Oil Control In Rb's For Circuit Drag Or Drift

[GT-RZ]

I honestly dont think you understand it, especially when you start talking about 30psi of vacuum, as relative to atmosphere 30 psi vacuum is impossible

It was an example. Any level of vacuum is possible although generally gauges will only show up to -14.7psi.

You need to read up on vacuum.

would you have prefferred to say 15inHG instead? I will not go in to vacuum but it is as endless as pressure.

You are reinforcing your comment that Zero pressure is that same as -15psi or whatever stupid comment you made.

Infact thinking about it i think you have confused yourself. atmospheric pressure is standarised at 14.7psi which is close enough to 15psi...

if you were to take away 15psi then you would be at around zero pressure, correct. is this what you are saying?

What is being said is the atmospheric pressure WITHIN the CRANKCASE is lowered to a negative pressure (vacuum)

If you have a system that is capable of removing 15psi of pressure then indeed the atmospheric pressure WITHIN the crankcase could be zero. That would depend on where the pressure was when it started (+15psi).

If you have a system that is variable and can KEEP the atmoshperic pressure at -15psi or 7.5inHG is you prefer then that is completely different, and is what i was reffering too. And would be over the top. The perfect system would keep the pressure between 0 and -1psi or 0.5inHG. IMO.

I think you have come unstuck when the word atmosphere came up. when i say atmoshpere within the crankcase that refers to a local atmosphere within the crankcase, not the earths atmosphere...

Edited July 3, 2009 by GT-RZ

[Adriano]

Yes, that is exactly where the confusion came from

[Boosted Zed]

Dirt Garage should be in an F1 team. They could use your talents of taking it up atm. Actually why not just start your own, rather than share all your good ideas?

[NYTSKY]

Being the only engine Paul built who tried this mod, i have to say no dramas so far.

I had the PCV disconnected at Powercruise and through all the limiter bashing circuit work, there was only ever a fine mist of oil on my plenum.

Still unsure whether it acts as a drain or a vent but it seems to work.

Now that it has a catch can setup similar to stock ( rocker covers to can to turbo intake) i virtually have no blow by whatsoever.

Could be good clearances but i wouldnt say that to your face Paul

[Swiper the Fox]

Dirt Garage should be in an F1 team. They could use your talents of taking it up atm. Actually why not just start your own, rather than share all your good ideas?

Ohh c'mon JP...having a go at someone who does some actual testing and working out whats happening instead of taking things as a given. You yourself do the same and share your findings on here and even are developing your own products to combat the things you have found is to be applauded. Why be so negative about me doing something you do yourself...it doesn't make sense.

The forum is such a good one because it helps people who don't have the money or resources to do it themselves and gain from guys like us who do the hard yards.

Don't get me wrong...im not saying that the rear head set-up is a bad thing to do...its just been a little mis-represented and is not a true indication of what is actually occuring inside that pipe.

Edited July 4, 2009 by DiRTgarage

[Boosted Zed]

Ohh c'mon JP...having a go at someone who does some actual testing and working out whats happening instead of taking things as a given. You yourself do the same and share your findings on here and even are developing your own products to combat the things you have found is to be applauded. Why be so negative about me doing something you do yourself...it doesn't make sense.

The forum is such a good one because it helps people who don't have the money or resources to do it themselves and gain from guys like us who do the hard yards.

Don't get me wrong...im not saying that the rear head set-up is a bad thing to do...its just been a little mis-represented and is not a true indication of what is actually occuring inside that pipe.

Who is being negative. Throw dirt in life you only lose dirt yourself.

[fatz]

im re-gigging my setup

i think ill run a extra breather to the dipstick hole now to give that a bash as well

although my heavy breathing may have something to do with my tolerances... seeing as the stock bottom rb30 in it at the moment just clicked over 400k

lol

[SimonR32]

Dirt Garage should be in an F1 team. They could use your talents of taking it up atm. Actually why not just start your own, rather than share all your good ideas?

http://www.youtube.com/watch?v=SVUekHmY87M

Edited July 4, 2009 by Cerbera

[GT-RZ]

Anyone got a pic of the m speed r34 intake side of the engine???? That will prove if they are using the head connection primariliy as a drain or a vent... If its higher than the centre of the crank it would certainly point towards more of a drain utilising the venturi effect... if not then more of an extra windage escape...

I would like to add that the connection to the head would not be as neccissary if you have a vent from the block directly... Anyone know where you can source some pneumatic one way valves? one that is adjustable and able to open at very low pressures would be ideal...

