silvertop PCV question

[gmacrae]

Howdy. Im wanting to replace the factory vent from the cam cover to the intake tube either with a little filter or a catch can with a filter on top. Couple of things im wondering about...

When the intake manifold is in vacuum (most normal driving) there is a small amount of air being drawn thru this tube (metered by the afm) and thru the pcv valve into the intake. Because of this, it makes sense that replacing the tube with just a filter or catch can with a filter will allow a small amount of un-metered air into the intake, possibly leaning out the factory rich tune... to me, it seems like this could be a good thing - anyone else have any thoughts?

What is the point of the PCV valve in an n/a engine? Surely the intake will never see more pressure than the crankcase anyway? Isnt the PCV valve is just a restriction when you're trying to get all crankcase gas out fast?

Gimme your opinions - cheers lads

Gene

[xsspeed]

What is the point of the PCV valve in an n/a engine? Surely the intake will never see more pressure than the crankcase anyway? Isnt the PCV valve is just a restriction when you're trying to get all crankcase gas out fast?

Gene

im a bit of a noob with engine stuff, so will try my best to answer what i think your question is,
im guessing the pcv is attached to the pipe that attaches to the intake hose.

The purpose i understand is to suck air out of the crank case as the engine will perform better under a vacuum (below atmospheric pressure)
the intake provides a lower static pressure area so the gases are drawn out of the cracnk case.

talk to the guy whose on the university sae car team, i forget his name. I know that they have redesigned their dry sump this year (tell him it was brad eyes' project) and have oversized the pump to create a vacuum.

[gmacrae]

Cheers man, i get all that, wasnt quite what i was asking

[AceSniper]

no you cant let any air in after the afm, it will be ass and stall alot.

Up the top center of the cam cover block off the lil pipe into the TB's run the pipe from pcv valve to catch can.

the vent at the end of the cam cover by the dizzy vent it into the catch can, block off were it goes into the intake pipe

[Matty104]

viewtopic.php?t=48498&highlight=catch

[gmacrae]

cheers matt and acesniper was intending to keep the pcv valve venting to the intake like stock but it seems the engine will really prefer having both vented out to a catch can, and not plumbed back (warwicks comments) - so thats the way ill go.

[Matty104]

i did my blacktop with both to a can with filter on top, and put stainless intake in (or just Block the hole in intake pipe) and blocked off the other end of the pcv valve by sealing a bolt into the hose, enging runs so much better and smoother now was worth the effort in my opinion,

[AceSniper]

you can keep the pcv hooked up if your runing blacktop ecu/map but that removes the point of doing this.

it will be sweet, if you get time clean ya tb's after now your not sucking oil n crap in

[gmacrae]

hooked it up like suggested, no probs. I also made up an alloy plate to replace the whole top half of the vacuum chamber too, with a single 6mm vacuum line into the centre for my idle 'ball valve' (instead of the 4+ factory lines that were all plugged (all idle-up/evap sh*t removed). Looks heaps tidier and the car seems to like it. Let me know if anyone wants a pic

[AceSniper]

give us a look

[gmacrae]

here ya go, definitely looks better than the ugly stock bit. I was only using one vac line into it anyway for the ball valve, IAC valve is buggered but these dont need cold idle compensation anyway if the ignition is good. Also got rid of the shroud around the injector wiring, replaced with loom shieth stuff - heaps tidier. Keep in mind im not running a/c or powersteering tho.