Oil Control In Rb's For Circuit Drag Or Drift

[iruvyouskyrine]

Read this roller coaster of a thread from front to back, what a journey. It seems like KiwiRS4T's setup utilising 2x sump fittings on the INTAKE side, and running each cam cover to a catch can is about the most well set up way that everyone can agree upon. I couldn't help that i had seen something like that before.

Edited March 13, 2014 by iruvyouskyrine

[Jazzadub]

If by head you mean catch can then yes.

The goal is very simple, relieve pressure in the crankcase.

Whether people think what they have installed is a drain or breather is irrelevant, improvements in oil return will be noticed when the pressure in the crankcase is reduced.

[Jazzadub]

Case in point, look how high in the "catch can" or breather tank the lines to the sump are.

They are obviously not drains but breathers, looks like a great setup.

[iruvyouskyrine]

If by head you mean catch can then yes.

The goal is very simple, relieve pressure in the crankcase.

Whether people think what they have installed is a drain or breather is irrelevant, improvements in oil return will be noticed when the pressure in the crankcase is reduced.

Whoops, yes i did mean catch can, corrected it now.

Yes i understand that now. The two goals are to reduce the amount of oil entering the head, and equalize crankcase pressure.

The oiling issue is solved by selecting the appropriately sized oil restrictor/s that vary with each engine set up. What must be taken into account is the head that you are using, and the oil pump that you are using. Heads with hydraulic lifters (IE R33 RB25) require more oil in the head than heads with Hydraulic lifters (RB26, RB25 NEO) and as such larger restrictors (IE providing less oil restriction) are used in those engines.

Here is a slight update on the original Skydneykid table created way back in 2006. It is pretty much exactly as it was just more user friendly and now includes the NEO. I left the RB20 off the table as nobody seems to be interested in them RE oil control issues, questions about them were asked nowhere near as frequently as RB25/26. They can be added back in if you wish.

The other issue is that of crankcase pressurization. The steps taken to achieve this are drilling out the oil returns in the block to 10mm, and giving them a chamfered edge to promote oil drainage. To displace the oil that is in the head, air must be moved into the head allowing the oil to drain (I am going to use the 'turning a drink bottle upside down' analogy here even though its not 100% accurate i think it gives everyone a good idea of what is going on) Increasing the oil drain cross-sectional area by drilling not only promotes oil drainage but gives air a larger path to travel up into the head, which increases drainage yet again.

A Combination of these two mods is a very good start to sorting out the problems associated with RB oil control, and should be the starting point for anyone looking into this.

A good catch can setup will help even further by acting as an equalizer for crankcase pressure and catching any oil that would otherwise be making its way back into the engine. I will use the method that KiwiRS4T has mentioned and others seem to be using with success. Both cam covers are individually run to a catch can mounted at approximately battery height in the engine bay. 2x -10AN fittings are welded onto the sump above the oil level in the sump. One is run to the highest point in the catch can, and the other run to the lowest point. The catch can can then be either vented to atmosphere, or run to another catch can that does the final oil/air separation before being piped back into the turbo intake.

All of the things mentioned above should be supported by other basic modifications such as

• Baffling in the cam covers, whether it be mines baffles or something similar
• Trapdoors in the sump to keen a consistent oil pickup
• Increasing the capacity of the sump
• Using an oil cooler

Even better control of oil would be done by having

• A Nissan N1 oil pump, or any aftermarket item (Nitto, Tomei etc)
• Fitting your standard nissan on N1 pump with billet gears (Reimax, Nitto etc)
• Fitting a crank colllar to your crankshaft to widen oil pump gear engagement
• Running an ACCUSUMP accumulator to control split second oil pressure loss and for the benefit of pre-oiling

Pics below of what SimonR32 has done with his catch can, which is what i was trying to explain in the diagram above.

