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Discussion Starter · #1 ·
hi im woundering, i put an after market cold air intake on my d16y7 and im woundering if i should hook the hose that come from the valve cover to the cold air intake cause it doesnt have a hole for it or should i just go to auto zone and get a small filter and put it on the little neck on the valve cover thank you for helping me guys!!
 

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EG8
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I use a little one way valve there.
Which way do you have this check valve?

I actually looked into this and apparently its not really good to do that..

Apparently flow is into the crank case at lower loads, and then at higher loads it flows out of the crank case into the intake.

But it wasn't my personal tests so I can not vouch, and it was done on Honda-Tech lol... But I'm not sure what advantage the tester would gain by lying either? So take it or leave it.

Simple thing is to just keep the line or do a filter.
 

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Discussion Starter · #10 ·
ok thats good info and no i work at AZ meaning auto zone lol sorry i should have been more specific lol and i might just do a filter so i dont have to tap a hole for the line or what would you do?
 

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EG8
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It has a lot to do with the PCV system and having very little vacuum in the upper load levels.

The breather hose is best if you do not intend to drive hard and usually part throttle and under 3k or so.

The filter is better when closer to WOT and higher RPM due to the pressure increase and blow by.

I personally have not figured out a simple solution to having a closed system without having a lot of hoses and check valves everywhere and crap lol.

I might have an idea, but my new car is still in the works so no testing yet lol.
 

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EG8
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Filter, colder air, unless you have to deal with california smog restrictions.
Yea the hose is mostly for emission to burn off the oil that will escape while venting the pressure; which mostly comes from higher loads..

That's why most just use a filter so the crap doesn't go into the motor..

I'm just complicated lol!
 

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Which way do you have this check valve?

I actually looked into this and apparently its not really good to do that..

Apparently flow is into the crank case at lower loads, and then at higher loads it flows out of the crank case into the intake.

But it wasn't my personal tests so I can not vouch, and it was done on Honda-Tech lol... But I'm not sure what advantage the tester would gain by lying either? So take it or leave it.

Simple thing is to just keep the line or do a filter.
thanks to my intake pipe I cant use a line. Its funny I thought that pipe was only meant to vent out and hence I fixed the valve in the same direction. ill find a filter and fix it. Thanks.
 

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EG8
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thanks to my intake pipe I cant use a line. Its funny I thought that pipe was only meant to vent out and hence I fixed the valve in the same direction. ill find a filter and fix it. Thanks.
Lol, glad I could shed some light on the subject... but really I wish I had a solid solution to this. Soon I should, hopefully.
 

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I really prefer an oil catch can over the opened breather or hooking back up to the intake tube directly.....this keeps oil off the outside of the engine, keeps pulpit of the intake tube, and keeps a small vacuum on the valve cover.
 

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Personally, I would rout it back into the intake. That's how factory has it, so that's how I have it. And will continue to have it until I go turbo.
The main reason for not doing this is that oil mist can be drawn from the crankcase into the intake, and then it will coat the throttle body plate and the inside of the intake with oil, which over time will build up and can cause problems. A second minor reason is that it introduces heat into the intake charge (not much).

The reason for routing it into the intake is to allow unburned combustion gasses that blow by the piston rings to flow back through the combustion chamber for a second chance at being burned...this is environmentally more friendly than running it open.

If you go with just the breather filter attached directly to the valve cover, be aware that the oily mist will still be flowing out that port and will coat the inside of the filter, eventually clogging it. You want to clean that filter from time to time to prevent this.

The final option would be to route the port to a catch can which would allow the oil to collect (and the gasses to cool a little) and then let it breathe via a crankcase filter or even routing it into the intake again (should be much less oil mist in the gasses that way).

None of these approaches will result in your car bursting into flames or producing significantly less power.
 

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With proper slash tube in the intake tubing, you won't get the oil mist into the intake manifold if PCV is working right.

If you do, motor needs a rebuild anyways.

I'll NEVER have a filter on the valve cover!
 
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