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How to do the boosted car crankcase breathing right

 
Old 04-05-2016, 05:38 PM
  #166  
FredR
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Originally Posted by ptuomov View Post
Fred --


There's one modification to your system that might eliminate the last drops of oil from the ProVent. Currently, your oil-filler neck breather port is at the front-bottom of the filler neck. (Mine was in the same spot in the previous version.) We're moving that to the side in this new version. The reason why we're moving it to the side is that during deceleration, a small amount of oil that's in the filler neck gets thrown to the front of the neck and possible from there to the vent hose if the vent hose is connected to the front bottom. The new version will vent from the sides of the oil filler neck, a little further back than the oil filler cap.
Tuomo,

Did actually consider something along those lines during the first Pro vent incarnation. One possibility was to drill a hole through both sides and stick a tube bridging both sides with the top quadrant cut out to vent gas but not collect any free flowing oil sloshing around in there.

In the end it was the path of least resistance as John was able to supply a nozzle, a hose to carry the oil away and - wait for it- a bung to shove down the nozzle to permit oil fill and avoid pouring the stuff straight into the Pro vent- you just have to remember to remove it after filling assuming you can find it in the first place!

The packaging is neater this way but as you say there may be a little tendency to collect oil when braking in real anger if the baffle does not take it all out as we suspect it does at the moment. Similarly the packaging may be a bit more tricky from the side- doubtless doable but not so sure how it would look.

Rgds

Fred
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Old 04-16-2017, 06:34 PM
  #167  
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A quick update on the boosted motor crankcase breather system in the below video at the 12 minute mark:

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Old 03-28-2018, 09:50 PM
  #168  
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Default Another idea for a crankcase evacuation system for a turbo car.

Are the operating principles obvious?



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Old 03-29-2018, 09:56 AM
  #169  
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Is the jet pump an off the shelf item?
Thanks,
Dave
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Old 03-29-2018, 11:48 AM
  #170  
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Originally Posted by [email protected] View Post
Is the jet pump an off the shelf item? Thanks,Dave
I think the 928 brake boost venturi jet pump could be used. One would also need a t-fitting, one check valve (as the other is built into the venturi jet pump), and two calibrated metering orifices. The main uncertainty about this reuse of a component would be whether the 928 venturi jet pump can handle a little bit of oil.
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Old 03-29-2018, 01:23 PM
  #171  
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using pressure from intercooler to make a jet that draws in valve cover vapors to eject to the manifold?

but why check valve to compressor inlet? wouldn't it make sense to put the check valve on the plenum side, so that when plenum is in boost the vapor flow goes to the compressor inlet?
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Old 03-29-2018, 02:30 PM
  #172  
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Originally Posted by V2Rocket View Post
using pressure from intercooler to make a jet that draws in valve cover vapors to eject to the manifold? but why check valve to compressor inlet? wouldn't it make sense to put the check valve on the plenum side, so that when plenum is in boost the vapor flow goes to the compressor inlet?
The main operating modes:

Part throttle, no boost. Compressor inlet at atmospheric pressure, intercooler bottom tank at atmospheric pressure, intake manifold at a vacuum. Intake manifold vacuum pulls air from the intercooler bottom tank, and the venturi jet pump pulls a vacuum in the crankcase. The check valve prevents air from being pulled from the compressor inlet.

Full throttle, no boost. The check valve in the compressor inlet has a cracking pressure of something like 5 psi. This means that the path to compressor inlet will remain closed. There's some limited flow from intercooler end tank to intake manifold, but the system is mostly inactive.

Full throttle, full boost. The intake manifold and intercooler bottom tank have similar pressure, with the intake manifold slightly lower because of piping flow restriction. There's a big pressure differential between the compressor inlet and intercooler end tank, and that opens the check valve. Boost is being wasted back to the compressor inlet, but that's ok as above 5psi there's room to waste some. The benefit is a strong crankcase vacuum.
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Old 03-29-2018, 08:11 PM
  #173  
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If you'd really want to simplify this venturi jet pump idea for a supercharged or turbo car, simply plumbing a break booster venturi jet pump from compressor inlet to compressor outlet and connecting the vacuum port of the venturi jet pump to the crankcase breather port would work. One would just have to play with a restrictor in the compressor outlet port to calibrate the vacuum and the flow. This would bleed off a little bit of boost but pull a nice vacuum into the crankcase at high rpms and load.
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Old 03-31-2018, 10:23 AM
  #174  
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Simplest setup:


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Old 03-31-2018, 11:44 AM
  #175  
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that one i like.
think there's a need for a check valve to valve cover despite having the venturi?
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Old 03-31-2018, 12:17 PM
  #176  
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Originally Posted by V2Rocket View Post
that one i like.
think there's a need for a check valve to valve cover despite having the venturi?
If you use the standard Venturi jet pump from brake booster, it has that check valve built in already.
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Old 05-28-2018, 02:42 PM
  #177  
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Default Still dry

The breather system in the car has been run on the dyno a lot now, breather hoses completely dry of oil. Only water vapor coming out of the crankcase after passing thru the baffles and separators. No extreme g-force testing yet.
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