Oil Control In Rb's For Circuit Drag Or Drift

[ScreamerNewbie]

Just now, SimonR32 said:

Once again, how is that different to the oil/mist in the cam covers that drains back to the sump?

seeing as most engines only breathe heavy under hard load or high rpm ,i would think the majority of it is blown into the catch can.

either way just posting my thoughts on why i dont think it should go back to the sump. what would be the benefit of it going back to the sump?

[ScreamerNewbie]

1 minute ago, SimonR32 said:

The question is, is that ethanol affecting the oil or water condensation? and is that straight after driving the car or because you left warm oil sit in the catch can? 

Also nice and dandy for straight line stuff, that's never been the issue... Trying hammering around a Racetrack and you will see why it's better to have oil from the catch can drain back into the sump rather than no oil in the sump.

I'm also going to take a bet that my car not only survives Racewars and Powercruise weekends (and years and years of them) but also is more than happy to lap tracks running 2 bar with no issues

no way thats water condensation effecting the oil like that, the water and fuel can generally be seen sitting ontop of the oil when drained. 

fair call, not sure how the time attack fellas do it, but even if you have windage trays, baffles, correct breather setups and a correctly vented sump and all the rest and you still manage to EMPTY a sump? theres a bigger issue to your setup than draining a catch can back to the pan.. IMO

obviously everyone has their own opinions, i am showing people why i wouldnt do it, they can chose for themselves.

 

 

[djr81]

6 hours ago, ScreamerNewbie said:

no way thats water condensation effecting the oil like that, the water and fuel can generally be seen sitting ontop of the oil when drained. 

fair call, not sure how the time attack fellas do it, but even if you have windage trays, baffles, correct breather setups and a correctly vented sump and all the rest and you still manage to EMPTY a sump? theres a bigger issue to your setup than draining a catch can back to the pan.. IMO

obviously everyone has their own opinions, i am showing people why i wouldnt do it, they can chose for themselves.

 

 

You don't empty the sump.  But you can easily put enough in a catch can that firing over kerbs splashes oil everywhere (out the breather) and makes a mess.  So it works better with an empty catch can.

The oil is invariably stinking hot anyway.  Hot enough to boil off any ethanol (if that is what you are running) and water.  Also to burn the crap out of your hands when you spill it after touching the stinking hot engine/radiator hoses etc etc. Sure you can wait until it cools but then you lose half your track time.

Anyway point is if you are thinking of changing oil do it AFTER the track day.  Because what you are seeing is condensation.

[ScreamerNewbie]

i guess the difference is when ya on a track you change the oil that regularly anyways where as a street car not really

[SimonR32]

21 hours ago, ScreamerNewbie said:

no way thats water condensation effecting the oil like that, the water and fuel can generally be seen sitting ontop of the oil when drained. 

 

14 hours ago, djr81 said:

Anyway point is if you are thinking of changing oil do it AFTER the track day.  Because what you are seeing is condensation.

Also good point Richard makes about the water/ethanol boiling, I always drive my car to the track before thrashing so anything that could be potentially hazardous to the engines health with likely be gone by the time any thrashing occurs 

[GT-R David]

I'm going to answer my own questions in here, just for future reference, IF someone uses the search button.

 

 

Does anything speak against this setup:

-Hose from right cam cover to catch tank

-Stock Hose from left to right cam cover

-Properly baffled Catch tank vent to atmosphere

And here comes the part I didn't find anything in this thread:

-Hose from AN10/12 fiitting from sump (above oil level on intake side) to existing left cam cover connecting point (which normally goes to intake before turbo).

Should do the trick same as going directly to the catch tank, am I right?

So I can use the existing port on the cam cover, don't need to modify my catch tank and it is a really high point (maybe less blow by than going directly to catch tank)

 

People go from oil cap to sup to ventilate the head

having the vent in the low side of the head( left side to drivers side sump) to the sump seem stupid but give it a shot tell us your results

 

Haven't driven the car that much this year, but seems to work fine.

Has Tomei orifice, Tomei pump, breather from right cam cover to catch tank. Sump breather from right side of sump to left cam cover.

Baffled and enlarged sump. Overfilled to top of "H" mark on dipstick

No oil pressure drops anymore when accerlerating hard.

 

 

How much oil pressure is to much?

My RB28 has Tomei pump, 1.5mm head restrictor, 0.8mm turbo banjo bolts, 0,045mm main bearing clearance and 0,050mm conrod bearing clearence.

Tomei oil pump is at factory setting (max pressure) at the moment.

 

My Greddy digital gauge showing up to 7.5 bar on hot engine at 5500rpm with the 15w40 running in oil.

Will go back to 10w50 soon.

 

 

Seems fine at cold idle (6 bar) and hot idle (3 bar) and normal driving with hot engine at 3500rpm (6bar)

 

Should I go down with the pressure?

 

I adjusted the pressure to stage 3/5 (single spring and two shims).

Max pressure is around 6.8bar now at 6500rpm. Still 3bar hot idle.

Cold idle is 4.8bar.

3500rpm is around 5bar now.

 

 

Everything with Fuchs Titan pro s 10w50

 

Really happy with the oil system now.