If you cannot be bothered reading through the entire thread then read these posts, as i feel that they are some of the most important in the thread to get an understanding of what is actually happening inside the engine, which in turn is able to help us create a way in which to solve these problems.

http://www.skylinesaustralia.com/forums/topic/110680-oil-control-in-rbs-for-circuit-drag-or-drift/page-49#entry6798597

http://www.skylinesaustralia.com/forums/topic/110680-oil-control-in-rbs-for-circuit-drag-or-drift/page-49#entry6798648

http://www.skylinesaustralia.com/forums/topic/110680-oil-control-in-rbs-for-circuit-drag-or-drift/page-50#entry6929479

http://www.skylinesaustralia.com/forums/topic/110680-oil-control-in-rbs-for-circuit-drag-or-drift/page-53#entry7157413

http://www.skylinesaustralia.com/forums/topic/110680-oil-control-in-rbs-for-circuit-drag-or-drift/page-54#entry7159347

http://www.skylinesaustralia.com/forums/topic/110680-oil-control-in-rbs-for-circuit-drag-or-drift/page-54#entry7181463

http://www.skylinesaustralia.com/forums/topic/110680-oil-control-in-rbs-for-circuit-drag-or-drift/page-55#entry7208766

All the information in this above guide is purely my own thoughts/experiences on the whole RB oil control issue. Please do not take it as gospel and follow it to the letter. As always do your own research and come to the conclusion of what will suit you best based on your own setup.

Big thanks to everyone who posted in this thread.

[Jazzadub]

Great post, I think that sums it up nicely!

[Looney_Head]

awesome post, what are peoples thoughts on catch can design, and breather size? for breather size is it biggest is best? for both cam cover and sump breather?

[89CAL]

I have a pro flow catch can. Baffled 2L with cam cover breathers into the side, intake pipe hose onto the top, drain on the bottom baffled inside. Pretty good little catch can

Ive had no oil control issues as yet. Engine still has all the oil I put in it

[djr81]

Good post. Couple things:

I did the same as listed but if you use a check valve (you take the spring out of it) you can just put the oil back into the sump on the drivers side if you dont want to plumb it back into the turbo intake. So my sump looks bit like Simons just with three -10 fittings, not two.

The other half of the issue is blowby control. Cant emphasise this enough. The less gas you have going into the sump in the first place the less of an issue you will have.

[djr81]

Oh and if you do run it like Joshes diagram the catch can must be sealed otherwise you be sucking fresh air downstream of the AFM's if you are running them.

[34GeeTeeTee]

Sweet! Getting my catch can setup made soon! New sump is on and looks the goods, extra capacity, baffles/gates yada yada

[iruvyouskyrine]

Sweet! Getting my catch can setup made soon! New sump is on and looks the goods, extra capacity, baffles/gates yada yada

Fittings in the sump?

[iruvyouskyrine]

Yeah thanks all. The thread was a shitfight so I thought it was a time for a summary. I will probably edit it in a week or two once everyone has had their say.

Good post. Couple things:

I did the same as listed but if you use a check valve (you take the spring out of it) you can just put the oil back into the sump on the drivers side if you dont want to plumb it back into the turbo intake. So my sump looks bit like Simons just with three -10 fittings, not two.

The other half of the issue is blowby control. Cant emphasise this enough. The less gas you have going into the sump in the first place the less of an issue you will have.

There was talk about a check valve but I didn't really think it was an absolute necessity, considering the standard Nissan setup has oil vapours returning into the air intake. With the setup as it currently is I would suspect that there should be only very very small amounts of oil entering back into the engine. Is it a good idea, I would say yes, but I wouldn't say it is a necessity.

Also I neglected to talk about blowby control, but will add it into the post soon. Isn't it funny that people who slap together a backyard built engine and expect it to have perfect oil control just because "it's fully forged so it must be awesome" end up dumping litres of oil into their engine bay. When things like ring gaps and correctly suited rings are neglected and more money is spent on forged pistons/rods instead, you can't expect to keep your oil under control.

