Rb Engines Venting Oil From Cam Box Breathers?

[Chris Wilson]

Circuit usage, on an RB25DET, same happened when I ran an RB26DETT. The emissions *rap is removed, so the intake isn't breathing crankcase fumes. The 2 cam cover stubs vent to a catch can. The valved breather that normally goes to intake plenum is blanked off. I run the oil about 1/8 inch over the full mark to help prevent surge. The oil loss is quite high, over a 20 minute on circuit session, on race rubber I lose about 1 litre or so of oil to the catch tank. The engine is perfect, no blow by, and has a Tomei oil gallery restrictor fitted in the gallery up to the head. I believe this is a common issue on race RB engines. I was thinking of making a shallow catch can to go OVER the plug cover area, between the cams, and either allow excess oil to drain back down into the breather stubs, or down a flexible tube into the dip stick tube (without the dipstick in it... )

What have others done to address this excess oil in the top end of the engine? Thanks.

[BADR33]

thats a pretty good idea you got there. you need to rember to still have that catch can venting as it releases excess crank case pressure from what i have been told.

my sky is non turbo but i have disconected those oil lines and it does run heaps better. im also not running a catch can at the moment. just a couple of little filters to catch the oil. but i will get a catch can when the new motor is in.

[BU5TER]

Hi mate I've noticed this catch can at www.nismo.com.au and I think if it was to be set up as in the pic but the 2 outer outlets actually be plumbed to the catch can it may do what you want

[carl h]

tried looking into running an external oil drain at the back of the head, seems that rb's suffer from poor oil drainage and i believe it.

when i looked at my rb20's head its amazing how any oil gets back into the sump as the oil return passages are blocked by the head studs.

[mid life crisis]

when i used to race holden v8s at speedway we used to tap into the side of the heads near the rear and run a drain back to the sump otherwise the rocker covers used to fill up with oil and pee out everywhere this used to fix that prob

chhers mid life crisis

[Denver]

tried looking into running an external oil drain at the back of the head, seems that rb's suffer from poor oil drainage and i believe it.

when i looked at my rb20's head its amazing how any oil gets back into the sump as the oil return passages are blocked by the head studs.

<{POST_SNAPBACK}>

Who has done this mod before?, and are there any pics of it?, curious to see what it looks like..

as for the breathing problem, im about to construct a breather setup for my 26 that will have both the cam cover lines venting into a box that will have a baffle plate setup to allow the oil and air to seperate, venting the air to atmosphere through a filter, but also running a return line from the bottom of the catch can back to the sump..