Crankcase under boost conditions

[Major Kong]

Question

I'm wondering if anyone has any input regarding crankcase pressures under boost conditions
The goal of my inquiry is to determine if it is beneficial to add a ball check breather
Finding intel online is not readily available or maybe I'm looking in the wrong spots

Vid describes crankcase pressures under full throttle boost conditions
PCV system vacuum drops while blowby pressure increases
Crankcase pressure increase
Detrimental to seals

Ball check breather seems to make sense
Wondering if the Dragon 1.5 has a function to address this pressure issue already

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[Major Kong]

The aha moment

The ball check waste dumps to atmosphere
EPA says Kong bad
Now pondering
Ponders hard

How does Ford address crankcase pressure when vacuum drops
How might this affect seals
As the video shows a reverse flow within the fresh air delivery might occur
Not sure if it was designed to handle the load

 

[Mark S.]

How does Ford address crankcase pressure when vacuum drops

Might be an issue for track cars whose engines spent the majority of their lives in heavy boost.

How might this affect seals

Haven't heard about widespread issues, have you?

Not sure if it was designed to handle the load

The wife's 2014 Escape (2.0L) went 130K with no leaks or other excess crankcase pressure related failures. That's anecdotal, but coupled with a dearth of widespread reports about same I'm confident in the design.

 

[Major Kong]

Might be an issue for track cars whose engines spent the majority of their lives in heavy boost.


Haven't heard about widespread issues, have you?


The wife's 2014 Escape (2.0L) went 130K with no leaks or other excess crankcase pressure related failures. That's anecdotal, but coupled with a dearth of widespread reports about same I'm confident in the design.

Heavy Boost - yep, definitely not me. Light on the pedal soaking in the scenery. The vid kinda pointed out several times mentioning the boosted stock engine and if there was a need.
It might be interesting though just to see what kind of case pressures are generated under those circumstances. As far as gaskets and seals are concerned this would have been baked into the cake during design. I did contact the maker of the relief check and did present a couple questions.
If I were really ambitious I might be inclined to see if there is a gauge which reads neg / pos atmospheric and slip that in the PCV line to get a better understanding.

Heard about seals - No, if fact it's pretty difficult just to find info on the fresh air intake into the case. The subject has very little discussion to form an opinion. So, I was pleased to see your response. About the 2014 Escape, was it a boosted engine?

 

[Meanderthal]

One thing to consider is that lots of vehicles have 2L turbo engines from a long list of brands. This crankcase pressure issue is a “nothing burger”. I’ve been driving a VW Golf R and regularly pushing boost levels of 20 psi+ for the last 10 years and have never had this issue nor heard about it in the VWVortex forum (read daily).

 

[Major Kong]

One thing to consider is that lots of vehicles have 2L turbo engines from a long list of brands. This crankcase pressure issue is a “nothing burger”. I’ve been driving a VW Golf R and regularly pushing boost levels of 20 psi+ for the last 10 years and have never had this issue nor heard about it in the VWVortex forum (read daily).

Input appreciated
Still not ready to abandon the idea. A release to balance or return to neg pressure as optimal condition would seem best.

"have never heard this issue" likewise

Just starting to follow up on this pursuit
Had the opportunity to ask my mechanic today concerning the issue
"I'll get back to you on that one"
It would seem if it were truly an issue mechanics would be the first line info
But stubborn to a fault I'll go on til the bloody end
Whether it bears fruit or not
Retired guys
It's a way of life

 

[Mark S.]

Retired guys
It's a way of life

LOL! What else you got to do? BTW, wife’s 2.0L was boosted; same engine as Badlands.

Yeah, here I am sitting on this bar stool,
Talking like a damn fool
Got the twelve o'clock news blues
And I've given up hope for the afternoon soaps
And a bottle of cold brew
Is it any wonder I'm not crazy
Is it any wonder I'm sane at all
Well I'm so tired of losing
I've got nothing to do and all day to do it
Well I'd go out cruising, but I've no place
To go and all night to get there
Is it any wonder I'm not a criminal
Is it any wonder I'm not in jail
Is it any wonder I've got too much time on my hands
It's ticking away with my sanity
I've got too much time on my hands
It's hard to believe such a calamity
I've got too much time on my hands
And it's ticking away, ticking away from me

 

[Major Kong]

and regularly pushing boost levels of 20 psi+

Well that gives me something to work with.
If the engines case ventilation is similar in configuration the 20+ psi being on the downstream side of a PCV check valve it could be assumed

• the case pressure did not exceed the boost pressure of 20+ and was below that reading
• the case pressure exceeded your boost pressure and the 20+ was a combination of both inputs the case pressure being the greater of the two
• shit - back to square one

 

[Major Kong]

Threads like this one are interesting. I'm in a different world with new cars. Most of what I've driven for decades are old sports cars, old trucks and 4-wheelers for hunting. I need to learn a lot.

