Exhaust Crankcase Evacuation

[2drSE-i]

Steve, this ones for you!


The dilemma was me making fun of Steve for his catch-can setup. I was telling him that it is a way, but not a very effective way, to relieve crankcase pressure.

Stock

In stock Hondas, including our old school beaters, the PCV (Positive Crankcase Ventilation) system is designed to relieve crankcase pressure, which builds and causes poor ring seal, increases blow by, robs power, and puts excessive tension within the crankcase.It does this by pulling a vacuum on the crankcase (See giant black box on the rear of our motor). The way that our vehicles (and many others) do this is by connecting it to the intake manifold. While this is a very eco-friendly model of doing things, its not very effective.


Why? Because you are literally sucking in oil vapors into your intake air. Oil is a very effective octane lower-er. By sucking in oil vapors, you promote detonation, lower power, and a much dirtier engine. Not to worry, our vehicles were designed to handle this (very effectively i might add, these motors last forever).

So whats a good alternative? Heres the lowdown.

I'll do this write up like many others have done on this subject

Power - Poor
Eco-friendliness - Excellent
Reliability - Good

Catch Cans
Yes, catch cans do work, to a certain extent. Rather than pulling vacuum, it creates a pressure differential, which pulls out some of the excess pressure. Not to say catch cans are worthless, but they do not pull a vacuum, help ring seal, or prevent blow-by. They do, however, descrease excess pressure.

Power - Good
Eco-Friendliness - Good (You eventually need to empty the nastiness in the can, bad for the environment lol)
Reliability - Excellent

Electric Vacuum Pump
Hands down the BEST solution. Puts a constant vacuum on your crankcase, very little load, increases power, etc etc etc. Two drawbacks:
1. Venting oil vapors straight to the air. Not a HUGE issue i know.
2. Pricetag. A decent vacuum pump designed for this purpose will cost around $2000. Not an option for 99% of people.

Power - Excellent
Eco-Friendliness - Poor
Reliability - Excellent

Exhaust Evacuation

Here is the queen mother of compromises. It is effective in pulling vacuum, it is RPM dependent so it pulls the most vacuum at WOT, when it is really needed, and it sticks the Oil vapor in the exhaust, which is slightly better for breaking it down (though still pretty bad for the air..)

Heres what you will need.
1. Good baffled catch can (Sealed, not vented)
2. 5/8 High temp oil lines
3. 1/2 of an EVAC kit, summit sells them cheap. http://www.summitracing.com/parts/SUM-120108/
(Its made for a V8. Sell the other half to another 4 Cyl person. You also don't need the Oil cap, as our valve covers already have a bung)


Here is the perfect diagram, with a couple of exceptions.
http://civic-eg.com/pics/diagrams/slash.jpg

1st exception: Its a D-series. Eww (J/K everyone...)
2nd exception: The lines in the catch can need to be closer to the middle, with a drainback to the oilpan in the bottom.
3rd exception: Its running a catalytic converter, and the stock black box. As long as the catch can is very well baffled, no reason to keep the stock black box. Also, for this system to work well at all, you need almost 0 backpressure. The check valves for the evac kit keep exhaust pressure from reversing into the crankcase, but for solid vacuum you cannot have much (if any) backpressure. This means IF you run a muffler, it must be straight through with very little restriction, and no cat at all.

Power - Great
Eco-friendliness - Poor
Reliability - Excellent.

[lostforawhile]

