Crankcase Ventilation via the exhaust
As mentioned in BenFenner's thread about crankcase ventilation, a method of removal of positive crankcase pressure would be to route it to the exhaust.
Have any of you done this? What were your results at wide open throttle? Were you running an exhaust without a muffler and cat?
I am reading into this more and it seems that there's a potential issue with positive crankcase pressure being developed at WOT and higher RPMs. I'm guessing this is due to too much restriction in the exhaust negating the scavenging venturi effect. For those of you that have done this on SR20s, have you seen positive crankcase pressure at WOT, or have you maintained a vacuum throughout the rev range with partial and open throttle?
I really want to do this, as it seems the best available method for the money:
With an oil seperator combined with this method, you:
- don't lose oil
- there is no oil smoke in the exhaust from burning oil vapor
- if vacuum is maintained through the rev range (this is the area I'm wondering about) you could potentially have better vacuum than the stock method of routing it back through the intake
- related to the point above, you could potentially have better ring seal than stock, compounding the benefits of less blowby and better compression
The obvious best options aside from this available are the wet or dry sump mechanical vacuum pump setups... which can cost you a pretty penny.
With just an oil separator/catch can added to the line going back to the intake, it would be beneficial, but as mentioned in Ben's thread, there'd be no benefit to promoting ring seal. Cleaner intake, less chance of detonation, but nothing to do with improving ring seal.
Venting to exhaust, if vacuum can be maintained throughout the rev range... would be ideal IMO. A best bang for the buck setup.
Have any of you done this? What were your results at wide open throttle? Were you running an exhaust without a muffler and cat?
I am reading into this more and it seems that there's a potential issue with positive crankcase pressure being developed at WOT and higher RPMs. I'm guessing this is due to too much restriction in the exhaust negating the scavenging venturi effect. For those of you that have done this on SR20s, have you seen positive crankcase pressure at WOT, or have you maintained a vacuum throughout the rev range with partial and open throttle?
I really want to do this, as it seems the best available method for the money:
With an oil seperator combined with this method, you:
- don't lose oil
- there is no oil smoke in the exhaust from burning oil vapor
- if vacuum is maintained through the rev range (this is the area I'm wondering about) you could potentially have better vacuum than the stock method of routing it back through the intake
- related to the point above, you could potentially have better ring seal than stock, compounding the benefits of less blowby and better compression
The obvious best options aside from this available are the wet or dry sump mechanical vacuum pump setups... which can cost you a pretty penny.
With just an oil separator/catch can added to the line going back to the intake, it would be beneficial, but as mentioned in Ben's thread, there'd be no benefit to promoting ring seal. Cleaner intake, less chance of detonation, but nothing to do with improving ring seal.
Venting to exhaust, if vacuum can be maintained throughout the rev range... would be ideal IMO. A best bang for the buck setup.
Last edited by wildmane
on 2014-01-04
at 02-11-12.
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