I am doing an fmic setup, so I thought it'd be a good oppurtunity to reroute the hoses etc and make it look cleaner. I have a tophat intake plenum, so no crossover the valve cover, and I'd like to keep it free.

heres a picture of one of the oil breather? lines. Its a one way check valve? not sure if thats what its called, but i blew on it and it only goes away from the valve cover toward the intake plenum (stock one). My question is, on the rb25, theres a number of oil breathers including this one, which ones are ok to reroute? I plugged my intake hose going to the turbo, and am gonna run one of those breather filters to the drivers side oil thingy (the one that "t"s on the valve cover. Im going to leave the line that goes across the drivers side to the passenger side. I was hoping to put the one thats on the side of the valvecover (not top) to the hose which connects under the intake plenum (the one with the one way check valve pictured below)

I think this was discussed before but i'll explain again. That check valve is the PCV valve. It should connect to the manifold. During vaccuum it will suck out the oil vapors from the rocker covers and send it to combustion. When you get on boost the pcv valve will close and the rocker covers are then vented through the nipples on top into the intake duct. So your setup is fine. if you want you can run a catch tank between the pcv valve and the manifold. That'll collect most of the oil getting into the combustion chambers

-Bluefire

chambers

Bluefire wrote:I think this was discussed before but i'll explain again. That check valve is the PCV valve. It should connect to the manifold. During vaccuum it will suck out the oil vapors from the rocker covers and send it to combustion. When you get on boost the pcv valve will close and the rocker covers are then vented through the nipples on top into the intake duct. So your setup is fine. if you want you can run a catch tank between the pcv valve and the manifold. That'll collect most of the oil getting into the combustion chambers

-Bluefire

: if you want you can run a catch tank between the pcv valve and the manifold. That'll collect most of the oil getting into the combustion Dont get lazy with it. do exactly what he said. USE THE CATCH TANK, you'll be supprise the next time you change your oil...and change it out every oil change also. Trust us

Let me ask a couple other questions on the setup to clarify my kinda scrambled post earlier

Plugged this hole in the intake pipe which usually goes to the picture below this one, Im going to use a breather on it.



The two hoses which come up from the intake manifold, the one near the firewall goes to the AICV valve.



Im thinking of routing whats connected to the aicv valve to the hole on the cold pipe pictured below

The second pipe, farther from the firewall going to the pcv check valve...



My dilema is that im not sure is that one hose under boost? From what i understand and your guys' earlier posts its ok but i just want to double double check.

I think you mean the air regulator not aicv. Ok here is how everything is supposed to route. You have one large vaccuum hose that goes from the coldpipe to aicv valve. Then you should have one medium size vac hose going from the aicv to the air regulator. Then another same sized medium vac hose going to the manifold. The aicv valve is the one with two plugs on it with an idle adjusting screw. The air regulator is unit underneath the manifold with only one plug on it.

So make sure that the lines are routed like that Coldpipe-->aicv-->air regulator-->manifold

Ok so now looking at your picture I believe one of the hose coming up from beneath comes from the air regulator and must go to the manifold. The other hose should come from the pcv valve and also go to the manifold. The nipple on the cold pipe should attach to the aicv valve via a large vac hose.

OK I borrowed this pic and obviously did a great job drawing it but would this setup work

both vents leaving the valve covers lead to the catch can (while still attached together with the middle tube) the one hose leaving the catch can and goes into the intake mani? Or should it go to the intake pipe after filter?

or this setup which we will call setup 2

you don't want boost going into the crankcase. Have to use #2 unless you have a check valve (pcv valve) inline

setup 2. you cannot use setup 1. infact you don't even need two hoses going to the catch tank. You can just use one since the rockers are connected together. Or you can run two lines and get rid of the line in between. You also don't even have to have a line going to the intake pipe. Just run a breather on the tank.

-Bluefire

yeah i realize now how setup 1 wouldnt work since it would boost the crank case, but I though you wanted to have the crank case under vacum so you would need the line hooking in before the filter? and thats true I guess you would only need on hose or disconnect the center hose and use both

Yes you want that crankcase to be vented, but when your on boost you tend to have a lot more blowby than during vaccuum. In fact when you start boosting high(over a bar) you will get a **** load of blowby. This of course will depend on how good your rings are too, but either way you don't really want all that oil going through your turbo, ,ic, ic piping, tb, manifold. I've seen a 240 boosting 1.6 bar that would blow out almost a quart of oil after 3 laps. In this case they had to actually drain the catch tank back into the motor so there'd be enough oil in it. Anyways its up to you really, but I would rather not have anything going into my intake except air

-Bluefire

if i ran the catch can between the hoses valve covers and turbo then it would catch this blow by? thats the point?

yes. nearly all of the oil you want to be catching from the catch can is going to want to go into your turbo. reason for this is, like stated above, the only time your pcv will be OPEN is when you have vacuum, aka idling.

by putting the catch can between your valve covers and the turbo is fine.

anyone thought about running catch canless? i was thinking about plugging both the PCV and the turbo inlet, and just put breather filters on the valve covers.

gawdzilla wrote:anyone thought about running catch canless? i was thinking about plugging both the PCV and the turbo inlet, and just put breather filters on the valve covers.

basically what im doing. i have a filter and have little to no blow by

i still wanna put a catch can cause it looks cool

I've got a greddy catch can for sale for $75 shipped if anyone is interested. brand new