Why are you wanting to remove the stock black box? If you add an oil trap filter between the box and the intake,it's very effective. The black box is an oil separator, it pulls a vacuum under specific conditions through the PCV valve on the intake. it has three connections, one at the oil pan, at outlet to the pcv valve, and one at the back of the box, that is pushed into a grommet on the block, you can't see it unless you remove the box. oil vapors are removed from the crankcase, then the oil is separated out by condensation , and runs back to the pan. This system is so good that I've seen an aftermarket replacement sold for Honda's that cost upwards of 400 dollars. A lot of Late model Honda's without it suffered from a buildup in crankcase pressure, and some oil leaks due to it. The PCV system on these cars is very good at removing blowby gasses and keeping your oil nice and clean, other then an oil trap added, why mess with a good thing? here's a Nismo one for sale that connects between the valve cover and intake, it does the same thing ours does,just not as effective, http://www.priceme.co.nz/Nismo-Oil-Separator/p-883157156.aspx
they sell a system identical to the ones on our cars for aircraft engines, it usually runs around 600-1000 dollars also, if everyone is copying the design, and selling it aftermarket, why mess with a good thing? The pcv system on this car is one of the things that keeps the oil so clean, and helps the engines last so long.

[2drSE-i]

Not that i disagree that the system was well thought out for a production car, It is very ineffective at reducing crankcase pressure. Pulling vacuum from the intake manifold is very limited; it pulls the most vacuum at idle and NO vacuum at all at WOT, when you need it most. Also, the only reason it keeps the oil clean is by pulling oil vapors through the black box, which does have a catalyst inside it to help trap the excess oil, and sucking it straight into your intake air.

You did bring up a good point though. You could easily retain the stock black box. It has everything you need. A drain back for the oil pan, its already attached to the block, hell the PCV valve is nothing but a glorified one way valve. Add the slashcut to the exhaust and change the piping a bit and you've got a really inexpensive, effective ventilation system.

[lostforawhile]

Not that i disagree that the system was well thought out for a production car, It is very ineffective at reducing crankcase pressure. Pulling vacuum from the intake manifold is very limited; it pulls the most vacuum at idle and NO vacuum at all at WOT, when you need it most. Also, the only reason it keeps the oil clean is by pulling oil vapors through the black box, which does have a catalyst inside it to help trap the excess oil, and sucking it straight into your intake air.

You did bring up a good point though. You could easily retain the stock black box. It has everything you need. A drain back for the oil pan, its already attached to the block, hell the PCV valve is nothing but a glorified one way valve. Add the slashcut to the exhaust and change the piping a bit and you've got a really inexpensive, effective ventilation system.when the box isn't effective at specific RPMs the excess pressure goes the other way and out the valve cover breather. there is nothing under it, but a baffle to keep oil from splashing up into the breather tube. also excess pressure can still go through the pcv valve and into the intake, it just overcomes the spring pressure. it can only go one way through the valve, the other reason for the PCV valve is to prevent a manifold backfire from igniting the oil vapors in the oil pan and valve cover area.

[Civic Accord Honda]

i just shoved a big bolt in the hole the pcv valve goes in on my valve cover and stuck a breather filter on the line that runs to the SRI, no more dirty intake manifold, very dirty breather filter and valve cover lol but no more excessive oil usage :D

awesome setup shown here
http://www4.picturepush.com/photo/a/3520167/800/cb7-end-of-may/HPIM0061.jpg

[Civic Accord Honda]

lol but seriously the exhaust setup is definitely the best way, and mine is the worst way but i dont care just so long as im not dumping a qt of oil in it every 200 miles :lol:

[lostforawhile]

lol but seriously the exhaust setup is definitely the best way, and mine is the worst way but i dont care just so long as im not dumping a qt of oil in it every 200 miles :lol:

If you plug your pcv system you are going to use way more oil then you should, it's probably leaking out of every seal on the engine

[gtmst3]

this dosent apply to 3geez does it?:confused:

[2drSE-i]

this dosent apply to 3geez does it?:confused:

Sure does. Not that it happens all of the sudden, but when you go from some vacuum to 0 vacuum and you completely seal it up....just expect to be hunting for oil leaks. If you stick a breather filter on the valve cover, your ok(ish). You didn't seal it, its getting vented, just not evacuated.

[AccordEpicenter]

the exhaust setup will only work correctly if you have almost zero backpressure and it probably wont draw much out just driving around down, so id say for a full race car its the way to go. Catch can and maybe a mechanical or electric vacuum pump is really the best setup if you go all out, except its not cheap. I have breathers on both the vc and the black tank and have had zero issues soo far. Not the best setup but not the worst.

