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Wow!!!

You are an open minded thinker Mark.

Most can't comprehend an Engine with no PCV and most do need them.

Our Engines do not, but need they the ability to exhale crankcase vapors freely.

As you're running a pre common block the fuel pump hole is a nice vent spot.

Some run TBI valve covers as they have 2 nipples and that's usually sufficient.

NO VACUUM is required or beneficial, it can only be harmful!!

Thanks
Randy
 

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Randy. My thoughts exactly on the vacuum, at least when the motor is fairly fresh. Have you seen people's modifications to the block off plate? Do you have to use a valve of some sort, or just a filter?
 

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1989 Dodge Shadow 2.5 non turbo 3 speed automatic
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Some run TBI valve covers as they have 2 nipples and that's usually sufficient.
I have a 2.5 TBI and your comment just made me think do the dual ports actually do anything. I’m thinking the PCV one would just suck air from the other one that connects to the air box before the TBI. Refer to pic.
274501
 

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Harmonica, that is exactly what a PCV system is supposed to do.

One nipple draws contaminated vapors from within the crankcase.

The other allows fresh, filtered air to enter the crankcase.

Older V8 Engines illustrate this nicely.

Most every Engine NEEDS a PCV system

This includes our TBI Engines.

Our 8V Turbo Engines DO NOT.

Thanks
Randy

274502
 

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One nipple draws contaminated vapors from within the crankcase.

The other allows fresh, filtered air to enter the crankcase.
To me it seems like it only ventilates the head. And I don’t believe the vent hole is filtered as it sucks from before the engine’s air filter.

Why don’t the turbo engines need a pcv system?
 

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Some run a pipe or hose from the block off plate.

It must be elevated to prevent oil splash from blowing out.

Blowby is like the ocean, it can not be held back, only directed.

The larger the opening the better especially concerning catch cans.

Any restriction can act like a venturi and suck oil out along with vapors.

Shadow has one of the best crankcase ventilation systems I've seen.

I call it his "intercooled ventilation system" because it looks so cool.

One can almost see it on the beginning of this vid.

Someone might have a picture.

Thanks
Randy.




Randy. My thoughts exactly on the vacuum, at least when the motor is fairly fresh. Have you seen people's modifications to the block off plate? Do you have to use a valve of some sort, or just a filter?
 

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The crank case is considered any internal part of the Engine that's oil related.

This includes the block, oil pan, valve covers and passage ways etc.

Blowby blows past the piston rings and creates crank case pressure.

It doesn't care how it gets out but it will get out, bank on it.

Through the valve cover, seals, gaskets or dipstick tube.

Obviously, the cooling system isn't part of the crank case.

I didn't design the TBI system, I only observe it.

Why don't our 8 V Turbo Engines need a PCV??

Think man, THINK!!!

Thanks
Randy

To me it seems like it only ventilates the head. And I don’t believe the vent hole is filtered as it sucks from before the engine’s air filter.

Why don’t the turbo engines need a pcv system?
 

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Discussion Starter · #168 ·
Nice! I like to see this thread getting some traction with quality banter!

So lets jump into the PCV conversation.

You are so right that many of the more seasoned TD'ers live by "the factory pcv system is at its best and youll only muck it up if u mess with it." This was the basic response i got when trying to figure our why a new turbo was smoking so badly (all the while the valve cover was taped up and no way for the crankcase to vent).

Back then, my "improvement" to the factory pcv system was to run vacuum source to the valve cover with a catch can in between. My vacuum sources were either the intake manifold or the turbo inlet. I used two gm 3/8" check valves to keep the flow directions correct. This way boost never flows from the manifold nor manifold ever draw from the turbo inlet. It functioned well, albeit she deposited a whole lot of oil in the catch can. But it was still flawed.

PCV Sytem:
1)Vents positive crankcase pressure which only exists from blow by as well as expansion of the crankcase atmosphere from heat.

2)Reduces emissions by cycling the blow by back through the intake to be burned (rather than dropped onto the ground or vented to atmosphere).

3)Saves seals where excess crankcase pressure would otherwise harm them.

4)Reduces contamination of the oil in the sump again by scavenging the blow by out of the crankcase.


The real downfall of our system is the lack of fresh air flow, as we mentioned before. The way our system is setup, the crankcase atmosphere is 100% nasty blowby that only gets flushed out as new blow by enters the crankcase. I like your thought about the fuel pump block off plate, even the dipstick tube is more than large enough to provide a vent. The pickle of the whole thing is that you need to think that you will be creating and induction circuit that the ecu will need to account for. This is effectively an air source that is parallel to the throttle body/ais motor. We have now stumbled on why pcvs, the valves themselves, are designed the way they are. They are made so that as differential pressure is maximized, flow is minimized. Read as the flow little at idle but most at wide open throttle. Engineering!

Our stock system still sucks and there isnt an easy fix...
 

