Oil Control In Rb's For Circuit Drag Or Drift

[leeroy_25]

I am getting ready to do my external oil drain from the head.. The notes say to put this into the sump.. Can I tee into the oil return in the side of the block where the turbo drains to instead? I am running single turbo. Or should I drain them both to the sump? I am running an rb26 with 4WD sump.

Thank you

Lee

[Kevin Johnson]

"I only have an RB26DETT pan (with AWD) to look at. In this pan, the witness marks from the oil indicate that it normally operates with 2 quarts or liters resident in the sump proper, the balance being in circulation. This is a fairly typical amount."

absolutely agreed....in road car use. as soon as you keep the revs up for a while they run dangerously low on available oil for the pick up.

you obviously have extensive experience with oil issues - how would you modify the sump for more reliable oil pick up??

Hi Duncan,

I apologize for the big delay but I have been super busy. If you look at the oil witness marks carefully you can see a huge triangular shaped effect that extends from the rear to the front of the engine. Get rid of the hump.

It is very obvious that an incredible amount of thought/serious-engineering went into the RB26DETT wet sump. What would I suggest? Get rid of the hump -- that was imposed on the designers. Make sure the engine sits level or very slightly tilted forward with respect to the pavement. The pan clearly indicates that oil pools in the back of the pan otherwise. This will destroy your engine in short order. I suspect this is also the genesis of the need for head drains. Old engine and/or tranny mounts might be to blame here.

I designed a scraper for the engine that removes oil on the downstroke prior to entering the complex triple layer windage tray setup.

If you modify the sump by removing the trans, I would go so far as to make a dummy axle-section and weld it in there.

Some pics of the scraper in situ; OEM components removed for clarity only, RB25 design is similar but covers more of the rotating assembly because the block casting is different:

[hpt_simon]

has anyone ever tired dry sumping, with scavenging from the head and turbos?

whould this be one of the best solutions?

im planing on doing this with a 6 stage pump. 3 to sump and 1 head 1 turbo.

thanks

simon

[Risking]

Yes there a heap of dry sump GTRs doing the rounds.

I have one.

Dont scavenge from the turbos. Oil coming from them is froth and wont be scavenged properly.

I use a barnes 5 stage pump. 3 scavengers from a multi baffled 1 litre sump pan and a final scavnger from the rear of the cylinder head.

I use -12 sump scavengers and a single -10 head scavenger. If you do it be sure to set-up the system with a good releif valve to make sure you have adequate vacum in the crank case.

One thing we struggled with in the initial set-up was getting negative pressure inside the sump. Things like rockercover half moon seals being sucked in and so forth was an issue.

Also ensure you have a well designed breather system for your tank, with negative pressure in the sump the tank will need to breath well.

[Kevin Johnson]

Set the pressure relief valve to 12 inches Hg as a good compromise.

Yes there a heap of dry sump GTRs doing the rounds.

I have one.

Dont scavenge from the turbos. Oil coming from them is froth and wont be scavenged properly.

I use a barnes 5 stage pump. 3 scavengers from a multi baffled 1 litre sump pan and a final scavnger from the rear of the cylinder head.

I use -12 sump scavengers and a single -10 head scavenger. If you do it be sure to set-up the system with a good releif valve to make sure you have adequate vacum in the crank case.

One thing we struggled with in the initial set-up was getting negative pressure inside the sump. Things like rockercover half moon seals being sucked in and so forth was an issue.

Also ensure you have a well designed breather system for your tank, with negative pressure in the sump the tank will need to breath well.

[ylwgtr2]

heres my head fitting

[ali-turko]

hey ylwgtr2 i like the way that yiu have done your head fitting look like your will have plenty of room between the head and firewall, did you make it your self or bought it??

where can i get one from,

[Piggaz]

^^^^ Very nice..."Almost" looks factory!

[ylwgtr2]

i have a CNC machine here at work...we made the block using that and with the tube i machined down a bit of solid on the lathe and drilled a hole and welded a thread on the end....it took about 20 mins to make up....i could have threaded the block and and tapped the pipe as well as screw cut the thread for the hose on the lathe....but 20 mins is all i had

Edited April 20, 2009 by ylwgtr2

[ali-turko]

do u wanna make me one ??

[Cjmartz2k]

I've read some interesting information from a well known and respected engine builder here on Okinawa. I'm interested in what you guys have to say about what he has to say since it's contrary to the common "knowledge" on the boards.