You could connect that from your vent on the intake side of the block (must be above oil level, dipstick would be ok) or from the breathers on the covers ideally coupled with the head attachment if you don't want a vent from the block. Then attach that directly to the TOP of your catch can that vents to atmo or even better to some sort of vacuum setup, or either plumbed in to intake (factory re-circ would work... and with the one way valve you would not need a BOV if you did not want one...) or exhaust to utilise natural vacuum (venturi effect).

That way you could guarantee no positive pressure is going to enter the crankcase from your escape (engine will make it's own negative pressures depending load of the engine) and it would allow rising positive pressure an escape!

Edited July 4, 2009 by GT-RZ

[Risking]

Being the only engine Paul built who tried this mod, i have to say no dramas so far.

I had the PCV disconnected at Powercruise and through all the limiter bashing circuit work, there was only ever a fine mist of oil on my plenum.

Still unsure whether it acts as a drain or a vent but it seems to work.

Now that it has a catch can setup similar to stock ( rocker covers to can to turbo intake) i virtually have no blow by whatsoever.

Could be good clearances but i wouldnt say that to your face Paul

I wouldn't call power cruise "circuit work" Take it out for a 20min flat nackers race at the front of the field and give it the real test.

I had never run external returns/vents on my wet sump engines. ( I do now just cause it cant be a bad thing) I did have a breather return to the sump. Super sprints, 4 lapers never had an issue. Give it shit for a 12-14 lap race at full noise and see how it goes, thats the only way to test a circuit cars breathing system period, having said that I did test mine and it didnt have any breathing issues but did break an oil pump the next time it went out.

[fatz]

its probabay only good good for a engine that was not run in properly or very old

either way i do it for the bitches cause at maccas they love some blow bye

BLOW!

suck the balls

[Risking]

For those interested with my dry sumps I block off the head to sump oil returns and run one good -12 scavenger from the rear of the cyl head. It lets me maintain much better control of the crank case neg pressure and the one scav off the rear of the head works perfectly. I dont care if there is too much oil in the head all the breathers are blocked off besides the one releif valve.

And yes I have tested and tested the dry sump system to come to the conclusion that this works.

[s13_Skyline_inside]

and with the one way valve you would not need a BOV if you did not want one...) or exhaust to utilise natural vacuum (venturi effect).

sorry but whats a bov got to do with crank case ventilation?

[NYTSKY]

I wouldn't call power cruise "circuit work" Take it out for a 20min flat nackers race at the front of the field and give it the real test.

It was 6 20min sessions, but yes i see your point.

[GT-RZ]

sorry but whats a bov got to do with crank case ventilation?

Well it depends on the setup really. if you had setup a venturi effect inside the intercooler piping (factory does not do this but...) then without a one way valve when the throttle is closed (which a bov is designed to vent) it could potentially push air down the wrong way of our vent and pressurise the crankcase, which we don't want.

Basically if you mounted your re-circ to utilise venuri effect you would be mounting it before or after the throttle body. If it is after the throttle body (ie inside the manifold given that it's a single entry throttle body) then you would not have as large a problem as it would not experience big issues due to 'refused' pressure. But if you have six individual throttle bodies it may prove difficullt to achieve this and the re-circ may have to be mounted before the throttle bodies, leaving it vulnerable to positive pressure once the throttle is closed.

So to your question a BOV would be beneficial if you mounted it before the throttle bodies because it is designed to release excess positive pressure. Bearing in mind if you just ran a one way valve you would not worry wherever you mounted it.

Think i explained what i mean?

Edited July 4, 2009 by GT-RZ

[drf76]

this picture pretty much explains it all, its a vent, how can oil drain back through there when one its tiny and two how i can oil flow from the rear of the head to the front of the sump under acceleration (drag) there isnt that much pressure of blow by in the head to be able to push the oil forward to the engine sump under accelaration anyway..i bet that all the ppl who do have this mod to the back of the head just do a test and vent it to a catch tank, they wouldnt have any more blow by issues compared to having it connected to the head, physics does lie simple...i dont understand the debate... both parties are essentially doing the same mod, adding a vent just putting it in a different place lol.