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Discussion Starter · #169 ·
Continued.

Why do you believe that crankcase vacuum is a bad thing?

There is no doubt that excess vacuum can harm seals. But thats the only thing i can think of.

The positives i can think of:
Helps oil flow back to sump (turbo and head).
Reduces the density of the crankcase atmosphere so saves windage losses.
Helps mitigate blowby.
Promotes ring seal (this one is one that ive heard for decades but have never rationalized why nor has it been explained to me by someone knowledgeable)

Negative crankcase pressure is one of the effects of a dry sump oil system that many regard as a good thing.

I am all ears! Lets think up the best dang PCV/vacuum/vent system that we can come up with collectively.

Thanks guys,
Mark
 

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I don't know if anybody is familiar with the "road draft" systems of cars from the 60s and back. They use a venturi effect with a pipe positioned down into the airflow under the car to create a vacuum that draws air through a breather on the valve cover. Besides having to change oil more often, I don't see the draw back of putting breathers in multiple locations and calling it a day. I would love to see Rob's setup on the Charger. Also, I don't want to fill up and derail SRT's really good build thread with extraneous discussion.😬
 

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1989 Dodge Shadow 2.5 non turbo 3 speed automatic
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Could you add a firing to the air box after the filter (so you don’t suck crap into the engine) and run a line with a one way valve down to the oil pan and add a fitting there. Then add a second fitting to the oil pan and have that run up to the valve cover with another custom fitting then use the factory nub on the valve cover to make the vacuum and burn the bad gasses.
 

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Remember, I'm talking about our 8V Turbo Engines today, nothing else.

Crank case vapors only contaminate the Engine air intake with no benefit.

They serve no good purpose and contaminated air reduces fuel octane.

Detonation is our enemy and we need to protect against it.

Any vacuum from any where risks ingesting contaminates.

No vacuum means no oil in the intake, intercooler etc.

That said, why don't our 8V Turbo Engines need a PCV??

Most other Engines do for a couple of reasons.

I wouldn't recommend no PCV spuriously.

Thanks
Randy
 

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I've been racking my brain all evening Randy!:ROFLMAO: The suspense is killing me. So are you saying that the 16 valve 2.2 needs a PCV?🤔
 

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Probably but I don't have any experience with them.

It's the old 8V Turbo Engines I know a bit about.

Excellent question though, it shows you're thinking!!

As its Marks thread I'm waiting for his input.

Thanks
Randy
 

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Discussion Starter · #176 ·
Oh gotcha. I missed the name of the game.

Now time to think...

To not need PCV suggests that there isnt a positive crankcase pressure problem...

Do 8v turbos not have blowby problems?? No. No thats not it.

Do they vent in a way atypical to other vehicles?? Well that would explain some of the oil leakings... Oh is that it? Valve cover gaskets design to "seep" positive crankcase pressure??

Thats probably not it...

Hhhrrrrmmm...

I think you got me. I cant think of a single reason why our 8v Turbos are the exception to the internal combustion world.

Whatcha got Randy? We are dying to hear the good word.

Excitedly,
~Mark
 

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Oh gotcha. I missed the name of the game.

Now time to think...

To not need PCV suggests that there isnt a positive crankcase pressure problem...

Do 8v turbos not have blowby problems?? No. No thats not it. CORRECT !!!

Do they vent in a way atypical to other vehicles?? Well that would explain some of the oil leakings... Oh is that it? Valve cover gaskets design to "seep" positive crankcase pressure??

Thats probably not it... CORRECT !!!

Hhhrrrrmmm...

I think you got me. I cant think of a single reason why our 8v Turbos are the exception to the internal combustion world.

Whatcha got Randy? We are dying to hear the good word.

Excitedly,
~Mark
Please keep thinking!!!

It tastes better when one gets it !!!
 

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They don’t need a PCV because the head gasket all ways blows and lets the presure into the cooling system.
(Just kidding of course)

The only thing i can think of (not having a turboed one 🙁. Sad N/A 2.5 noises) is maybe the oil fill cap has a vent like a lawn mower gas tank. I’m guessing that because the fill cap is all ways looks larger on turbo cars.
 

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Think about what a PCV system removes from the Engine crankcase.

Thanks
Randy
 

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Discussion Starter · #180 ·
Weve explored all avenues that im aware of.

PCV system removes hydrocarbon rich blowby from the crankcase. Consequently oil vapor from the crankcase atmosphere as well. I think that is 100% of what come out.

The hydrocarbons are bad for the environments, hence the manifold connection to burn them up.
The oil vapor is bad for our combustion cycles because it drops octane rating.
Its a catch 22.

Thats why it seems like the best solution is a functioning system to burn hydrocarbons, with the introduction of catch can to reduce oil ingestion, with increased crankcase vacuum to promote ring seal to reduce blow by in the first place.

What are your thoughts Randy?

~Mark
 
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