[34GeeTeeTee]

Shiiit.... Nope! Hmm

[ScreamerNewbie]

cannot suggest enough, accusump! only 300 for a basic 2L and it could save ur engine.

baffled, trap doored, extended sump with above and below oil -12 weld ons both in and ex sides. the 1s I don't use I simply cap (I like the options)

rear head drain to EX. side sump above oil (tee'd into turbo drain)

2x -12 sump breathers IN. side vent to catch can.

drilled block and head oil returns

block restrictors

rb26 covers with custom baffles

5L vent to atmp baffled catch can with twin filters with optional drain back (currently capped)

both lines from cam covers vent to can

both lines from sump vent to can

oil filter thermostat relocator with 25row cooler.

total oil volume 9L

rb25/30

[ScreamerNewbie]

id be putting some on atleast a single breather!!!!!!!

[djr81]

Yeah thanks all. The thread was a shitfight so I thought it was a time for a summary. I will probably edit it in a week or two once everyone has had their say. There was talk about a check valve but I didn't really think it was an absolute necessity, considering the standard Nissan setup has oil vapours returning into the air intake. With the setup as it currently is I would suspect that there should be only very very small amounts of oil entering back into the engine. Is it a good idea, I would say yes, but I wouldn't say it is a necessity. Also I neglected to talk about blowby control, but will add it into the post soon. Isn't it funny that people who slap together a backyard built engine and expect it to have perfect oil control just because "it's fully forged so it must be awesome" end up dumping litres of oil into their engine bay. When things like ring gaps and correctly suited rings are neglected and more money is spent on forged pistons/rods instead, you can't expect to keep your oil under control.

Yeah the bit to be careful of is that oil returns if there is too much oil will foul the afm's and cause the motor to run rich (it wont actually go bang, just lay black smokescreens everywhere). You can return it low in the sump but it needs to have a check valve otherwise oil can run up the line into the can which isnt helpful. Alternatively you can make sure the oil return is higher up but keep it away from the vents, for obvious reasons.

Also, for clarity, there appears to be some creep in the oil return drilling commentary. It has now become head and block???

But generally forged = awesome. Nothing could possibly go wrong. Ever.

[ScreamerNewbie]

Also, for clarity, there appears to be some creep in the oil return drilling commentary. It has now become head and block???

Well mate why would you drill only the block?? something can only flow as fast as its biggest restriction (we put restrictors in the block, theres like 7mm? of oil gallery and then our 1.3mm? restrictor, only 1.3mmDIA. of oil can flow

same principal for oil returns, if you don't drill the head oil returns too, the head oil returns will basically act as the restrictor making it pointless to drill ONLY the block.

[KiwiRS4T]

Good post. Couple things:

I did the same as listed but if you use a check valve (you take the spring out of it) you can just put the oil back into the sump on the drivers side if you dont want to plumb it back into the turbo intake. So my sump looks bit like Simons just with three -10 fittings, not two.]

What? Who is putting oil into the turbo intake? Oil drains back down one of the two breathers and catch can should be designed to capture oil from the fumes - if not you need a second catch can or air oil separator before the turbo intake. Why would you vent the catch can back to the sump? That would be a closed loop.

[Badgaz]

awesome post, what are peoples thoughts on catch can design, and breather size? for breather size is it biggest is best? for both cam cover and sump breather?

i tried to run the moroso pcv vent flutes that use the exhaust gases to create vacuum to vent crank case pressure...this failed...and created a rather smokey exhaust. then made an integrated oil catch can/window washer reservoir which i've had on since...only problem is that the breathers need to equalize the pressure going in otherwise your filter/filters will clog with oil...especially if your oil air separation does not work too well...like mine.

[djr81]

What? Who is putting oil into the turbo intake? Oil drains back down one of the two breathers and catch can should be designed to capture oil from the fumes - if not you need a second catch can or air oil separator before the turbo intake. Why would you vent the catch can back to the sump? That would be a closed loop.

There are two things going on here.

The most common way of setting up a catch can is to vent the blowby to atmosphere. The oil in the catch can itself goes back to the sump or you collect it and drain it later.

The post in Iruvyouskylines post, however, shows as point 5, the blowby gases returning to the motor the way Nissan intended. Which may well be more emissions compliant friendly. If you go with the second option and the oil is not under control you can get fouled afm's from oil in the blowby. I have had this on a motor with blowby and a Nismo "catch can".

No one is discussing sending the blowby gases back to the sump (which couldnt work anyway), just the oil in the catch can.