Vaccum hose??

can i just plug the lil vaccum hose that comes from the bottom of the stock air inlet pipe? we made our own 3" and just wonderin if it does anything?

i think that you may find that it is a pcv line, not vacuum.

ZRS90sc said:

can i just plug the lil vaccum hose that comes from the bottom of the stock air inlet pipe? we made our own 3" and just wonderin if it does anything?

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Mine is capped off at the tube and i cut down the hose that goes across the engine and put one of those tiny breather filters on it. It works fine.

NMxr7SC said:

Mine is capped off at the tube and i cut down the hose that goes across the engine and put one of those tiny breather filters on it. It works fine.

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The only problem with doing that is when under vacuum your PCV system is open and drawing unmetered air into the intake. Normally the air going into the motor comes from that little tube you have disconnected and since it's normally getting air after the MAF the volume of air drawn thru the PCV valve has already been metered. It's pretty much the same as a vacuum leak, but small enough that it doesn't have much effect.

David

David Neibert said:

The only problem with doing that is when under vacuum your PCV system is open and drawing unmetered air into the intake. Normally the air going into the motor comes from that little tube you have disconnected and since it's normally getting air after the MAF the volume of air drawn thru the PCV valve has already been metered. It's pretty much the same as a vacuum leak, but small enough that it doesn't have much effect.

David

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I thought the PCV was on the pass. side. I figured the driver side one was just a breather. Wouldn't the venturi effect cause air rushing through the intake pipe to pull air in through that vacuum line? I'm not being a smart ***, i've actually always wondered what it's purpose is. Does the PCV valve allow hot air from the engine directly into the intake? Would I be better off if I capped the driver side vacuum line from the valve cover altogether? Basically, How does the system work both driver and pass. side valve covers? If I need to hook that hose up again i will have to get an elbow to my intake pipe since i have it turned almost 90 degrees from the stock one.

NMxr7SC said:

I thought the PCV was on the pass. side. I figured the driver side one was just a breather. Wouldn't the venturi effect cause air rushing through the intake pipe to pull air in through that vacuum line? I'm not being a smart ***, i've actually always wondered what it's purpose is. Does the PCV valve allow hot air from the engine directly into the intake? Would I be better off if I capped the driver side vacuum line from the valve cover altogether? Basically, How does the system work both driver and pass. side valve covers? If I need to hook that hose up again i will have to get an elbow to my intake pipe since i have it turned almost 90 degrees from the stock one.

Click to expand...

Drivers side valve cover has a breather that looks like a PCV valve but it is really a plastic elbow. The hose from this breather is what connects to the air intake tube (between the MAF and TB).It is the intake or breather side of the PCV system.

The PCV valve is located on the passenger side valve cover and is connected to the the back of the intake plenum (part between the TB and Supercharger inlet). When the engine is operating under vacuum the hose that is connected to the PCV valve on the passenger side draws in the crank gasses and a nice oily mist (that's where the oil in your IC tubes comes from).

Since vacuum is sucking the air in and the engine is sealed the hose attached to air intake tube has a small amount of suction. The only time when air might travel the opposite direction is if your engine has excessive blow by under boost and the resulting crancase gasses are more than the PCV valve can handle. If that happened there would also be a small about of oil inside the air intake pipe. And your dipstick might pop up and blow oil on the motor.

So the driver's side is air going into the crankcase and the passenger side is air coming out of the crankcase.

David

You can drill a hole in your new intake pipe and simply use a rubber grommet to re-insert that pcv line (I used a short 90deg plastic vaccum elbow and trimmed one end so it was virtually flush inside the intake pipe). Alternately you can put one of those small K&N breather filters on the end of the existing pcv hose and just tie it off next to your MAF.