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sluggo
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Joined: August 17, 2005
Posts: 946
Location: Portland, Or.
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 Posted: Tue Mar 14, 2006 11:49 am Post subject: Valve Cover Breather Hoses? |
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Okay, I know this is kinda wierd. I'm adding breather hoses to the valve covers. Placement in the covers has already been figured out and they will lead into the air filters.
My question is: Has anybody done this? What benefits have you seen (if any)? Can this screw anything up? What kind of hose should I use? Bottomend thinks the hoses will need to be very high temp or it will melt on the valve side. Stainless Steel?
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keifernet
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| Posted: Tue Mar 14, 2006 11:55 am Post subject: |
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Good quality oil resistant hose like used for remote oil coolers should not melt... hell even good old braided factory breather hose will not melt unless it is in very close proximity to the exposed pipe of the exhaust.
If the crankcase blow by/venting temp is hot enough to melt quality hose then you would have a major engine problem.   |
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josh
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Location: laid back in the tall grass
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| Posted: Tue Mar 14, 2006 12:53 pm Post subject: |
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| sluggo wrote: |
| My question is: Has anybody done this? What benefits have you seen (if any)? |
Volkswagen did this on 72 and later type3's, type4's and 914's.
The valve cover vents were added as part of a positive crankcase ventilation system.
On these systems air flows from the aircleaner through a flame trap, to the valve covers. The air in the crankcase ends up flowing through a pcv valve and hose into the intake air distributor.
The benefits of this system are:
Cleaner engine. Filtered air comes in. Blowby, flashed oil, carbon particulates, ect go out.
Efficiency. There is vacum being pulled on the case. Lower pressure means less air. Less air means less resistance.
Oil leak prevention. The inside of the engine is a low pressure area, so there's less pressure on the seals.
Some people also believe the air flowing into the engine from the valve covers also pulls oil that sloshes into the valve covers back into the crankcase. Makes sense to me.
Problems:
An oil leak can become a vaccum leak and contaminants may be pulled through it.
Fuel mixture will have to be recalibrated to additional incoming air.
If you do it the way VW did it I would say it's definitely worth while.
If you just put some vents in the valve covers and leave the breather as is, I don't see much benefit unless you have engine problems causing exessive blowby. In that case it's just a band aid anyway.
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| modok wrote: |
...If If stoner A takes a hit and then stoner B goes right away(not waiting two seconds), he's trying to suck on it while it's still got a vaccum, doesen't get much of a hit at all! Cause it hasn't filled back up all the way yet.
Stoner A is cylinders #2/4 B is #1/3 The plugged bowl is the throttle, the bong is the manifold |
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sluggo
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Joined: August 17, 2005
Posts: 946
Location: Portland, Or.
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| Posted: Tue Mar 14, 2006 1:05 pm Post subject: |
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| josh wrote: |
| sluggo wrote: |
| My question is: Has anybody done this? What benefits have you seen (if any)? |
Volkswagen did this on 72 and later type3's, type4's and 914's.
The valve cover vents were added as part of a positive crankcase ventilation system.
On these systems air flows from the aircleaner through a flame trap, to the valve covers. The air in the crankcase ends up flowing through a pcv valve and hose into the intake air distributor.
The benefits of this system are:
Cleaner engine. Filtered air comes in. Blowby, flashed oil, carbon particulates, ect go out.
Efficiency. There is vacum being pulled on the case. Lower pressure means less air. Less air means less resistance.
Oil leak prevention. The inside of the engine is a low pressure area, so there's less pressure on the seals.
Some people also believe the air flowing into the engine from the valve covers also pulls oil that sloshes into the valve covers back into the crankcase. Makes sense to me.
Problems:
An oil leak can become a vaccum leak and contaminants may be pulled through it.
Fuel mixture will have to be recalibrated to additional incoming air.
If you do it the way VW did it I would say it's definitely worth while.
If you just put some vents in the valve covers and leave the breather as is, I don't see much benefit unless you have engine problems causing exessive blowby. In that case it's just a band aid anyway. |
Does anyone have pics of this setup? I kinda get it but not really.