[Swiper the Fox]

this picture pretty much explains it all, its a vent, how can oil drain back through there when one its tiny and two how i can oil flow from the rear of the head to the front of the sump under acceleration (drag) there isnt that much pressure of blow by in the head to be able to push the oil forward to the engine sump under accelaration anyway..i bet that all the ppl who do have this mod to the back of the head just do a test and vent it to a catch tank, they wouldnt have any more blow by issues compared to having it connected to the head, physics does lie simple...i dont understand the debate... both parties are essentially doing the same mod, adding a vent just putting it in a different place lol.

yes spot on. ive tried the hose on both sides and it works better on the RHS from my test results. Ive never connected it to the rear of the head though. Weird that when connected to the LHS it actually had oil filling the can from the rear turbo oil drain...and on the RHS only vents sump gas and no oil.

[drf76]

yes spot on. ive tried the hose on both sides and it works better on the RHS from my test results. Ive never connected it to the rear of the head though. Weird that when connected to the LHS it actually had oil filling the can from the rear turbo oil drain...and on the RHS only vents sump gas and no oil.

id 100% agree with that as it would primarly be used a windage port on the rhs, and the only thing that puzzles me is that the your test show oil coming up, even though nissan used it as a factory drain for the turbo...weird, maybe the position of that port is not perfect but with turbo connected there must of been enough flow of oil to overcome the very slight pressure, at the end of tha day it is a return, otherwise the turbo wouldnt be able to return any oil which we all know would be impossible...soo all in all rbs need a restriction to the head, good returns and good venting...

dg..have u tried just venting the the crankcase as a sole mod or is the restrictor definetly needed aswell, ive been always wondering..

[GT-RZ]

this picture pretty much explains it all, its a vent, how can oil drain back through there when one its tiny and two how i can oil flow from the rear of the head to the front of the sump under acceleration (drag) there isnt that much pressure of blow by in the head to be able to push the oil forward to the engine sump under accelaration anyway..i bet that all the ppl who do have this mod to the back of the head just do a test and vent it to a catch tank, they wouldnt have any more blow by issues compared to having it connected to the head, physics does lie simple...i dont understand the debate... both parties are essentially doing the same mod, adding a vent just putting it in a different place lol.

This picture does not explain it all. if we had a picture of the intake side of the engine it attaches to we can make more educated guesses.

You clearly underestimate some laws of physics. In an engine as we accelerate the g force does increase but what also increases is the windage within the block and with that would also come an increase in vacuum from the potential 'venturi effect' which is exactly how the turbo oil returns work.

This is also exactly how the stock re-circ system works. you increase RPM hence windage and simultaneously the intake air speeds are increased which pulls more vacuum, a perfect cycle.

This is the entire reason why we have no clear answer to this debate, it can be used as a drain or vent on EITHER side of the block depending on it's location relative to the cranks centre.

Fact remains if you added a drain it would help oil problems and if you added a vent it would help oil problems, which way is best is what we will not know without testing (or copying the fastest R34 around a track M speed pics ppl????)

To add to your image 'conclusion' i have attached a link (posted earlier. the link is to the following product:

http://www.rhdjapan.com/jdm-low/Auto-Staff-RB-Engine-Oil-Return-Block-RB25DET-RB26DETT-59928

That is the exact drain used on the image you think clears everything up. They state:

Auto Staff RB Engine Oil Return Block RB25DET RB26DETT

You are viewing a Brand New RB Engine Oil Return Block from racing parts developer, Auto Staff.

This item will help relieve oil from accumulating in the head during hard driving by returning this oil back to the oil pan. This results in a smoother flow of oil throughout the engine and is recommended as a great preventative maintenance item.

Compatible Engine Model(s):

-RB26DETT Engine

-RB25DET Engine

They do not list where it should be attached to the block so it does not help with any part of this discussion but it seems clear on there 'intended' use. weather or not m speed followed this path we don't know. m speed pics

We do know they have it attached to the right side, which proves not much.

PS i am not taking any side. there is arguments from both setups. I do know that if a vent was the primary goal with no additional oil drain needed, a vent directly from the block would be far more efficient.

Maybe the m speed r34 team aim for both as even if it was located as a vent due to the size of the hose any reasonable amount of oil would have no trouble flowing down half the tube whilst the other half was still being used as a vent...

Despite what some think crank 'windage' is not all that strong. the main concern is pressure build up.

Edited July 5, 2009 by GT-RZ

[GT-RZ]

On another note there seems to be no small adjustable pneumatic 'mechanical' valves i can find.

I have a few places to ring around but for the most part i think the standard PCV valves may be the best option. cheap and easy to find, plus i noticed there is a few fittings for the later model nissans that don't have a thread machined on one side just a hose attachment each side which would be perfect!!