Oil Control In Rb's For Circuit Drag Or Drift

[GTSBoy]

so read this thread for probably half my day. I can summarise it down to this

1. One of the middle oil feed is blocked and a restricter is put on the rear (VCT equiped RB25NEO)

2.Fitting an oil drain at the back of the head

3. Port matching the oil galleries to the gasket

Now there has been a discussing earlier in the thread regarding the side to which the placement of the drain line from the head to sump should be located. Mspeed/Japs seem like they're going via the intake side whereas SK suggest going via the exhaust side with the drain above the oil level. So up to this date which way would be sufficient for a street driven car with occasional track days. Didnt quite get to see a good conclusion between the two ideas. Or is there a better method for having a bit more control to the oiling issue and breathing.

The external head drain is not a drain. It is a vent to prevent sump gases having to come up through the in block/head drain. Thus preventing the gases from preventing the oil draining, if you get what I mean.

[KiwiRS4T]

I think ill just stick to getting a bigger baffled sump and maybe put restricter with no drain. Ive read nearly the whole thread and actually more confused.

You're almost there - follow Simon's example in the post above yours. Actually the bigger sump and restrictors will cover most of it. But while you have the sump off drill and tap (or weld if you're so inclined) two fittings as high as possible on the intake side of the sump. You can just cap or plug them for now and if you decide you need the two breathers later at least you won't have to pull the engine out again.

[350stato]

Ok, Confused as hell right now, I have an RB25 that will be running a few track days, (drift/circuit) It has a Nitto oil pump, crank collar, 2 x 1mm restrictor's, So do I run the oil drain from the back of the head to the cold side, high on the sump above oil level, rocker cover breather's to a catch can, catch can drain back to sump aswell? do I put a breather on the catch can? (Also need the car to be street legal) Will this work? I'm about to pull the motor to fit the oil drain in the head, Would like it to stay there once I put it back in

[KiwiRS4T]

Ok, Confused as hell right now, I have an RB25 that will be running a few track days, (drift/circuit) It has a Nitto oil pump, crank collar, 2 x 1mm restrictor's, So do I run the oil drain from the back of the head to the cold side, high on the sump above oil level, rocker cover breather's to a catch can, catch can drain back to sump aswell? do I put a breather on the catch can? (Also need the car to be street legal) Will this work? I'm about to pull the motor to fit the oil drain in the head, Would like it to stay there once I put it back in

You don't need the fitting at he back of the head. Two lines between the sump and a catch can would be good - one at the top of the can one at the bottom so it can drain if necessary. Follow the post above from Simon. To be street legal over here (and I suspect it is the same in Aus) you can't vent to atmosphere which is why I run a line back to the turbo intake. If you suspect there is excessive oil fumes in that line (a properly baffled catch can will hopefully prevent that) you will need to run a second catch can or oil/air separator in the line to the turbo intake

[350stato]

Oh ok, well that's good new's, saves removing the engine!!

[Pezhead]

So just about to add some -10 fittings to my stock sump and noticed that the ribbing in the sump only has just a few tiny holes for oil before it has to go over the "dam".

Wondering if anyone else has added any extra drains?

[SimonR32]

Look up the greedy trust sump extension instructions and they show you how to drill them out to larger holes

[Reese69]

simon is this a custom catch can or a purchased one with some mods or brought like this? if so where from

To do one better I just had my fittings welded today so I have photos

Sump on intake side is 2 x -10

Catch can has one -10 drain at bottom that will go to the sump, 2 x hose tails on top to go to cam cover breathers and one -10 that will go to the other fitting on the sump as a vent.

[KiwiRS4T]

You are best to get one custom made as very few off the shelf items have any proper baffling inside. Mine is plumbed the same as Simon's except where he has a vent I have a line going to the turbo inlet.

You could buy a 4L square surge tank and cut it up and modify it to suit.

http://www.ebay.com.au/itm/Oil-Water-or-Fuel-Catch-Can-or-Surge-Tank-Alloy-2-0L-/251408805028?pt=AU_Car_Parts_Accessories&hash=item3a8921eca4

[GOD12A]

Heya guys,

Massive (and multiple) breather tanks are overrated.

If a tank is baffled correctly (and has an oil drain), it can easily be under 1L capacity and feed clean air to pre-turbo in a closed loop system.

This makes mounting easier and forces some thought into the actual design of the baffles.

I'm not about to wax lyrical about air/oil separators or throw in my 2c about RB oil control as it's all mentioned in this thread at some stage or another.

