Crankcase Breather for newer cars pushing high horsepower?

[UGASpike]

Looking through search here on BITOG and could not find any *newer* information on this topic regarding newer cars pushing high horsepower/high boost so wanted to make a post.

Could anyone school me on the purpose of these crankcase breather that replace the oil fill cap?

Seen a claim that it reduces oil blow by (decreased pressure obviously), oil aeration, and minimized pressure differential working against pistons. How accurate is this in daily driving? Or is this typically seen on track cars?

I’m not sold on one but just curious

 

[KGMtech]

The old pre 1960's cars that vented crankcase pressure to the air via a tube or open ports on the rocker covers would not meet the EPA standards for emissions. Starting in 1961's the PCV valve forced the fumes to be consumed in the engine intake stroke and be burned in the engine. You would get a check engine light if your new car had the PCV system disconnected or plugged.

 

[UGASpike]

The old pre 1960's cars that vented crankcase pressure to the air via a tube or open ports on the rocker covers would not meet the EPA standards for emissions. Starting in 1961's the PCV valve forced the fumes to be consumed in the engine intake stroke and be burned in the engine. You would get a check engine light if your new car had the PCV system disconnected or plugged.

More so speaking on something pictured below. Not a PCV breather, I have a catch can on my truck which replaced the OEM PCV and I will say I have caught a lot of gunk over the last 16k miles.

 

[Adkcedarman]

Looking through search here on BITOG and could not find any *newer* information on this topic regarding newer cars pushing high horsepower/high boost so wanted to make a post.

Could anyone school me on the purpose of these crankcase breather that replace the oil fill cap?

Seen a claim that it reduces oil blow by (decreased pressure obviously), oil aeration, and minimized pressure differential working against pistons. How accurate is this in daily driving? Or is this typically seen on track cars?

I’m not sold on one but just curious

I could be wrong, but i believe these are completely unnecessary on a modern street vehicle with a Positive Crankcase Ventilation valve, a PCV.

 

[CleanSump]

Just fix the cause of excess blowby instead of applying bandaids.

 

[Lawnman23]

More so speaking on something pictured below. Not a PCV breather, I have a catch can on my truck which replaced the OEM PCV and I will say I have caught a lot of gunk over the last 16k miles.

View attachment 351354

This type of setup, replacing the oil fill cap with a filter, makes no sense. In modern PCV systems, the fresh/filtered air is pulled in from the air intake tube, post engine air filter.

There is no reason to add another filter to "offset" crankcase pressure due to boost.

 

[UGASpike]

This type of setup, replacing the oil fill cap with a filter, makes no sense. In modern PCV systems, the fresh/filtered air is pulled in from the air intake tube, post engine air filter.

There is no reason to add another filter to "offset" crankcase pressure due to boost.

This on particular is a one way breather to let pressure out not in.

I see no point in it but was curious to what the benefits would be… which seams few and far between lol.

 

[Lawnman23]

This on particular is a one way breather to let pressure out not in.

I see no point in it but was curious to what the benefits would be… which seams few and far between lol.

The entire point of having forced induction is to create boost in the intake track. Installing a breather to vent/purge that boost is some smooth-brain line of thinking

 

[jkasch]

So, I guess everyone would disagree with Grok’s assessment. (I added the Hellcat reference for my own interest).
https://grok.com/share/c2hhcmQtMi1jb3B5_cde10b73-7f45-4b58-8c8d-1649fed8a8d7

 

[Mainia]

In the Hyundai/Kia tuner community, some people over 25-26+ psi have had seal blow outs and the fix is the filter/relief on the custom oil cap. I question if the PVC tube ID is too small or there maybe a need for a dual PVC valve for more flow/less restriction.

 

[Lawnman23]

In the Hyundai/Kia tuner community, some people over 25-26+ psi have had seal blow outs and the fix is the filter/relief on the custom oil cap. I question if the PVC tube ID is too small or there maybe a need for a dual PVC valve for more flow/less restriction.

How much boost over stock is that?

 

[Mainia]

How much boost over stock is that?

8 psi more at 25 psi.

 

[Lawnman23]

8 psi more at 25 psi.

Pondering out loud here, I’m wondering if that 8 psi would then be negated by the additional venting of crankcase pressure?

I’m no forced induction expert, seems like there should be a better way be able to utilize the boost without having to bleed it off at the same time via a vent?