the rings it cant go strait into the head unless you have a hole in you cyl heads combustion chamber, if it leaks past the valves then it goes into the exhaust or intake manifold. It has to go past the rings nothing else for blow by. Then when were past the rings were in the crank case which is conected to the vavle cover with the oil drain back holes. If you take a blow gun and blow it in your dip stick tube weres it going to come out? The breather hole in the vavle cover.
2 -"crank case pressure is from moving parts in the rotational assmebly (mostly the bottom of the pistons) pumping up and down so fast creating pressure inside the crank case, which if too great, will blow up past your rings."
2 pistons go up 2 pistons go down when rotating they cancel each outhers displacment out creates turbulance not pressure
3- which if too great, will blow up past your rings.
the crank case presser would have to be huge to go from crank case up past the rings, you have say 180 psi in the combustion chamber just cranking it over never mind in the power stroke and crank case pressure is going to be more so it can over come this and blow backwards past the rings no
4- " he asked what the best way to avoid crank case pressure was, and the easiest way is to open up the crank case vent tube and let the pressure vent out of there."
I agree and I also run a catch can on my current car but I have also run pcv's on my other cars because it doesn't hurt anything.
5-"the health of a motor has nothing to do with this."
the ******* the rings the more blow by, the better the crank case ventalation you need
blow by is lost compression past the rings during combustion in the cyl nothing else which ends up in the crank case/valve cover area :P
09-23-2005, 11:31 AM
#22
1.0 BAR
Join Date: Nov 2004
Posts: 319
Re: What's the easiest way to avoid pressure in the crank case?
Originally Posted by highroller54
2 -"crank case pressure is from moving parts in the rotational assmebly (mostly the bottom of the pistons) pumping up and down so fast creating pressure inside the crank case, which if too great, will blow up past your rings."
2 pistons go up 2 pistons go down when rotating they cancel each outhers displacment out creates turbulance not pressure
2 pistons go up 2 pistons go down when rotating they cancel each outhers displacment out creates turbulance not pressure
09-23-2005, 12:27 PM
#23
0.5 BAR
Join Date: Sep 2005
Posts: 150
Re: What's the easiest way to avoid pressure in the crank case?
your all wrong its based on an ancient practice call PFM (pure ------- magic) J/K
From what I understand the pcv valve is located in the valve cover itself
on idle and off idle it vents/ at throttle the intake is suppose to create vaccum enough to take over venting.
If you put your finger by the valve while idleing you can feel the pulses now when you rev it up it should stop
We from our DSM days always ran a filter on the pcv and a guard underneath to keep oil from getting on the exhaust
Now I guess if you want to be professional you can simply build a catch can. but oil will come out due to the pressure and the fact that most pickups for pcv are directly over an oil return (back to the crankcase from the head) As long as your pcv valve is good it will vent on its own without vaccuum, under boost and of course at idle. This is just my knowledge what I've seen and used Oh and depending on the filter don't be scared if it sounds like a cricket is under your hood when you first start up. Hope this helps and please don't shoot the messenger.
From what I understand the pcv valve is located in the valve cover itself
on idle and off idle it vents/ at throttle the intake is suppose to create vaccum enough to take over venting.
If you put your finger by the valve while idleing you can feel the pulses now when you rev it up it should stop
We from our DSM days always ran a filter on the pcv and a guard underneath to keep oil from getting on the exhaust
Now I guess if you want to be professional you can simply build a catch can. but oil will come out due to the pressure and the fact that most pickups for pcv are directly over an oil return (back to the crankcase from the head) As long as your pcv valve is good it will vent on its own without vaccuum, under boost and of course at idle. This is just my knowledge what I've seen and used Oh and depending on the filter don't be scared if it sounds like a cricket is under your hood when you first start up. Hope this helps and please don't shoot the messenger.
09-23-2005, 02:44 PM
#25
1.0 BAR
Join Date: Nov 2004
Posts: 319
Re: What's the easiest way to avoid pressure in the crank case?
^ ok why do you keep sayin PVC? 
NAsucks is right...N/A at WOT = 0 but crank pressure is positive = PCV vent on its own.
FI under boost = positive pressure = PCV forced closed = NO VENTING positive crank pressure from pcv system.
NAsucks is right...N/A at WOT = 0 but crank pressure is positive = PCV vent on its own.
FI under boost = positive pressure = PCV forced closed = NO VENTING positive crank pressure from pcv system.
09-23-2005, 06:50 PM
#27
1.5 BAR
Join Date: Feb 2005
Posts: 691
Re: What's the easiest way to avoid pressure in the crank case?
I saw this mentioned above and it's partially how the saab system works, but why not just carry a line to the turbo inlet? That always sees vaccum and it's pretty damn simple.
09-23-2005, 07:32 PM
#28
0.5 BAR
Thread Starter
Join Date: Jul 2005
Posts: 134
Re: What's the easiest way to avoid pressure in the crank case?
lol, stop the cat fights.
So can I just put off the tube on the vavle cover and be done with it? Or do I have to cut it at a certain place and aim it up or something so oil doesn't come flowing out.
So can I just put off the tube on the vavle cover and be done with it? Or do I have to cut it at a certain place and aim it up or something so oil doesn't come flowing out.
09-23-2005, 08:35 PM
#29
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Join Date: Nov 2003
Posts: 0
Re: What's the easiest way to avoid pressure in the crank case?
Originally Posted by topspeed
Originally Posted by highroller54
2 -"crank case pressure is from moving parts in the rotational assmebly (mostly the bottom of the pistons) pumping up and down so fast creating pressure inside the crank case, which if too great, will blow up past your rings."
2 pistons go up 2 pistons go down when rotating they cancel each outhers displacment out creates turbulance not pressure
2 pistons go up 2 pistons go down when rotating they cancel each outhers displacment out creates turbulance not pressure