But if you want to solve (or bandaid as best as possible) the issue and are in Sydney, PM me for a chat if you're bored.

Mark

[Reese69]

_{mmmmmmmmmm thanks - might try find someone local to help as i cant weld lol - i have a 25/30 going in soon so would like something like this done - as i dont think oil restriction is very good (i think)}

[GTRPSI]

So just about to add some -10 fittings to my stock sump and noticed that the ribbing in the sump only has just a few tiny holes for oil before it has to go over the "dam".

Wondering if anyone else has added any extra drains?

ImageUploadedBySAU Community1388286733.000952.jpg

ImageUploadedBySAU Community1388286757.667836.jpg

I drilled ours out larger and added a couple of extra holes.

I also tapered the in side (rear side) to help flow.

We also have 2 dash 10 fittings welded to the RHS on a high octane cast alloy sump extension.

[r33_racer]

Just to clarify if you are draining back to the sump then it needs to be on the exhaust side of the block/sump. Inlet side will only ever vent.

[B-rice]

What if a one way valve is fitted to the line draining from the cylinder head to the sump. This could the located as close as possible to the sump so that no oil ever goes back up to the head through pressure from the sump.

[SimonR32]

Just to clarify if you are draining back to the sump then it needs to be on the exhaust side of the block/sump. Inlet side will only ever vent.

Not while in vacuum?!?

Mine seems to be draining to the inlet, unless it's actually not filling the catch can in the first place any more.

[KiwiRS4T]

Just to clarify if you are draining back to the sump then it needs to be on the exhaust side of the block/sump. Inlet side will only ever vent.

Not so. I have clear evidence that my catch can is filling up and draining. Anyway its quite impractical to run a drain round to the exhaust side.

[GTSBoy]

Drain is easy. If paranoia about windage takes possession of your brain, just put the bottom end lower than the oil level. There isn't actual positive pressure in the sump that pushes oil up a drain into a catch can. If the catch can is up high enough then there is a head of oil to push it back down into the sump. That's kind of the point.

Too many people imagine too much half arsed physics when thinking about this stuff.

[r32-25t]

So just about to add some -10 fittings to my stock sump and noticed that the ribbing in the sump only has just a few tiny holes for oil before it has to go over the "dam".

Wondering if anyone else has added any extra drains?

ImageUploadedBySAU Community1388286733.000952.jpg

ImageUploadedBySAU Community1388286757.667836.jpg

factory those holes don't exist, they are drilled in there when after market sump baffles are fitted

[GTRPSI]

No they (the ones under the 4wd shaft tube) are there in GTR sumps, albeit very small holes.

The idea is you open them up and add a few extra ones if you like to help oil drain back, the factory ones are tiny and struggle to keep up.

About the holes in the side of the sump on the intake side of the sump, they are pressure relief ports, no need to put the rear breather behind the head, your releasing pressure straight out of them so it does not travel upwards towards the head which fights the oil trying to travel downwards.

One of them can be used as a oil drain if run into the bottom of the oil catch can, blowby pressure when present will blow through the oil if oil is present in the can and still be a breather, when there is no crakcase pressure when driving normally or backing off it will flow back into the sump on that line.

One large fitting on top of the catch can can vent to atmoshpere or better still run the large line between your filter and turbo inlet, when driven hard there is some vacuum created there which will help draw the blowby gasses out of the catch can, helps to add vacuum to the catch can to enhance the blowby scavenging effect.

Some old school V8 setups even use to run a vacuum port off the exhaust headers, the line was welded in at a angle to the header for maximum scavanging effect, a one way check valve was used to stop backfire from going up into the breather system and this helped to assist creating a vacuum to draw blowby gasses, however you want to be sure you have a free flowing exhaust that does not have back pressure when attempting that one.

I see it cleaner and simpler to use the airfilter to turbo pipe as a vacuum port.

As proof there is a vacuum there, note GTR's have a spring wire inside the rubber intake pipes between the airflow meter and turbo to stop the pipes from sucking in and restricting flow because of the high vacuum level when the turbo draws air, might as well use the free scavanging effect to draw your blowby out of the crank case after its been through the catch can to remove all oil from it.

Edited January 1, 2014 by GTRPSI

[r33_racer]

The only reason it wont be draining now is most likely because there is no more oil in there to drain as you have alleviated the blow by and oil control issue.

If it were going to be a drain it would only drain under no or light load situations, not under full throttle full power running.