Dm914

Hey im a newbie to all this but I recently bought a EK Hatch Off my buddy. It has a B16A with a Type R manifold, Headers, Aem Fuel Rail, and a CAI. I noticed a tiny breather looks like an intake on my valve cover. He said when he bought the valve cover it came with it already attached. I know a hose from the valve cover should run to the intake but this breather is in place of that hose. The entry for the hose on the intake is open. I know its for ventialtion purposes but i was reading that on engines that rev to high RPMs its best to keep it on instead of a hose. Just want to Know if its true or not. I checked other similar threads but its really just a bunch of people going back and forth saying yes and no towards its functionality. Should I keep it on and plug that entry on the intake? or just run a hose?

Former User

Run the breather hose on the valve cover to the intake, or add a filter. You don't want dirt and debris getting sucked into the head and crankcase. Also make sure the PCV hose and valve are connected to the IM and oil breather chamber.

TomCat39

From what I understand, it's best to return to stock setup and run the hose from the intake to the valve cover. This pressurizes the PCV system which in turn reduces blow-by to some degree. If you wish to reduce oil going into your intake for the high rpm it's best to add a quality oil catch can in between the breather box and the entry point into the intake. Your choice if it is before or after the PCV valve itself.

Also, having an open hole in the intake tube itself is foolish as it allows dust and dirt to be sucked straight into the engine. Sort of negates the purpose of an air filter if you ask me.

Former User

The PCV system actually depressurizes the crankcase using vacuum from the IM.

TomCat39

Hmmm, now I have to find that thread that discussed this. Need to see if I misread, it was incorrect or if it just contradicts that.

Found it, came from Team Integra quoted in this post:

https://honda-tech.com/acura-integra.../#post44350017

Former User

Some of the terminology used in the quoted post is ambiguous. However, the concept that the breather provides positive air pressure is just plain wrong. Instead, gases in the crankcase are sucked out by vacuum created in the IM.

TomCat39

That doesn't make sense. Why would the gas go from the crank case, up the oil return holes through the valve cover into the intake tube to enter the throttle body. That would also pull pressure from the breather box, pcv valve and fight the draw from the plenum of the intake manifold. It's the tube from the intake tube that OP is missing as well as a breather filter is added to the valve cover portion where that tube is removed.

The tube from the intake tube to the valve cover blows air to pressurize the crank case and aid pushing gases into the breather box, through the pcv valve into the intake manifold plenum as well as provide some positive pressure to the back side of the piston rings reducing some blow by.

This one here:


Notice the breather filter and the empty/plugged hole in the intake tube where the tube should be to the breather filter spot.

Former User

Where did I say this^?

You and the quote at the link are saying pressure from the intake is pushing air out of the crankcase into the IM. This is wrong. Instead, it's vacuum from the IM pulling gases from the crankcase, with the breather hose simply allowing for continuous air flow out of the crankcase, without creation of a vacuum.

Nope, this^ concept is the same as what was quoted at the link. It's wrong.

TomCat39

I don't believe the tube from the intake is negative pressure. The amount of air rushing towards that tube would prevent "continuous flow" from the crank case when the IM isn't producing sufficient vacuum. The pressures would be fighting each other, the pressure from the intake vs the blow by from the crank case.

The air rushing towards the tube to the valve cover is going to create a positive pressure. Which in turn will create a positive pressure in the crank case.

Removing the hose from the intake and the valve cover removes that positive pressure.

I am not saying the IM doesn't create a vacuum, I'm just saying there is a positive pressure in addition to the vacuum of the IM when the system is set up as Honda designed with the tube in place.

If you take a look at the full post on team integra, you will see even the diagram in the helms manual shows the tube from the intake is a positive pressure system pushing fresh air into the valve cover thus pushing fresh air to the crank case:

Team Integra Forums - Team Integra - View Single Post - Valve Cover Breather Debate



From the 92-95 FSM

Former User

This is correct only at WOT. At WOT, some crankcase gas may in fact be pulled from the breather into the intake by the Venturi effect.

Under no condition will this^ be true. There will never be positive pressure from the intake to the breather hose. The reason is because the most air rushes past the breather into the TB. This will actually pull some air from the breather into the intake due to the Venturi effect. It's Physics 101.

Nope. That's wrong.

Nope. I know this idea feels right for you, but it's wrong. The only positive pressure would be from blow by, not the breather.

TomCat39

Not even a matter of feels right, is displayed in the helms manual as the flow of air as can be seen on page 11-140

Former User

You don't realize that we both agree on the direction of air flow. What we disagree about is what is the underlying cause of the direction of flow.

You say that the air flow direction is determined by air pressure pushing from the breather into the crankcase. This is incorrect.

I am telling that air flow in the system is instead determined by vacuum from the IM pulling air/gases from the crankcase and that the breather hose has a passive role in the process. There's no push. There's only pull.

tony_2018

intake manifold sucks through the valve cover. Those filters don't do jack but make your car look pretty. Not sure but I believe there is another diagram for the b-series that shows something similar. Gotta look it up after walking the dog.

edit: my bad, reverse what i said. There's also a discussion on H-T already on this but its an old one

https://honda-tech.com/forced-induct...tended-697498/

TomCat39

I had to go to bed to get up this morning but I'm glad I did. Just as I was starting to doze off everything clicked.

I know you are painfully aware of my not understanding what you meant by continuous air flow as well as a couple of other things.

Just as my mind was about to wander into never never land, the light bulb goes off. What I see is the IM is pretty much constantly drawing air but basically at different degrees. Without a breather tube it would likely cause a significant negative pressure in the crank case as the blow by doesn't likely get to the same levels as the draw from the IM. The breather tube allows for continuous fresh air from the intake tube to keep that negative pressure down to as close to zero as possible.

Like you said, on both counts, the flow is correct in the diagram and the error is in the interpretation that the breather tube is a positive pressure. I understand now. It IS a negative system, the breather tube is to prevent the pressure from becoming overly negative as the ideal would be a zero pressure condition but just is not possible in the real world.

So if anything the only real slight negative to having a breather filter instead of the breather tube is the filter might pose a slight restriction to the fresh air flow from the negative pressure pull of the IM through the breather box etc thus causing a slight decrease in efficiency of the vacuum.

Thanks for clarifying that as we can see it's very easy to misinterpret the air flow diagram and get the wrong conclusion of the breather tube as can be seen with the post I quoted and the threads I referenced.

Former User

You got it TomCat.

Dm914

So I should just run that hose from the valve cover to the intake? Because like i said i bought this from a reputable shop and it came with that breather already installed. But it was a new guy there that made the transaction. He said either the filter or hose it does the same job. But i figure the filter would have more restriction in air flow. I just wanna know if im causing any damage to my engine because motor swap money isnt pocket change for me at least. If it does the same job as the hose should i just plug that hole in the intake?

Former User

Connect hose to intake as intended by Honda.

TomCat39

I must say, I don't know of ANY introductory physics classes (101) that get into the complexity of air circulation.

All 101 classes I've ever seen introduce physics in a vacuum only. :p

Former User

First-year college Physics 101 principles are generally taught in two consecutive semester courses, such as Physics I and Physics II. The Venturi effect would be covered in the second half. Any advanced high school student would also be exposed to the principle.

TomCat39

I stand corrected.