mattsnooz

Getting ready to run Vacuum lines in my setup but had a few questions.
I know how I'm suppose to run the vacuum lines I believe, but I want to understand how the vacuum/boost affects the systems attached to the intake manifold.

When your intake manifold sees boost, do the other systems operating off vacuum operate normally when underboost?

For example, in the stock setup the pcv valve, brake booster, fpr etc ect, all run off vacuum directly from Intake. When you change to a boosted setup, I've gathered from drawings only (and I've been searching now for 2 hours with a crap load of reading but found the best help from the pictures of vacuum manifold installs), that you only need one feed from your intake manifold to a vacuum manifold. Than from there, it branches to your other systems. So now that your vacuum manifold is seeing boost being that its attached to your intake manifold/throtlebody, does that cause any complications on those devices that typically opperate in vacuum? Also, would hitting higher boost levels affect the operation of those systems aswell?

Thanks in advance for your input.

1fastlude1

no the only thing it would effect is your power brakes but who is braking at full boost, so no there are no complications

Crx Jimmy

usually you would run a catch can and remove the pcv system because there could be problems with that. Other than that it should be fine. the brake booster stores vacuum and will be fine unless you are boosting and braking at the same time

97grnrs

there is a check valve in the brake booster line.

AWDstylez..

Like the other guy said, the PCV has to go otherwise you'll be pressurizing the crank case. Aside from that you have nothing to worry about.

rorik

You might want to put a 1 way valve in line with part of the evap emissions system..

Contrary to the above post, you should run a pcv valve unless you like your oil black in 500 miles. Just make sure it doesn't flow in reverse, so you don't bleed boost into the crankcase. A good quality metal valve (most '80s hondas) won't flow backwards.

1fastlude1

no the pcv will not presssurize the crankcase from booat IT HAS A CHECK VALVE IN IT

91civicDXdude

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 1fastlude1 &raquo;</TD></TR><TR><TD CLASS="quote">no the pcv will not presssurize the crankcase from booat IT HAS A CHECK VALVE IN IT </TD></TR></TABLE>

boost (instead of vacuum or atmospheric pressure) from the intake manifold side will hold the PCV valve closed and pressure will build up in the crankcase.

rorik

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 1fastlude1 &raquo;</TD></TR><TR><TD CLASS="quote">no the pcv will not presssurize the crankcase from booat IT HAS A CHECK VALVE IN IT </TD></TR></TABLE>
Watch where you direct that hammer, ********, I've personally tested various pcv valves, and most of the cheap plastic ones do flow backwards. Hence the boost bleeding into the crankcase.

rorik

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 91civicDXdude &raquo;</TD></TR><TR><TD CLASS="quote">

boost (instead of vacuum or atmospheric pressure) from the intake manifold side will hold the PCV valve closed and pressure will build up in the crankcase. </TD></TR></TABLE>

Obviously not ideal, once you have even a moderate level of power, the little oem vent on the valve cover (of course now vented to the atmosphere) becomes a flow restriction to the blow by, and now the pressure builds up in the crankcase.
This is solved by a catch can and its associated large diameter plumbing.

There are a lot of diagrams floating around on here about how to set up a catch can without the pcv valve, and that is retarded. To reiterate, eliminating a properly functioning pcv valve will eliminate the fresh airflow through the crankcase when the motor is out of boost (which dilutes the blow by), and your oil will get contaminated very quickly.


Modified by rorik at 5:19 PM 5/22/2008

mattsnooz

Awsome, thanks a bunch guys.

And yes, the pcv valve will be held closed with boost in your intake. I knew that anyways, so I don't know why I included that with my origional post. The pcv is a one way valve that allows the pressure and blow by in the crankcase to escape.

So what about the other air line that goes to your stock intake though (H23) (top left corner of valve cover) Whats the purpose of that air line? Does that need a vacuum, or will it just vent if I install an air breather in its place like I see on most setups (I know how others do things, but want to know why so I understand and learn)? I will probably just put an air breather in that spot to replace the air line, and than run a catch can setup from the stock pcv valve as advised.

Again, thanks guys, you've been a huge help!

rorik

You need to break out the factory service manual and read how the pcv system works. Or just read my quick explanation..
The pcv valve is basically a controlled vacuum leak from the crankcase to the intake manifold. When your intake manifold is at less than atmosheric pressure, (part throttle), that vacuum pulls air in through the little aforementioned hose on the valve cover from the intake tube, through the crankcase, and into the intake manifold via the pcv valve.

This dilutes the blow by in the crankcase with fresh air. That is the real function of a pcv valve, not what you wrote.

At 0 manifold press (full throttle normally aspirated) there is no real pressure difference across the pcv valve, so it closes and then the blow by pushes itself out of the the little tube on the valve cover, and is inhaled through the intake tube. If you look at the intake tube, you'll see the evidence of this.
Technically, as far as the oem non turbo requirements, there is no reason for the oem valve to be a 1 way check valve. I Highly recommend checking this yourself, try to blow air through the valve the wrong way. Don't listen to people's bullshit about it, just double check this yourself. Not all valves work equally well, Esp if it is the 2$ autozone special. I have personally tested multiple valves and found several of them to flow about the same in either direction, wtf.
Now, with forced induction, your goals are to not pressurize the crankcase, preserve the part throttle oem pcv function, and not allow the motor to inhale oily crap from the blow by, which lowers your octane and can cause engine damage.
You can achieve these goals a few different ways..but I'm done writing for now.

B20EF

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rorik &raquo;</TD></TR><TR><TD CLASS="quote">I Highly recommend checking this yourself, try to blow air through the valve the wrong way. Don't listen to people's bullshit about it, just double check this yourself. Not all valves work equally well, Esp if it is the 2$ autozone special. I have personally tested multiple valves and found several of them to flow about the same in either direction, wtf. </TD></TR></TABLE>

I agree, I accidentally broke mine on my GSR. The old one didn't allow any air to pass through one way, but my new one which is an OEM replacement from Honda does allow a little bit of air though.

Even they can't get it right all the time

SovXietday

Replace the PCV system with a catchcan.

Any and all lines that originally run from the valve cover to the intake manifold/intake should be either left open or routed into said catchcan. Otherwise you'll pressurize the crankcase. Any nipples on the intake manifold that you don't know what to do with either use them for a wastegate/BOV source or cap them off.

Vacuum distributions blocks are better known as a good boost source for all of your BOV and wastegate needs.

If it's connected to your intake manifold, it will be pressurized. Make sure that anything connected to your intake manifold or IC piping by rubber hoses do not connect to the valve cover or catch can.

Make sure your catch can is vented to atmosphere and not a sealed one.

That's about it.

thorclark

Im boosting my hatch soon. I was just reading around but. This is interesting so for a good turbo setup you should have a oil catch can? Dont mean to jack the thread. Just trying to bring some knowledge to myself.

SovXietday

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by thorclark &raquo;</TD></TR><TR><TD CLASS="quote">Im boosting my hatch soon. I was just reading around but. This is interesting so for a good turbo setup you should have a oil catch can? Dont mean to jack the thread. Just trying to bring some knowledge to myself.</TD></TR></TABLE>

Yessir, catchcan is a good idea unless you like blowing oil all over your firewall like I do.

mattsnooz

Perfect.

Thanks again everybody.

all around (virtual)