PCV Valve - Who Knew?

Post by **lewd lude lover** » Fri May 15, 2015 7:36 am

I think vent to air and put a breather filter on your turbo inlet but I'm on a very different engine now

The main issue seems to be excess pressure so I would go with option 1.

Post by **JEBB4** » Fri May 15, 2015 9:46 am

I don't think you get a positive pressure going into the rocker at that pipe do you?

Thought it was negative pressure sucking the gasses out and recirculating them further into the intake pipe..
On N/A anyway??

bb1boy · Post by **bb1boy** » Fri May 15, 2015 9:50 am

@Donald, come sort this mess out.

Post by **Vtecmec** » Fri May 15, 2015 9:53 am

JEBB4 wrote:I don't think you get a positive pressure going into the rocker at that pipe do you?

Thought it was negative pressure sucking the gasses out and recirculating them further into the intake pipe..
On N/A anyway??

That's right, it's a passive intake, driven from the vacuum that comes from the PCV side.

Post by **NafemanNathan** » Fri May 15, 2015 10:03 am

It's both positive pressure created from gas buildup under the head and negative pressure from the intake manifold sucking that creates the need and direction of circulation. The feed from the air intake pipe on an OEM setup simply aids the cycle.

The air intake pipe feed isn't going to create any detrimental pressure, but it will be a positive pressure due to the draw and direction of flow created by the throttle body opening. I was just stating that if the PCV was to be blocked the only escape route for the gases is back down against the flow from the air intake pipe, so there will be a constant battle between the two pressures and the head will never be as free of the gas as it should and could be (in that situation).

Whereas in the same situation of a blocked PCV, if there's only a breather filter on the other side of the valve cover, the gases can escape easily and there will be 0 pressure, meaning less gas to gunk up the head.

You'll still obviously want to sort out the PCV as soon as possible though.

Post by **NafemanNathan** » Fri May 15, 2015 10:04 am

bb1boy wrote:@Donald, come sort this mess out.

bb1boy · Post by **bb1boy** » Fri May 15, 2015 11:01 am

I thought this was something he might like to get involved in..

..and Nafe, you are the king of emotionally expressive gif's

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Fri May 15, 2015 8:51 pm

If a straight vent to atmosphere was the best solution, that's what Honda (and other manufacturers) would have done - if nothing else, because it would also have been cheaper for them and something they could have charged for replacing at each service (the filter) after all...

Post by **lewd lude lover** » Sun May 17, 2015 2:26 pm

wurlycorner wrote:If a straight vent to atmosphere was the best solution, that's what Honda (and other manufacturers) would have done -

but for the illegal nature of venting oil and fuel vapor to atmosphere...... they do the whole system to cover the fact they CANT vent to air...

I think.

My Type-S · Post by **Carlosfandango** » Wed Jun 03, 2015 6:23 pm

Been having a slight hesitation in the 1st 2 gears low revs, so have bought a new PCV to see if it helps

I know this can be a grey area, but, is it worthwhile me fitting a catch can as well at some point...or is their usefulness just an old wives tale ?