Rb26 Oil Control On Circuits

[bcozican]

Head drain to sump

Baffled sump

Breathers in cam covers to catchcan

Line from catch can to sump - if it doesnt drain back quick enough put a VDO oil scavenger pump in the line and run it off a missle switch that you turn on when your on the track/ need to

Ran mine like this on my rb22 for 4 years - same same ?

Edited March 12, 2013 by bcozican

[r33_racer]

Cheers for the offer. As of last time out at Wroo I think I have it sorted. The thing managed a 55.0 short circuit on tyres so old they had sparks coming off them.

The solution is to vent the blow by via a path that doesnt go through the back of the head. I think the most of the rest of it is bollocks - eg the Mines head baffles, tiny (<1.0mm) oil restrictors. Ofcourse venting the blowby is really just a bandaid, albeit a common one. It shouldnt happen in the first place but a relatively small amount of blowby appears to cause big probems in the RB's. There are no end of RB26 out there who have this issue but it isnt a problem as they are only driven on roads where it doesnt show up.

There is another discussion to be had about ring thickness, tension and selection - eg what forged pistons can I run and use Nissan rings?

Mate you are the first person to identify this as the real issue/fix that I have come across! I have been waiting for a while now to see who else would catch onto this.

I figured this out a while ago with our race car engines. When we build our engines we don't use Nissan rings, just the old school approach of 1/16", 1/16", 3/16" rings. We go one step further and run a second gap less ring and we run the second ring gap tighter then the top. With this setup we don't see any breathing at all. Breather can is dead dry, the filters barely vent any fumes at all, only a little while she is bedding in on the dyno. The rings get bed in hard and quickly on the dyno, loaded up and heat cycled a few times, works perfectly!

The venting of the sump and covers as has been covered before is an adequate band-aid fix, as is the mines rocker cover baffle setup. However, as stated these fixes simply alleviate the excessive blow-by carrying oil out into your engine bay and making a mess. The real issue is the poor ring seal you are getting which is causing all these issues in the first place. Get the engine to seal up and that will fix the issue!

The problem is no piston manufacturer makes their product to suit thicker rings (like std Nissan rings), they all use thin rings which just don't have enough tension or meat to handle the rigors of a blown engine. The only answer is to order custom pistons which isn't really that much more expensive, it just takes longer.

Maybe now people might start believing me if others on the forum start seeing it as a good thing. People these days are so skeptical, show them in person and they don't know what to think, but let them read it on a forum mixed up with a lot of bullshit and its suddenly taken as gospel! Its crazy!

[SimonR32]

Interesting, but then again myself (plus many other) have issues with the standard Nissan OEM rings.

Also you say that piston manufactures make thin rings with too little tension but the same design works with many other types of engines. The RB26 seem to have issues but the RB25's don't. Mind you the RB25's have a "VCT drain" which is actually a sump vent to the rocker covers...

[R32 Stuart]

I can't believe this topic still gets raised, it is very basic - run a breather front and rear of tapet covers, oil / air separater above tapet covers and return line back to sump - does not matter which side, with a super light one way valve and minimum 19mm hoses for breather systems (slows air speed). This will vary if you run 10 pound of boost or 30 - as I do. There is nothing wrong with JE, CP, or Nissan pistons - the ring width should not change the seal with correct end gap, will just reduce friction and life span. If you want 310kw you won't get much blow by, but if you do not do above, your engine won't last on the track. If you want 440kw and you pick the right bits, you can do 4 years with just oil changes, with track, hillclimb, sprints, time attacke etc. We have put several pictures of R32 and R33 system on SAU and other sites - many use it now, no complaints yet - I am with above the mines baffles and restrictors are bollocks, sump is definitely a plus if doing tracks, keeps temps down and adds to safety. Cheers Stuart

[r33_racer]

The fact of the matter is the radial width does change how well the rings seal. A thicker ring has more sealing surface area against the bore at any point while going up and down the bore, being thicker it has more tension and sealing ability on every cycle where expanding gas isn't helping push it against the bore, it can handle and transfer substantially more heat from the piston into the bore for cooling ultimately giving it a longer lifespan whilst keeping a much better seal (less blow-by) for that duration.

