Atomic,

In that High-load situation, the PCV would not be introducing anything back into the intake.

It also seems that the higher HP/Boost scenario would include more fuel and more air. Wouldn’t that dilute the concentration of the oil vapor and have an equalizing effect vs any possible drop in Octane?

 

Your data is based on what ppl are saying their cans are catching. That isn't the entire amount of oil their engines, or others are ingesting for an oil change duration. The can only works if the vapor condenses, that is why you mount the cans away from heat. If the gas can't condense, nothing gets captured and continues on its way into the motor. Since you seem to be entirely inept of the google and keep asking us about it, I took the luxury of looking it up and compiling some links:

LSPI- Low Speed Pre-Ignition, its such a problem that oil manufactures build oils specifically to prevent it. This is essentially just the oil on the walls that they are worried about. Don't know how many ounces in 3k that amounts too. But a thin layer on the walls has an entire industry reformulating oils for performance DI applications:
https://www.motor.com/magazine-summa...-pre-ignition/
https://saemobilus.sae.org/content/2016-01-0720

Section 3.1.2: (among others)
https://www.sciencedirect.com/scienc...60128516300764

Almost at the bottom, under "Pre-Ignition Investigation Procedure", there's your math. They essentially say (in hard to understand english) that to fix it, you need an oil that has a flash point and vapor pressure higher than the fuel source. Which isn't the case except for a number of oil I can't even spell
https://patents.justia.com/patent/20180171253

Take note this article was last edited 10/2019. Noted for the "aNy OnE cAn ChAnGe WiKi" crowd. #6 on the list of pre-ignition
https://en.wikipedia.org/wiki/Pre-ignition

While I am no means an expert, these articles/journals essentially support everything I have said: N/A will get by with stock PCV, no issues. That's what its for. Boost needs a venting/rerouting of some type, because OE; the case will get pressurized by the throttle body and passenger valve cover. You're welcome to do/believe/think whatever you'd like, but your opinion isn't going to change an entire industry, and that justia.com journal was seeing pre-ignition at a matter of grams/hr. Now I don't know about you, or anyone reading this, but my non-drug addict self seems to think a gram is a very small amount. A couple grams per hour of consumption? Seems very small. Still seeing pre-ignition? Reason enough for me to try to keep that out of the intake, for a mere $200

 

Where do you think it is going?

Reread my post #27 and believe it this time.

 

For christs sake. Either run a can or not. This is like arguing weather or not to wear a mask during COVID

 

Oh boi, just opened another can of worms lmao

 

Fluid (air or liquid) always flows from high pressure to low pressure. During cruise there is vacuum in the intake so fumes are drawn into the intake. During high load the vacuum disappears from the intake but the positive pressure in the crankcase goes up from cylinder blowby so it still flows from high to low. Have you ever seen a high HP engine on an engine dyno? Ever notice all the smoke and fumes coming out of the valve covers and breathers after a pull? It is not an insignificant amount.

I also dont agree with the oil being purely vapor, I would bet a significant amount is in liquid form or at least condenses quickly inside the intake on the walls.

 

lol, I choose neither... Ha

 

Arthursc2

Thank you for the links. I am familiar with Google and the wide variety of unfiltered content it provides.

I am somewhat familiar with Low Speed Preignition (LSPI). I have done some research and the one thing all of the significant papers have in common is that none assert the actual cause. If you have a paper that asserts reduced octane due to PCV induced contamination; I would enjoy reading it.

This paper seems to speak to the middle ground of academia on the subject. I found it to be more understandable for simpletons like me:

https://pdfs.semanticscholar.org/f8c...45cb911219.pdf


Regarding, “your opinion isn’t going to change an entire industry”. I have expressed no opinion. I have only questioned the causation asserted by marketing materials for catch can manufacturers and retailers, which leads us to believe that PCV introduced contamination causes a decrease in octane, which leads to Boom at the wrong time.

 

Not to argue, but just for reference....1oz of motor oil is 28 grams. A gram is actually a considerable amount

The study you reference was injecting fairly large amounts of oil....directly into the combustion chamber as a liquid. It does provide data, but is not equivalent and cannot be used to draw a correlation to what happens with a mixture of oil and water vapor from the PCV being introduced upstream.




You are correct, on a different note....if you showed up to a “PARTY” with one gram of powdered entertainment....everyone would be disappointed. But, if you alone were consuming, “a couple of grams an hour”, that would be a different story.


Enjoying the discussion.

Still the same question regarding Octane and PCV contamination.

 

I suppose you could buy bulk octane booster for the cost of a high quality catch can and negate any possible octane loss that may or may not be happening due to oil and vapor.