The way it is set up now (well it's in a million pieces now but normally) is that the oil breather goes into the hose that connects the two air filters on my Webers.
The fuel breather and air outlet from the fan shroud connect to the charcoal cannister and that connects to the same hose connecting the air filters.
I was just gonna run a hose from each valve cover to the same hose connecting the air filters.
Should I run it through the charcoal cannister and a PCV valve or am I just way off?
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josh
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| Posted: Sun Mar 19, 2006 7:36 am Post subject: |
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Ok, I scanned the schematic from my type4 book.
Some use a small orifice of 3-4mm instead of a PCV valve. They say this is an improvment over a pcv valve.
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| modok wrote: |
...If If stoner A takes a hit and then stoner B goes right away(not waiting two seconds), he's trying to suck on it while it's still got a vaccum, doesen't get much of a hit at all! Cause it hasn't filled back up all the way yet.
Stoner A is cylinders #2/4 B is #1/3 The plugged bowl is the throttle, the bong is the manifold |
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josh
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Joined: July 13, 2003
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Location: laid back in the tall grass
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| Posted: Sun Mar 19, 2006 7:59 am Post subject: |
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Ok, I just read one of your posts and saw that you are switching to a 914 oil fill setup with dual webers.
Most 914 oil fillers are already setup for a pcv valve.
I would install a vacum fitting into the manifolds. One under each throttle plate...
...So 4 vacum lines into one common junction with the pcv hose, connected to the pvc valve.
Connect the valve cover ports to the aircleaners.
Be sure to tune the carbs after this is all done and you should be all set.
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| modok wrote: |
...If If stoner A takes a hit and then stoner B goes right away(not waiting two seconds), he's trying to suck on it while it's still got a vaccum, doesen't get much of a hit at all! Cause it hasn't filled back up all the way yet.
Stoner A is cylinders #2/4 B is #1/3 The plugged bowl is the throttle, the bong is the manifold |
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Amskeptic
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Joined: October 18, 2002
Posts: 8568
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| Posted: Sun Mar 19, 2006 8:26 am Post subject: |
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Be careful here, sluggo. Aftermarket air-filters are not my favorite on a good day. You must absolutely guarantee yourself that the air being introduced into the valve cover area is clean clean clean clean. You also want to determine that your airflow through this breather set-up is going in the right direction which is why a positive crankcase ventilation valve is critical. Fact of the matter is, the oem breather on the Type 4 engine is more than suitable. . . particular with a nice set of piston rings properly seated.
Colin
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sluggo
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Joined: August 17, 2005
Posts: 946
Location: Portland, Or.
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| Posted: Sun Mar 19, 2006 10:26 am Post subject: |
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| josh wrote: |
Ok, I just read one of your posts and saw that you are switching to a 914 oil fill setup with dual webers.
Most 914 oil fillers are already setup for a pcv valve.
I would install a vacum fitting into the manifolds. One under each throttle plate...
...So 4 vacum lines into one common junction with the pcv hose, connected to the pvc valve.
Connect the valve cover ports to the aircleaners.
Be sure to tune the carbs after this is all done and you should be all set. |
Josh,
Thanks for the diagram! That's Perfect!
I already have the 4 manifold ports connected to one line and that leads to the one way valve and then to the brake booster.
Stupid Question(s): On the diagram, the crankcase breather leads to the Intake Air Distributor. Then the valve breathers go to a flame trap and then to the Air Cleaner. On my setup the crankcase breather goes directly to the Air Cleaner with no flame trap or PCV.
Where would the Intake Air Distributor be on my Webers? And what is a Flame Trap?
I have this oil/crankcase breather cover (Part #022 115 303 A). It has a wierd piece on top that looks like some kind of PCV valve but it blows in boths directions. Anyone know what this is?
Colin,
How do I make sure the air going into the valves is clean? Proper airflow would be towards the valves right? I thought the air cleaners sucked? How would air flow from the cleaner toward the valves if it is sucking?
THANKS EVERYONE for a ll the help!
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