Your idea of a fix is just a band-aid solution like the rest of them and that may in fact be good enough for a lot of people. However there will be people who want to know what the real cause is and then fix it at its root. The most effective band-aid solution I have found is to run a single -12 vent from the inlet side of your sump pan and run that to your breather can, combined with your lines from the rocker covers that helps vent the excessive blow-by from the crankcase and head which stops excessive oil accumulating in the head (which previously could not drain to the sump via internal returns as the crankcase was in positive pressure) which would normally get carried out of the rocker cover breathers into your catch can, filling it up and blowing it out all over your engine bay.

[r33_racer]

Interesting, but then again myself (plus many other) have issues with the standard Nissan OEM rings.

Also you say that piston manufactures make thin rings with too little tension but the same design works with many other types of engines. The RB26 seem to have issues but the RB25's don't. Mind you the RB25's have a "VCT drain" which is actually a sump vent to the rocker covers...

I wasn't saying the Nissan OEM rings are the ultimate setup. Just that they tend to seal better then newer age thin rings supplied with most forged pistons these days. No doubt if the stock rings are 10 years old they could be due for refresh.

What sort of issues do you have? Breathing issues?

Unfortunately every engine is different, some maybe more rigid then others and help provide a truer bore for the rings to seal on easier. The RB25 vct drain shouldn't act like a vent as the venting of the engine occurs on the inlet side not the exhaust side, that is the drain or return side for the oil. Its natural direction of flow is blow-by up the inlet side of the engine and oil drains down the exhaust side, however that is when the engine is running in a normal condition where it doesn't have excessive blow-by which is forcing itself up both sides so it can escape out the cam cover breathers. I guess in that situation an RB25 would have the slight advantage over the RB26.

Thin rings work fine in N/A engines, simply because they don't see the same high cylinder pressures and temps that exist in turbocharged/supercharged engines. It's similar reasoning why forged pistons for turbo cars are beefed up everywhere so they can handle the extra horsepower which presents itself in the form of higher pressure/heat.

All of what I have discovered is only from my own experience. We went from one engine with thin rings breathing heavily whilst making 600rwhp on alcohol to the same engine but with new pistons with the thicker rings to not breathing at all, and by all I mean no visible fumes and the can inside is perfectly clean and the air filters nice and dry instead of soaking with oil residue.

[dkbcleaner]

Hey guys just after some feedback on my setup. I have just rebuilt my 2.8 GTR with new rings ect.. and have followed all the oil control mods listed on the forum. The mods done are -

- 9 litre custom sump

- Nitto oil pump

- 1.1 restrictor

- Enlarged oil drains

- Mines cam baffles

- Hi Octane oil air separator to,

- JJR catch can drained to sump and vented to atmosphere

Now motor has done 2800km since rebuild and over the past week did a Sandown track day and DECA and I have noticed a oily residue over some parts of the engine, mainly the rubber hoses and oil leaking out of the air box and air filter soaked in oil vapour. The amount of oil that has leaked out of the air box underneath the air filter will probably be around 100ml. Now im not sure if the catch can is filling up with oil as its drained back to sump but after every session I checked the warmth of it and it did not feel 115 degree oil hot. You can easily rest your hand on it.

So what are we looking at here?

[gtr jet]

I'm new to this stuff but I get the basics of how it all works.

I've done one track day with no issues and am about to do my second at Easter.

I'm running a built motor with 325kw and basically all the factory plumbing (no catch can).

What's the best way to check if the car is breathing properly? Pull the filters off and check for oily residue on the intake pipes?

[Hadouken]

or check intercooler piping

[djr81]

Mate you are the first person to identify this as the real issue/fix that I have come across! I have been waiting for a while now to see who else would catch onto this.

I figured this out a while ago with our race car engines. When we build our engines we don't use Nissan rings, just the old school approach of 1/16", 1/16", 3/16" rings. We go one step further and run a second gap less ring and we run the second ring gap tighter then the top. With this setup we don't see any breathing at all. Breather can is dead dry, the filters barely vent any fumes at all, only a little while she is bedding in on the dyno. The rings get bed in hard and quickly on the dyno, loaded up and heat cycled a few times, works perfectly!

