[urq] Too much Crankcase ventalation?

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Dave
A proper crankcase>valve cover oil vapor PCV system, won't suck oil,  there 
shouldn't enough vacuum to do so.  IME, oil from launches is a  problem innate 
to the v8's and S cars with the PCV breather  hoses at the back of the head.  
PCV pickup and/or vent should be  dead center in a cam cover to avoid the hard 
launch and hard braking  sloshing of oil.  The reason for a tie-in of the 
crankcase ventilation with  the valve cover, is exactly to act as a dead-air oil 
return chamber  for crankcase oil.  IMO, the 5k's with the double walled valve 
cover had a  better design for PCV than either the later flagship v8's or the 
Scar.
 
Regardless, the urq has the same basic system as the 5k's, without the  
problem of oil sloshing.  Ben's issue is strictly too much vacuum  IMO.  To fix the 
S-car or v8 problem of oil sloshing in the valve cover, it  should be pretty 
easy to install a traditional ball type PCV valve and gasket  dead center in 
the valve cover, with the vent line placed on top too.
 
SJ
 
 
In a message dated 9/4/2007 8:58:00 P.M. Central Daylight Time, Djdawson2  
writes:

I would  agree that the noise you are hearing is air being sucked past seals. 
  Idle = high vacuum = noise.  Revs higher = low/no vacuum = no  noise.

I guess recirculating crankcase gasses is an option, but I don't  see it as a 
requirement.  A catch-can is an OK solution, but if you use  the car 
aggressively, it will fill fast.

Even an AAN engine, with its  windage tray, will push a very large amount of 
oil through the breather system  during an aggressive launch.  No good.

I don't know if I'd want to  make a project out of properly sizing the 
breather system.  To me, a good  solution involves a breather device that allows the 
oil to return to the  crankcase.

If you've built an engine with serious performance potential  in mind, no 
matter how good the system works, you're going to be pushing a lot  of oil 
through it... not just gasses.  To me it was only important to  properly vent the 
crankcase, and return the out of control oil flow back to  where it belongs... 
the pan.

Unless you redesign around some of the  limitations inherent in the stock oil 
supply system, I think that a PCV  approach will always leave you with oil in 
places that you don't want it...  FWIW.

Dave


 



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