[2drSE-i]

I believe i said that about the backpressure. Mechanical pump would be ideal, if there were a place to put it. I'm gonna try this at any rate and guage how much vacuum is pulled. I've seen somewhere else where someone did this and it was perfect.

[2ndGenGuy]

Catch can inline with the stock PCV system is the best, IMO. I think Lost already described how it works. PCV is designed to work under all engine loads, pulling vacuum where vacuum is best, AND it allows fresh air into the crankcase. You're still going to get some oil vapors passing through the can, but most will get caught in the can. Besides, the small amount of oil vapors that you burn probably aren't even significant enough to show up on a dyno.

[lostforawhile]

the engine mounted vacuum pumps really do work, but expect to pay a lot of money for them, and get very little life. They are dry pumps like on an aircraft instrument vacuum system, and they fail all the time, also when they fail they tend to put a lot of debris into your system. the best option is a wet vacuum pump from an aircraft, but it will be Nealy impossible to get your hands on one, they get rebuilt and reused. I'm also not sure how they would handle the dirty oily air from in the crankcase, they are normally designed to pull filtered air. I changed a lot of stuff on my system, I moved the pickup in the pan, i changed all the fittings to steel, this lets me use braided line, and avoid the impossible to find oil soaked hose at the pan. plus I welded in a piece of heavy wall steel pipe into the box, coolant is circulated through it, from the bypass, when the box is hot, it works best, one of the things that you run into when you plug off the pcv, or use a valve cover breather alone, is you will get a lot of moisture buildup in the oil, this combines with combustion byproducts and you end up with sludge and acids in the oil. the reason the boxes have that foam cover, is to retain heat, this makes sure the moisture can evaporate out of the oil and go up the pcv system. it keeps the moisture from condensing back in the box

[2ndGenGuy]

Well yeah, I should have said aside from the pumps. But those are retarded expensive.

[lostforawhile]

Well yeah, I should have said aside from the pumps. But those are retarded expensive.

if it was possible to get ahold of a wet vaccume pump from an airplane that was past it's service hours, it might be a good experiment, it also may be possible to get a crankcase evacuation pump from a site that sells used racing parts, it will still probabaly be high though.

[gtmst3]

wait so on out cars we have a black box described? i thought out pcv was a line going from the v/c to the intake

[88LXi68]

Adam, I have not read through this yet, but I will today after work at some point. thanks for doing some homework for me. I will add some comments later.

[lostforawhile]

wait so on out cars we have a black box described? i thought out pcv was a line going from the v/c to the intakethats part of it, the pcv valve is installed in the line coming from the oil seperator

[gtmst3]

thats part of it, the pcv valve is installed in the line coming from the oil seperator

im so lost... where is all this located

[AccordEpicenter]

the black box is on the back of the engine block under the intake manifold. The stock pcv system is fine for daily driving, but when you start running boost or going for performance, there are more gasses than the system is designed to handle, and oily combustion by products are not very good for your engine, as it lowers the octane of the incoming fuel and air and promotes detonation, which is very bad.

[Vanilla Sky]

Why not just get an AIR pump and set it up to pull vacuum? How many GM cars have those little smog pumps on them? Now how much would a junkyard one cost?

[88LXi68]

my only concern is that since my car still goes through the emissions sniffer test do you think I would have any issues?

also, my current catch can set up is run off the current black box - does that stay or go?

[AccordEpicenter]

i cant imagine it would show up on a tailpipe only test unless somthing else was way out of whack. The only way anybody would really know, is if they looked at the routing of the lines etc. I kept the black box, i cant imagine it would be a bad thing...

[2drSE-i]

my only concern is that since my car still goes through the emissions sniffer test do you think I would have any issues?

also, my current catch can set up is run off the current black box - does that stay or go?

Black box is fine. Its pretty much like have two catch cans. Sniffer test might be bad though. If you fail the sniffer test all youd have to do is hook the line that goes to the exhaust back to the intake and switch back when your done.