 

[fatz]

Oil pressure drops on acceleration you really f**ked

 

most people have the issue on left hand bend and big decel after a left hand bend

[Rb25/240]

On my rb25 s1 I left the front vct, 1.5 middle and blocked the rear just got it started last week and only ran it for about 10 mins and still have lifter noise. How long does it usually take for the lifters to pump up

[Rb25/240]

Or any info as in if it matters if u plug the middle or back oil feed in the block because I blocked the back one and alot of people are telling me it won't work that way so id like to know if I have to pull the motor out again to fix my misstake. Any info would be greatly appreciated

[bilk06169]

mate you only plug them if they are solid lifter .

[-S-]

Not sure if my eyes are playing tricks on me...

[GTSBoy]

What's your point/question?  The one in the bag clearly looks like it's bigger than either of the 2 in the block.  This is why god invented round feeler gauges.

[Kevin Johnson]

1 hour ago, GTSBoy said:

What's your point/question?  The one in the bag clearly looks like it's bigger than either of the 2 in the block.  This is why god invented round feeler gauges.

https://physics.stackexchange.com/questions/224523/why-does-the-pressure-of-fluid-increase-when-the-diameter-of-the-pipe-increases

 

If you have entrained or dissolved air bubbles in the oil supply then the marginally larger diameter will help keep the bubbles smaller and/or dissolved.  This allows the fluid to act more closely to an ideal fluid which is what the factory engineers envisioned whilst designing the engine.  See Henry's Law.

[GTSBoy]

Do you seriously maintain that Nissan engineers calculated the size of the restrictors in the head oil supply to expressly keep dissolved gases in the liquid?  Really?  That's bizarre.  Show me an SAE paper where that has been proposed as a mechanism to counter this (I think non-existent) problem.

[Kevin Johnson]

5 minutes ago, GTSBoy said:

Do you seriously maintain that Nissan engineers calculated the size of the restrictors in the head oil supply to expressly keep dissolved gases in the liquid?  Really?  That's bizarre.  Show me an SAE paper where that has been proposed as a mechanism to counter this (I think non-existent) problem.

I have examined the sump design on hundreds of different engines including numerous Datsun/Nissan engines.  It is very clear that a large effort went into the sump design of the RB26DETT.  My criticism would be the corporately dictated bulge in the rear sump floor that disrupts the flow as it does in other Nissan sumps.  The engineers have to make the best of that.

As far as SAE papers go, there are MANY that deal with air entrainment in oil supplies.  I scarcely think that Nissan engineers are ignorant of basic fluid mechanics.  SAE.org is your starting point.  SAE now provides several pages of the article for viewing prior to purchase. 

 

[-S-]

What's your point/question?  The one in the bag clearly looks like it's bigger than either of the 2 in the block.  This is why god invented round feeler gauges.

I thought my eye sight is poor but you're the first who kinda agree with me that the 1 in the bag is bigger. All the others mention they look the same. Mind u the 1 in the bag is from tomei so that's 1.5 mm and yes I just measured it...

I swear my engine is bone stock prior to this "rebuild" but who knows what this ecr33 was back in the days in japan... Lol

[Kevin Johnson]

The titular page shown here is a good start for budding engineers.  The investigated engine was also the subject of two MIT theses and subsequent SAE articles.  I purposely do not give the links or further information because it is extremely important that people be trained to do research rather than be served pablum.  Suffice it to say that the MIT theses can be downloaded and read in their entirety at no charge to the investigator.  The SAE articles are not duplicates of the theses, by the way, but do draw upon the research.

 

Just to whet your intellectual curiosity, the engine was originally designed by Porsche.  You can learn a lot about engineering by comparing how Ford and Porsche treated sump design differently.

 

Good luck in your investigations.

 

Edited February 19, 2018 by Kevin Johnson

[burn4005]

Kevin you can stop being a smart Cünt. We're talking about a flow restrictor

 

The restrictor is there to restrict flow. Not keep bubbles dissolved. What do you think happens once the oil has passed through the orifice into the head galleries.

Feel free to publish an SAE paper about burn4005 being a wanker.

Edited February 19, 2018 by burn4005

[Kevin Johnson]

I suggest you read a few of the SAE papers before commenting about how and why restrictors are used for head oil supplies.

I have been subscribed to this thread for many years now.  I spent a lot of time making thousands upon thousands of posts in other forums dealing with this general topic.

I will be quiet now.

 

 

 

Edited February 19, 2018 by Kevin Johnson

[GTSBoy]

Entrained air is not dissolved air.  The fraction of any entrained air that will actually dissolve into engine oil at the sorts of pressures we're talking about here is what?  1%?  2%?  So even if it was an unrealistic number like 10%, that still leaves 90% of any entrained oil staying as entrained bubbles, not dissolved into the oil and therefore not affected by any attempt to use an ever so slightly larger restrictor orifice to ever so marginally increase the static pressure in the length of the orifice to ever so slightly affect the tiny amount of air that may or may not spontaneously spring out of the oil.

Talk about finding a way to confuse the conversation.

I hereby re-inforce my earlier statement that I cannot believe that OEM engineers would choose to increase the diameter of an oil flow restrictor by 0.25mm or any similar amount just for that purpose.  I would strongly suggest that all your palaver about sump design being important for preventing air entrainment into the oil is about the sump and the oiling system overall.  Prevention being more important than the (imagined) cure.