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Wow maybe I have a compression problem. I read it and its still used to drain oil. Or a method of managing blow by. But all my stuff is on the turbo side no fittings are on the intake side. I feel there is no evidence that one side is better than the other. It like saying I took a leek on the back side of a tree. There is no back side. A circle is a circle. Right after the center line it becomes equal again. So I might be wrong here but thats my 2 cents.

I understand that, but its still a circle. The vacuum can be created right after it passes the center line. And to me that a equal effect after all all the engineers at nissan couldnt get it all that wrong. So the a 2jz is was better not cause of 500cc more but because they placed the oil return on the opposite side. I feel the oil return based on side is just hype. The method in getting the motor to breath and manage blow by as well as oil drain is like 95% more valid than what side on the sump should be chosen. Thats all im saying.

Wow maybe I have a compression problem. I read it and its still used to drain oil. Or a method of managing blow by. But all my stuff is on the turbo side no fittings are on the intake side. I feel there is no evidence that one side is better than the other. It like saying I took a leek on the back side of a tree. There is no back side. A circle is a circle. Right after the center line it becomes equal again. So I might be wrong here but thats my 2 cents.

You are wrong but no point repeating all the arguments that are pretty much resolved later in the thread.

Wow that was weak. But its not an argument mate. Its just a discussion. A friend of mines from collage has a software witj liquid dynamics and he does some really good stuff with it. Ill see if I can have him do somtjing to show you my piont. As for reiterating. Things on threads thats a given. Cause from reading this tread which on of the best ive read so far. There is more if I may say off topic discussion around really good points. For exsample way back from page 16 and down someone menstion venting the sump. The difference is he didnt go into details people said no its a supply problem. But as I read on some people just changed the idea and place the vent line in the catch tank and change up the wording just a bit. Here what ill do all the same and use the opposite side for a comparison sake. I appreciate all advise on here. When I help people on here I dont have any problem saying things over agian. I just clean it up better the second time around.

Marcus,

I do CFD (that software stuff that your college mate uses for fluid dynamics modelling). Well, I don't actually do it - I have CFD people to actually do it, but that's not the point. The point is that doing a proper CFD simulation to show that one side of a sump is better than the other for venting, or to demonstrate that there is no difference, is not actually a trivial task. 90% of people who attempt it would do it wrongly. They would make the wrong assumptions going in, and they would interpret the results wrongly too.

Regardless, there is a better side of the sump to vent from, and it is because of crank rotation, and it is because of windage, and it is because the crank flings oil droplets more to one side than the other. And those are all different ways of saying the same thing. And you don't want the oil droplets in the sump gas that you vent, if you can avoid it.

Really, how does the crank spit oil more on one side then the other ?

Does it stop oil from getting pushed out on one side but then lets it go on the other :/

What alot of people dont take into account is the fact the crank case is under pressure at full noise where oil control or more venting control is most needed

Marcus,

I do CFD (that software stuff that your college mate uses for fluid dynamics modelling). Well, I don't actually do it - I have CFD people to actually do it, but that's not the point. The point is that doing a proper CFD simulation to show that one side of a sump is better than the other for venting, or to demonstrate that there is no difference, is not actually a trivial task. 90% of people who attempt it would do it wrongly. They would make the wrong assumptions going in, and they would interpret the results wrongly too.

Regardless, there is a better side of the sump to vent from, and it is because of crank rotation, and it is because of windage, and it is because the crank flings oil droplets more to one side than the other. And those are all different ways of saying the same thing. And you don't want the oil droplets in the sump gas that you vent, if you can avoid it.

Man. I was and will brake it down. Because all the oil is at the bottom in the sump. Chances are the coming around the crank will hit some oil and splash the oil to the intake side and just as it passes the center line, and that where ever you plan to place your an fitting. Then it becomes a vacuum. On the back end of the crank. Not that it spit it out or sucks it in. All im saying it that its totally even on eather side. Its simple. This reminds me of a f1 engineers can look at an engine block and tell how the layout internally is placed. This gift is priceless. Hence the 6 figure pay cheque. Look. If the carnk is in a 360 degree situation and most of the oil is in the bottom how can the crank coming up from the oil source before the center line not bring oil with the rotation (wet setup here) and after pacing the center line which is 90 degrees in most occasions only after that is there a vacuum. Only after that point of where you place your oil vent or an fitting. Just my two cents mate. But my friend is very very skilled at it but we haven't talked in years but went to school together. His pay has separated use over time. I have sent him an email. I invited him to the bahamas. Im sure if he comes this conversation wouldn't even matter. I just would be happy to have seen him again. But his skill I wouldn't even question in liquid dynamics. Not for one second. This is a great thread guys. Reminds me of why I like this form so much

Edited by MJTru
  • 2 weeks later...

update

from my build/thrashing thread

so have been doing some investigation into my catch can setup following eastern creek happy fun times

on long left hander’s i noticed that oil pressure would drop to 30psi under high load

i can confirm this with the Haltech data logger, plus warning lights and i was going so slow i have time to check guages mid corner at 180km/h

This has only cropped up since going to the hancock rubber ( never had a issue on the r888 which are slower)

so i checked my oil levels as i do and she was at the hump in the dipstick so 10 litres of oil in the slightly larger stock sump

so slapped another 2L in which brought the oil level up to crank level and about 1 inch above the kink in the dipstick (about 3 inches higher than the full line)

next session this resulted in perfect oil pressure on left handers however the downside was the catch can pumping about 1 litre of oil out the drain and under the car

i already had a cunning plan to fix this and was expected considering the thrashing teh car cops/ engine wear

i will be going to version 3 catch can which involves putting it the one way valve to the catch can and activating the external pump that i had installed (have not been using it till required)

i am hoping this will give me a extra year or two of thrashing ( or about 10 gearboxes time) before i have to start backing off the revs to control blowby

will also extend the -20 drain hose to back behind the rear cradle to that the poor bastard behind me cops it and not the under part of my car

It looks like the sump breathers are just pumping the excess oil up to the can and back through the top breathers. You need to be able to raise the breathers up some more by welding a tube bending upward like a little snorkel. Not sure if there would be room to do it though.

Is that breather off the filler cap really dumping to ground?

Hmm. Intresting. This oil issue is still hunting people out there. I have found oil control in the motor itself works with all the additional mods mentioned. I do drag racing and never put the car through a circuit racing. Im doing an experiment right now on a rb25. Im not thinking about this no more. Ive scrap up all my old parts greddy oil pumps that are still good and all different size resistors. Along wit some off the wall things like machining the block head and add a vent hole higher in this old block as high as I can go. We will see what happens. Hopfully I dont crash cause I have no circuits here. Im sick of hearing that skylines have this problem. :angry:

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