[88LXi68]

I will have to give this a shot then

[guaynabo89]

Steve, this ones for you!


The dilemma was me making fun of Steve for his catch-can setup. I was telling him that it is a way, but not a very effective way, to relieve crankcase pressure.

.



wait wait wait......one second.......


Steve showed you his catch can!


damn it, he wouldnt even open the hood for me let alone show me anything.:burn:

[2drSE-i]

wait wait wait......one second.......


Steve showed you his catch can!


damn it, he wouldnt even open the hood for me let alone show me anything.:burn:

Haha, your just jealous because i didn't make fun of your catch can!

[guaynabo89]

lol


you couldnt find my catch can. :naughty:

[Civic Accord Honda]

If you plug your pcv system you are going to use way more oil then you should, it's probably leaking out of every seal on the engine

its not completely plugged the valve cover has a breather on it which sprays my valve cover and sprak plug wires in oil :lol: but its only temporary until i can make myself a new catch can and hook it up that way, and it is burning less oil this way
i have around 273k on my engine so there is a lot of blow by
less blow by now that i adjusted the valves tho which is weird

[lostforawhile]

its not completely plugged the valve cover has a breather on it which sprays my valve cover and sprak plug wires in oil :lol: but its only temporary until i can make myself a new catch can and hook it up that way, and it is burning less oil this way
i have around 273k on my engine so there is a lot of blow by
less blow by now that i adjusted the valves tho which is weird

without the circulation through the crankcase, your oil is going to load up with sludge and acids formed from the sludge combining with water. the circulation is needed to remove water vapor, the valve cover breather isn't going to let the water escape. you aren't old enough to remember engines with road draft tubes instead of PCV systems, every one of those engines would be coated with sludge inside. The pcv is much more then emissions, it stops sludge formation inside of the engine

[Civic Accord Honda]

yeah which is why i plan to hook it back up with a catch can (one of them water sepraters or w/e there called from home depot and HF that go on air compressors) but for now i couldn't afford to keep dumping oil in her lol, ill get it fixed next month

[AccordB20A]

i got tired of my car severly smoking, when i took the intake off there was like puddles of oil in the runners. i stopped this and half of the smoking too by plugging the vacuum line from the intake and taking the pipe off that black box thing so now it just vents out to the air, i dont know how effective this is but at least now after 7000rpm accelerating heavily i can still look and see whats behind me in the rear view mirror, rather than a blue cloud of smoke screen

[Xaisk]

Interesting. So what your saying is that putting one of the breathers on the crankcase vent isnt the most promising way to do it? and that a catch can is what I need?

What exactly is a catch can and what does it do?

Also how much would one be and how hard would it be to set it up?

[2drSE-i]

Interesting. So what your saying is that putting one of the breathers on the crankcase vent isnt the most promising way to do it? and that a catch can is what I need?

What exactly is a catch can and what does it do?

Also how much would one be and how hard would it be to set it up?

A catch can is just a ventilated can that is tied into your crankcase and/or your valve cover, to catch excess oil vapors and/or blowby. I'm not sure where you have your breather filter connected, i assume on the side of the valve cover? if so, no sweat. As long as you didnt seal it your ok. Chances are, no oil will ever come out of there.

[Xaisk]

A catch can is just a ventilated can that is tied into your crankcase and/or your valve cover, to catch excess oil vapors and/or blowby. I'm not sure where you have your breather filter connected, i assume on the side of the valve cover? if so, no sweat. As long as you didnt seal it your ok. Chances are, no oil will ever come out of there.

I didnt seal mine and havent had any issues yet.

But I live in Mississippi and lost said that if you dont use a catch can, itll be more susceptible to water turning the oil more acidic and lowing your detonation power. Mississippi is RIDICULOUSLY humid so thats a very probable issue.

I would be wise to get the can.
Ill probally make one using that guide posted further down the page.

When making one Id pretty much route it from the crankcase to the can then to the breather on the valve cover right? then just put my little filter onto the can?