The following three pictures are of the additional crankcase vent. I first started doing this mod on the 26 in the mid 90’s. It’s a common mod for high rpm engines, so it was a no-brainer for the RB26. Soon thereafter, the Internet got a hold of it and speculation as to its function ran rampant. “Additional oil drain-back” became the consensus, and consensus became fact. Now it’s well known as the additional oil drain back mod… Then it became a fact that all the oil in the engine will pool in the head and the engine will blow if you don’t have it done…

Really? Let’s examine some facts. The RB26 has been lapping the Nurburgring starting years before the R32 came out in 1989. Lap after lap at full-boogie. Since then, the R33 and R34 have been lapping the same track. The N1 GT-R that races in the N1 class doesn’t have this mod done. Super Taikyu RB26’s don’t have this mod done. I can assure you that the RB26 does not have an oil drain back problem that warrants modification to implement an additional one.

Remember the videos I posted of the Porsche engines in the cradle that simulate a run of the Nurburgring to test the oil system? Nissan has the same thing.

So what’s the deal??

Blow-bye in ultra-performance engines. You get an RB26 up in the 10,000rpm neighborhood and lean on it with 2+ kg of boost and you have a blow-bye nightmare.

See, all but one of the oil drains back into the sump on the RB26 are on the left side of the block. When we examine crank windage, that’s the side of the engine where the crank counterweights, rods, etc., are moving in a downward direction, essentially “pulling” oil back down out of the head. In the right-rear of the engine, there’s another port. This port is on the “pressure” side of the motor, and windage blows up this passage, creating an actual suction on the drain-side of the motor.

At high-rpm, high-boost, blow-bye gasses can be so severe, that the single port on the right side isn’t adequate. Gasses are moving up all the ports, sometimes at high velocity. This effectively keeps oil from returning to the sump. What the large hose from the sump to the back of the head does is give the blow-bye gasses another path to the head, and allow the oil to return down the normal returns along the left side of the motor.

In a drag motor, if we accelerate forward at 1g, the oil in the sump will stand up at 45 degrees. It’d be neat to hear an explanation of how the oil in the head overcomes the laws of physics and somehow runs forward to the front of the engine. In a circuit/touge motor like this one, oil will indeed return down the hose to the sump, which is the reason it needs to be lower than the baffles in the pan; on that side of the engine, any oil returning will simply be picked up by the crank and added to the hurricane in the crankcase.

Discuss...............

[Ceffy]

I spent over $1000 getting my head overhauled and at the same time I had the oil galleries bored out and had the machine shop remove a rear welsh plug to allow a fitting to be used as a drain. I used a speed flow fitting then a pipe ran down to a "T" piece to the turbo drain to the sump. Heres some pics...

That blue thing is the fitting from a top view, rear of head.

Side views

[Kevin Johnson]

I've read some interesting information from a well known and respected engine builder here on Okinawa. I'm interested in what you guys have to say about what he has to say since it's contrary to the common "knowledge" on the boards.

Discuss...............

I think people miss a lot of information by cleaning parts before examining them. The RB26DETT clearly suffers from the same issue that affects the SR20 -- the projection of the torque converter access hump into the girdle.

I don't pull this stuff out of thin air. Toyota faced the same engineering issue with the 1ZZ and converted the 3-4 bay axial windage rotation into a horizontal rotation parallel to the pavement.

The engine that I examined also showed evidence of pooling oil in this area for an extended period of time -- that means the attitude of the engine was tilted rearward beyond the angle of the floor in the sump -- however slightly, it doesn't matter.

It is very plain that Nismo went to a great deal of trouble to design the wetsump. I am very sure that they would not introduce an angle of repose in the rear of the sump that would actively collect and subject pooled oil to the churning of the rotating assembly. After all, this is the exact failure mode of the Toyota ZZ engines when the 1G wetsump rating is exceeded. Talk to some windage engineers at the OEMs -- they examine oneanother's designs.

I think the root cause is old engine and tranny mounts.

[GTRsean]

I've read some interesting information from a well known and respected engine builder here on Okinawa. I'm interested in what you guys have to say about what he has to say since it's contrary to the common "knowledge" on the boards.

Discuss...............

An engine builder I talked to told me something along those lines too.

He has years of experience in all types of engines and also builds up race engines.

Main players in an engine, especially a forced induction engine.

Oil, oil returns/drains, blowby gasses, crank case ventilation etc.

Understanding the physics of whats going on inside your engine at high RPM/boost in certain applications will help explain what 'fix up's' will do/work to your engine setup.