The venting of the sump and covers as has been covered before is an adequate band-aid fix, as is the mines rocker cover baffle setup. However, as stated these fixes simply alleviate the excessive blow-by carrying oil out into your engine bay and making a mess. The real issue is the poor ring seal you are getting which is causing all these issues in the first place. Get the engine to seal up and that will fix the issue!

The problem is no piston manufacturer makes their product to suit thicker rings (like std Nissan rings), they all use thin rings which just don't have enough tension or meat to handle the rigors of a blown engine. The only answer is to order custom pistons which isn't really that much more expensive, it just takes longer.

Maybe now people might start believing me if others on the forum start seeing it as a good thing. People these days are so skeptical, show them in person and they don't know what to think, but let them read it on a forum mixed up with a lot of bullshit and its suddenly taken as gospel! Its crazy!

Actually the nice folk at ACL make a piston that uses a 1.5mm upper and middle ring. They recommend 4.5 thou per inch of bore for end gap - works out to be 15.25 thou for a stock bore RB26.

[r33_racer]

The ACL/Ross pistons I have seen have the closest ring set. I have ACL/Ross's in my RB25 and they have a 1.2mm top and a 1.5mm second. Maybe they have changed it to a 1.5mm on both which is great news!

[djr81]

The ACL/Ross pistons I have seen have the closest ring set. I have ACL/Ross's in my RB25 and they have a 1.2mm top and a 1.5mm second. Maybe they have changed it to a 1.5mm on both which is great news!

Note the diffrence. Also note that the piston/bore clearance on the 26 piston is 0.1mm, not what is shown onthe data sheet,

http://www.aclperformance.com.au/NissanRB26DETTForgedPistons.htm

http://www.aclperformance.com.au/NissanRB25DETForgedPistons.htm

[fatz]

4500 bux for a fix here

http://www.skylinesaustralia.com/forums/topic/422263-rb26-complete-dry-sump-setup-4500/

[SimonR32]

Yes lots less oil. Before I put that line on the car had 2 x 3l catch cans. It still has them, but the 2nd one only catches the E85 vaper. I have recently added this new -10 line as a breather, which should fix all the breathing problems once and for all.

Have you ended up testing this set up yet?

Thinking of doing similar with mine. Plumbing rear oil drain using dash 10 line to rear of rocker cover (drilled and tapped) and dipstick using dash 8 to my catch can.

Just wondering if it cured or significantly helped with the issues?

Cheers

Simon

[sav man]

That car is still not together. But I ran the same setup in my car for Targa, and didn't have any breathing issues (oil was filled to the top of the hump), and I was reving it pretty hard. Before the event I drilled one of the oil restrictors out to get more oil into the head.

[SimonR32]

I usually manage to run from the top of the hump to the bottom after 2 or so 4 lap sessions. At the moment I'm then pumping it all back into the sump from the catch can but I would rather it just not get there in the first place

[SimonR32]

Ok I finally got around to getting mine sorted. Rear turbo oil drain (unused due to single turbo) plumbed into rear rocker cover fitting using dash 10 lines with a bit of gold tape to protect from manifold radiant heat and a dash 8 line plumbing from the dipstick to the catch can (getting fitting welded onto the catch can on Saturday).

Fingers crossed it works well

Edited June 20, 2013 by SimonR32

[sav man]

i'll be interested to see your results

[SimonR32]

i'll be interested to see your results

Track day Saturday 13th of July, will know then!

I got a little worried as there are reports the rear turbo oil drain vents a bit of oil as well (hence the fitting facing the baffles in the rocker cover rather than going in at 90deg and pushing into the crossover pipe or straight into the catch can).

[sav man]

I think the rear drain only pushes out oil when the turbo is still there. I had that problem with the nismo oil air separator. The blow by pushed the oil coming out of the turbo back out the oil air separator. Shoildnt be a problem with only 1 turbo