[Accordtheory]

Stock

In stock Hondas, including our old school beaters, the PCV (Positive Crankcase Ventilation) system is designed to relieve crankcase pressure, which builds and causes poor ring seal, increases blow by, robs power, and puts excessive tension within the crankcase.It does this by pulling a vacuum on the crankcase (See giant black box on the rear of our motor). The way that our vehicles (and many others) do this is by connecting it to the intake manifold. While this is a very eco-friendly model of doing things, its not very effective.


Why? Because you are literally sucking in oil vapors into your intake air. Oil is a very effective octane lower-er. By sucking in oil vapors, you promote detonation, lower power, and a much dirtier engine. Not to worry, our vehicles were designed to handle this (very effectively i might add, these motors last forever).

So whats a good alternative? Heres the lowdown.

I'll do this write up like many others have done on this subject

Power - Poor
Eco-friendliness - Excellent
Reliability - Good


I just want to clarify a few things. First, the factory pcv system is not designed to "pull a vacuum" on the crankcase, it is designed to dilute the blow by in the crankcase with fresh air under part throttle (like 95% of normal) driving. Huge difference there. The difference is literally thousands of miles in the oil change interval. You say "a much dirtier engine", well I sure would rather have my intake manifold dirty than my oil.

2drSE-i, what are you trying to do? a slash cut tube in the exhaust with a 1 way valve is a horrible pcv system for a street car. You won't have enough vacuum to make it work most of the time, and the blow by will not be diluted, and will end up exiting through the breather.

When you say you need your pcv system most during full throttle, well, maybe, but since the car only spends a tiny percentage of its time under full throttle, it doesn't have a huge overall effect on oil life.

I suppose you could modify the pcv system on a car to extend the oil change intervals, I'd probably do it by starting with a larger, higher flowing pcv valve, and then do whatever else was needed to support that higher flow rate, like maybe a bigger breather box too.

[Accordtheory]

Not \Pulling vacuum from the intake manifold is very limited; it pulls the most vacuum at idle and NO vacuum at all at WOT, \

the PCV valve is nothing but a glorified one way valve

It is actually a little more complex than that. It is designed to have a non linear flow rate vs vacuum. In other words, at part throttle cruise, you have less vacuum than at idle, but still need a lot of flow. At idle, you have maximum vacuum (oem cam anyway) but don't need a lot of airflow through the valve. So they designed it to where that higher vacuum actually pulls the valve more shut. Of course, at full throttle the valve is closed, not that it would be doing anything anyway, except the possible failure mode of bleeding boost into the crankcase on a turbo car. I always make it a point to tell people with forced induction to check their pcv valves and make sure they actually seal. The oem metal ones are really good quality, unlike the cheap auto parts store crap.

[lostforawhile]

let me explain this one more time, air enters the crankcase at the breather on the valve cover, thats why it's hooked to the air cleaner, so it doesn't pull dirty air through the entire engine, the air is circulated and pulled down through the engine by vaccume caused by the pcv valve, while it's doing this, it picks up water vapor and combustion byproducts, if it wasn't working, these would end up in your oil, and form sludge and acds. the vapors are picked up at the back of the oil pan, and travel through the hose at the back of the pan. they enter the oil seperator box, (the black box at the back of the engine) all this box is, is an empty metal box, with a baffle in it. they travel towards the top of the box, as they do this, residual oil condenses out, and travels through a tube pushed into the back of the block, yes it has three openings, you can't see this one, unless you remove the box. This oil travels back to the pan through the oil return passage from the head. Thevapors are picked up at the top of the box and pulled through the pcv valve,to be burned in the engine. The pcv on this car is actually excellent compared to a lot of other Hondas, The only thing you might want to do on a non turbo car, is add another seperator before the intake manifold. A lot of people use oil/water seperators from Home depot or Lowes. Don't remove the system, or try to modify the rest of it, it's fine the way it is. Check your hoses for cracks or leaks and replace as needed.