I have mostly sorted my oil system for my mostly street car. I have done some things but not others.

Forged internals RB26DETT R33 block and crank

stock sump baffle and sump

R33GTR oil pump

Tomei oil restrictor 1.5mm

oil returns in head etc drilled out and rear returns die grinded out

Mines style cam cover baffles

just jap oil/air separator barrel

catch can in front of battery

I left the cam cover air vents open and took the car for a drive to see how much oil comes out of the vents, after fitting the baffles.

Looking forward the l/h breather spat a small amount of oil out.

The r/h beather had no oil come out.

Fitted the air oil separator on top of the engine and plumbed it all up. It's running full closed setup like factory, with clear piping and no sign of blowby oil =

Not the best setup, but I don't smell any oil fumes anymore due to it all being closed loop.

[Kevin Johnson]

I should mention that if you examine the head drain passages in an old Honda D15/16 head you will see that some have no lip while others do. This biases their function to oil drainage versus blowby passage. It is best to draw blowby away from the crankcase proper in any event. Look how Ford did that with the Zetec E. There are many compromises in engine design and you can see that at least some of them are packaging restraints.

[PSI Parts]

I'm curious to know if people have made a return line from their catch tank to the sump, where they plumbed it to?

As I don't want to use the turbo oil return, are there other options?

[PRO_32]

Tee it into the line going from the rear of head to sump

[Swiper the Fox]

The following three pictures are of the additional crankcase vent. I first started doing this mod on the 26 in the mid 90’s. It’s a common mod for high rpm engines, so it was a no-brainer for the RB26. Soon thereafter, the Internet got a hold of it and speculation as to its function ran rampant. “Additional oil drain-back” became the consensus, and consensus became fact. Now it’s well known as the additional oil drain back mod… Then it became a fact that all the oil in the engine will pool in the head and the engine will blow if you don’t have it done…

Really? Let’s examine some facts. The RB26 has been lapping the Nurburgring starting years before the R32 came out in 1989. Lap after lap at full-boogie. Since then, the R33 and R34 have been lapping the same track. The N1 GT-R that races in the N1 class doesn’t have this mod done. Super Taikyu RB26’s don’t have this mod done. I can assure you that the RB26 does not have an oil drain back problem that warrants modification to implement an additional one.

Remember the videos I posted of the Porsche engines in the cradle that simulate a run of the Nurburgring to test the oil system? Nissan has the same thing.

So what’s the deal??

Blow-bye in ultra-performance engines. You get an RB26 up in the 10,000rpm neighborhood and lean on it with 2+ kg of boost and you have a blow-bye nightmare.

See, all but one of the oil drains back into the sump on the RB26 are on the left side of the block. When we examine crank windage, that’s the side of the engine where the crank counterweights, rods, etc., are moving in a downward direction, essentially “pulling” oil back down out of the head. In the right-rear of the engine, there’s another port. This port is on the “pressure” side of the motor, and windage blows up this passage, creating an actual suction on the drain-side of the motor.

At high-rpm, high-boost, blow-bye gasses can be so severe, that the single port on the right side isn’t adequate. Gasses are moving up all the ports, sometimes at high velocity. This effectively keeps oil from returning to the sump. What the large hose from the sump to the back of the head does is give the blow-bye gasses another path to the head, and allow the oil to return down the normal returns along the left side of the motor.

In a drag motor, if we accelerate forward at 1g, the oil in the sump will stand up at 45 degrees. It’d be neat to hear an explanation of how the oil in the head overcomes the laws of physics and somehow runs forward to the front of the engine. In a circuit/touge motor like this one, oil will indeed return down the hose to the sump, which is the reason it needs to be lower than the baffles in the pan; on that side of the engine, any oil returning will simply be picked up by the crank and added to the hurricane in the crankcase.

The above quote is what ive been telling guys for years...its not an oil drain as such its a crankcase ventilation pipe to release pressure to allow the factory oil drains to do their job at higher than factory rpm and boost levels.

Edited June 28, 2009 by DiRTgarage

[DCIEVE]

In that case save the effort of tapping the head and send the sump breather straight to the top of the catch can along with the cam cover breathers.

Has anyone cosidered using a vacuum pump in the absence of the std pcv set-up?

Edited June 28, 2009 by DCIEVE

[Risking]

In that case save the effort of tapping the head and send the sump breather straight to the top of the catch can along with the cam cover breathers.

Has anyone cosidered using a vacuum pump in the absence of the std pcv set-up?

PLENTY of people do but not with RB's.

Your onto something there