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for anyone that has crankcase pressure issues

 
Old Oct 13, 2013, 03:04 AM
  #766  
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i guess using the rear o2 bung is out of the question since it has no angle.
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Old Oct 13, 2013, 10:31 AM
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Yea i believe they have to be at a 45*... And i know on race cars they are in the header itself... Mine is about a foot back in the downpipe and i thought it was to far...
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Old Oct 13, 2013, 11:22 AM
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What about less than a 45.. Closer to parallel with flow. Would that draw more vacuum ?
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Old Oct 13, 2013, 04:19 PM
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only one way to find out... i didnt develop the technology... i just use it...
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Old Oct 13, 2013, 06:57 PM
  #770  
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Well, I learned a bunch of stuff today. First of all, an air check valve is needed for the exhaust scavenging system to work, however, its still a fairly weak vacuum 99% of the time. The only circumstance where I was able to momentarily generate more than 1 psi of vacuum was for a split second during throttle lift when the slug of exhaust would pull a vacuum behind it as it exited the exhaust pipe. At idle and cruise, it was around -0.5 psi whether I used the interrupt or the whistle configuration. I also tried an alternate configuration that might have generated another 0.25 psi of vacuum, but so what.

Here's the kicker. I decided to try to compare the amount of air that the scavenging system could pull to the amount of air coming out of the crankcase. With the scavenging system hooked up to the PCV port, at idle there was still positive gas flow coming out of the crankcase vent (the vent that would go to the air intake). So that means that the scavenging can't keep up with the amount of blowby being generated, at least at idle. Perhaps a slightly stronger vacuum is created by the scavenging system during cruise, but I'm sure the amount of blowby is also increasing as well. So while a little bit of vacuum on one of the valve cover ports doesn't hurt anything, its certainly not helping in any signficant or even insignificant way with crankcase ventilation. The real goal is to be able to pull fresh air into the crankcase, but its definitely not doing that.

At this point, I think that even the amount of fresh air pulled in by the stock Evo PCV system is rather minor from the perspective of helping to remove contaminants from the oil. It does pull a light vacuum on the port that goes to the intake pipe, but its a very light amount of flow into the crankcase. My conclusion is that blowby is its own best source of continuous crankcase ventilation, and plumbing the valve cover with a couple of big hoses that either go to a catch can or go right to the ground is as good as anything else.

Last edited by mrfred; Oct 16, 2013 at 05:41 PM.
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Old Oct 14, 2013, 07:55 AM
  #771  
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joseph or tt240z, with the scavenge line hooked up to the valvecover, could you ziptie a plastic bag over the other valvecover vent line to observe whether it fills up or deflates at idle? tt240z, could you cap off the 3rd vent line on your setup?
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Old Oct 14, 2013, 09:17 AM
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Originally Posted by 240Z TwinTurbo View Post
When I have time I will data log the use of various ports...exhaust scavenge, turbo inlet, 1 vs 2 -10AN's, etc.





Holy busy engine bay, god damn! Looking forward to your results!
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Old Oct 15, 2013, 08:45 AM
  #773  
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Hey fred... Just saw your lil post in there... I'll let you know in a bit
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Old Oct 15, 2013, 08:15 PM
  #774  
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Originally Posted by mrfred View Post
joseph or tt240z, with the scavenge line hooked up to the valvecover, could you ziptie a plastic bag over the other valvecover vent line to observe whether it fills up or deflates at idle? tt240z, could you cap off the 3rd vent line on your setup?
Just to clarify my setup...

I have two -10 an lines running to the sealed can from the valve cover
1 line to the turbo inlet
1 line to the exhaust scavenge

What are you exactly requesting? What are you referring to when you say 3rd vent line?
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Old Oct 15, 2013, 08:34 PM
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Originally Posted by 240Z TwinTurbo View Post
Just to clarify my setup...

I have two -10 an lines running to the sealed can from the valve cover
1 line to the turbo inlet
1 line to the exhaust scavenge

What are you exactly requesting? What are you referring to when you say 3rd vent line?
Leave the exhaust scavenge hooked up, cap off two of the other three lines, and then use a zip tie or rubber band to seal a partially inflated quart size bag up to the third port. Watch whether the bag inflates or deflates while the car is idling. The idea is to determine whether the exhaust scavenge is actually pulling fresh air into the head.
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Old Oct 16, 2013, 04:23 PM
  #776  
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240Z - how much oil do you kick out your Hals cap? Running both metal plate baffle and inner baffle? I toss a fair amount out of mine; I'll post pics when my new setup is done. Do you also have the valve cover tranny side breather plugged or are you venting it? Pic looks like its capped/plugged.
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Old Oct 16, 2013, 05:47 PM
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Has anyone tried using a road draft tube or setting up a venturi tube to pull a vacuum while the car is moving? A few simple calculations I did last night suggest that moving at 30 mph could generate ~2 psi of vacuum using a venturi tube. I may try a venturi tube tomorrow.
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Old Oct 16, 2013, 06:13 PM
  #778  
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Originally Posted by boostedwrx View Post
240Z - how much oil do you kick out your Hals cap? Running both metal plate baffle and inner baffle? I toss a fair amount out of mine; I'll post pics when my new setup is done. Do you also have the valve cover tranny side breather plugged or are you venting it? Pic looks like its capped/plugged.
It kicks out a fair amount, which is annoying on a daily driver. Tranny side vent is currently plugged, but will be used to measure crankcase pressure when I get around to logging it. Depending on the crankcase data I hope to be able to ditch the HAL cap and run the single -10 from Fairclough.
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Old Oct 17, 2013, 05:46 PM
  #779  
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Interesting that this thread has turned into an actual science project...
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Old Oct 18, 2013, 12:41 AM
  #780  
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well its either pplay and learn in this one... or answer 10 posts a day on how many quarts does the tcase hold... or how do i change my air filter...

when evom was a lil baby of a forum there weren't so many dtupid questions... it was knowledgeable posts... and some not so knowledgeable... like i took apart my diff for fun... and found the plates out of order!!!! i'm only ever on anymore because it becaem part of my life... now i open safari and immediately come to evom only to find nothign has changed... most members are retarded... nobody has updated anything new or important... and Mrfred is still the smartest most randomly experimental person i have ever not actually met... but met.
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