Confirmed
It's only of recent time did I finally start driving something made in the same century

 

[Meanderthal]

Well that gives me something to work with.
If the engines case ventilation is similar in configuration the 20+ psi being on the downstream side of a PCV check valve it could be assumed

• the case pressure did not exceed the boost pressure of 20+ and was below that reading
• the case pressure exceeded your boost pressure and the 20+ was a combination of both inputs the case pressure being the greater of the two
• shit - back to square one

The crankcase will never hold any pressure, within reason. Sorry I’m an engineer, so absolutes are hard for me to say. The PCV system will not allow any pressure to be held in the crankcase. Once the turbo spools, the only things under pressure are from the turbo to the back of the intake valves.

If this was an issue, it would also happen in non-turbo engines. During the compression and combustion strokes there is some small level of “blow by” the rings. That would lead to extra air in the crankcase which would eventually build up a pressure, if not for the PCV system. The PCV system bleeds any excess back into the intake tract.

Just for anyone reading this that doesn’t know: PCV = Positive Crankcase Ventilation

 

[Major Kong]

The crankcase will never hold any pressure, within reason. Sorry I’m an engineer, so absolutes are hard for me to say. The PCV system will not allow any pressure to be held in the crankcase. Once the turbo spools, the only things under pressure are from the turbo to the back of the intake valves.

If this was an issue, it would also happen in non-turbo engines. During the compression and combustion strokes there is some small level of “blow by” the rings. That would lead to extra air in the crankcase which would eventually build up a pressure, if not for the PCV system. The PCV system bleeds any excess back into the intake tract.

Just for anyone reading this that doesn’t know: PCV = Positive Crankcase Ventilation

"The crankcase will never hold any pressure, within reason."
Major's anal response - *within reason* lots of wiggle room with that caveat.
I think you would agree though there is a negative pressure under most situations. But that really isn't the issue here. The discussion is the loading under boost conditions.
The ideal scenario would be the negative vacuum to a continual clearing of unwanted case vapors.
"The PCV system bleeds any excess back into the intake tract."
If I'm correct yes this is the emissions function of the PCV system. However when the boost pressure exceeds that of the case pressure the PCV check closes when a reduced vacuum exists. The normal flow direction of the case vapor to the intake manifold would cease. A reverse flow potentially would occur in the fresh air supply line. So it is not a closed system and there is a means for release of pressure by this reversal. >edited< But that in turn is fed to the intake downstream of the MAF only to meet up again with the boost pressures?
Returning to my original question would a relief check be useful?
I still see some value to maintaining a balanced to negative pressure.
Crankcase pressure builds may not and most likely do not impact the seal/gasket integrity otherwise there would have been a flurry of info on the web.

 

[Meanderthal]

Returning to my original question would a relief check be useful?

I have to believe that with the thousands of hours of testing and design on small displacement turbo engines, if a relief check was beneficial, it would have been implemented. Especially considering how cheap it would be to implement.

 

[Major Kong]

I have to believe that with the thousands of hours of testing and design on small displacement turbo engines, if a relief check was beneficial, it would have been implemented. Especially considering how cheap it would be to implement.

I would agree on that but they cannot implement this without breaking emissions regulation. Going straight to atmosphere ain't gonna wash.
My best approach to that might be to dump it into a canister such as the fuel tank vapor might be handled.
Anyways it's a pleasure to have discourse with an engineer such as yourself.
They always seem eager to take on a challenge with reason.

But in the end I think it may be a difficult position to argue against having a means to seek minimal case pressure builds. Why not look for a response to the issue?
Problem is I don't think there is a affordable one so the easiest way out is to ignore it.

 

[Mark S.]

Problem is I don't think there is a affordable one so the easiest way out is to ignore it.

Or you determine via testing that brief periods of high crankcase pressure (experienced only those times under high power demand) do not affect the seals. Or you determine via testing it does and change the specification to a more robust seal. Or...

There are always alternatives.

 

[Major Kong]

Or you d[/COLOR]etermine via testing that brief periods of high crankcase pressure (experienced only those times under high power demand) do not affect the seals. Or you determine via testing it does and change the specification to a more robust seal. Or...

There are always alternatives.

Correct, but I believe the issue response is to take a pass and ignore.


Brief periods
Then again it's at these periods where the highest volume of contaminants are entering into the case and the PCV ball check is closed. Ventilation at this time ceases and the only release is the flow reversal. Seems though, when you would want this vented the most would be at this point in time.
Unfortunately you're stuck in a room with a farting dog and someone shuts the windows. (offered up as a mental visualization)

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