exactly, and when you put a CASE of oil in when you change oil, there's all sorts of backpressure being built up. it's very significant.

Gack! You guys!

The seals/bearings don't fail from the oil flow. They fair from the oscillation from the high flow.
Try an experiment:

Take the open end of a garden hose and point it up. Now, kink the hose about 6" down from the outlet. and turn on the water. If you kink it right, you can stop the flow entirely.
Now, put a pencil in the hose and gently let the kink out enough to get just a burble of water coming out. The pencil will pretty much just float in the stream.
Now, let the kink go, but hold the pencil in with your finger. Do you feel what the pencil is doing? Now, let go. Where does the pencil go?
That is the shaft floating in oil inside the sleeve bearing. If you force a ton of oil past it, it has to flop around a lot as oil tries to make it by on one side or the other. This causes contact and distortion of the seal.

So, we not only need to be suffciently stupid enough to run too much oil through the turbo, but we need to be additionally stupid enough to over-fill the motor?

That would ONLY be if you put in oil faster than it can get out, and this is what we are talking about stopping with a restrictor.

In reality, the turbo doesn't care where the oil comes from. If you were able to get the return to back up just to the point that oil stops at the turbo, the bearings would wick up enough oil to be happly with zero flow.
Unfortunately, that oil will get real hot, real quick.

If you are getting a backup with the turbo above the level in the pan, you are swamping the return line and that is simply way too uch oil.

By reducing the tube diameter you are increasing pressure. The oil will flow faster and harder hence more pressure at the seals.

Isn't that what you wanted to prevent in the beginning.

Maybe it helps smoking at idle, but the return line and location is more of a signifigant problem.

Put a nozzel on your garden hose. Squeeze it. Notice how it sprays. Now squeeze it fully.

No more spray but a steady hard stream. The volume of water is the same but the pressure increased.

Ok,let me get this right. Too much oil into the turbo to the point where it can't drain fast enough is bad. Resticting the oil going in the turbo will result in less oil, but more pressure. How about increasing the flow out of the turbo? I want a turbo, so i'm trying to learn the most that I can.

The difference between your analogy and this situation is that here we have a constant pressure behind the restrictor. So, I think the pressure in front of the resitrictor should be proportional to flow rate.

We aren't reducing the tube diameter, only placing a restriction in it. The diameter of the hose is larger behind the restriction.

Fortunately, that is completely wrong.

It already empties above the oil level.
Even if you wanted more slope, you can't get it without moving the turbo which means a new manifold.

The oil will "condense" just fine in the space alotted, provided the flow is kept down.
Gravity is the mitigating factor. Simply providing an additional area will, in effect, simply expand the oil pan. Fluid will always find its own level.
The oil level is about 3/4 of an inch higher than the mating surface of the oil pan to the block.
The turbo oil outlet sits above that by more than an inch and the bearing another 1.5 inches above that (which is the point the oil would have to back up to in order to be an issue).
I suppose in a persistent left turn above .6g or so the oil would "slosh" enough to be a problem, but who drives a turbo RX-8 in the NASCAR circuit?

This is all a moot point, IMHO. When I ran my flow rate tests, the oil coming out was not frothed at all. Of course, this was at idle, but I'm not sure how it would get all frothy going through the turbo anyway.

MD

Can someone with a mathmatical understanding of flow rates vs. PSI chime in here?

For fluid flowing through a pipe it is analogous to Ohm's law (V=IR) where pressure is analogous to voltage, flow rate is analogous to current, and resistance is a function of pipe diameter, fluid density and viscosity, and flow conditions (laminar/turbulent).

Pressure and flow rate are generally directly proportional,

Through a pipe yes, but through a nozzle, such as the restrictor, the relationship is Delta flow =sqrt(delta pressure). So 4X the pressure only gets you 2X the flow.

Why can't the pipe itself be considered a long nozzle? Shouldn't the 4x pressure = 2x flow apply to the pipe as well?
________
Lovely Wendie99

No, assuming laminar flow, the flow rate in a pipe is directly proportional to pressure, assuming everything else is constant.

because the nozzle has a discontiuity in area. The pipe doesn't.

From my fluids book, the pressure drop (assuming the area has been reduced by 4x due to the restrictor) should be ~2x, ignoring the head loss on the front side of the restrictor.

anyone have any pics of what it looks like?

so if i wanted to do this, what part do i need to buy, and where would the restrictor go? just before the pan? Into the pan? I will be buying the greddy upgraded oil pan shortly..

I googled .065" restrictors and got nothing. I did find this though:
http://www.atpturbo.com/Merchant2/me...egory_Code=OIL


I did find some other people who mention this problem and are also adding restrictors:
http://www.dsmtuners.com/forums/showthread.php?t=171317

No. Not the pan... You're trying to save the turbo, not the pan.

It has to go between the pressure source and the turbo, i.e. between the engine block and the turbo.

BTW: I did that nitrous nozzle trick, too. Except on my setup, I dremmeled the cone off the nitrous nozzle, not the ftting. Its easier that way. Plus, if you use a brass nozzle, it forms a kind of compression washer and seals things off nicely.

You can just have the oil fitting on top of the turbo welded shut and then drilled out again with a 1/16" drill bit.
That is, in a nutshell, all I did.

well yes volume of the oil u got goin in n out is in corrlation to the flow u have x the pressure its exerting...... now if ur complainin that the turbos r smokin becuz of too much oil, n u put an extra restriction in there such as a nozzle....... lets use this analogy would be like ok u have a garden hose at ur house hooked up to the wall.........u have the spicket at the wall, lets say is the turbo........ n the spout or gun whatever u use...... is the oil pan........ now to use a nozzle as u do with the return line........ is like takin a clamp......n puttin it some where on the hose....which is cool when u dont have much water goin through (IDLE), but when u turn up the volume of water, (FLOW * PRESSURE), then that will start to back up....... n the back up gets bad enough, what happens to hoses when u have the water turned all the way up n the hose clamped down, no pressure to the Gun at the end, n water will back up through the pipes, or ull just basically make the hose explode lol.........now its too bad nobody can make a sort of oil pressure regulator........ u know how they have a fuel pressure regulator, but make this oil pressure regulator, work in reguards to rpm.........????? im sure RotaryGod, or Scott at Mazport with there all ready ingenious ideas for our RX8's could make cook up somethin in that reguards?????

^^ that is so hard to read, sorry for being picky.

So from what I can gather with pictures and stuff, there are 2 problems.

Too much flow.

Oil return is below the oil level.

Seems like a compound issue. So if we restrict the flow, it solves 1 issue, so how do you solve the return being below the oil level?

No, no and no.
Just put the 1/16" oil restrictor in and you're done. There needn't be any more science unless you are looking to write a thesis.

A thesis written like that would be even more incomprehensible than that horrendous post. Kind of hard to believe, eh?

Indeed. Kinda James Joyce-esque, actually.

is this a solution for the greddy turbo guys? And, where can we get a 1/16th oil restrictor from and I assume this fix is something you could do yourself?

alex

Its for ALL turbos. A turbocharger only needs a constant trickle of oil. If you are feeding it oil at full pressure and flow, you will chew up the bearings and blow the seals.

I made my own (welded the orifice of my aluminum oil fittng shut and then drilled it back out with a 1/16" drill bit). MadDog used a nitrous fogger nozzle restrictor.

This is the item provided to me by Scott of Mazsport... Similar to the one Maddog is using

https://www.rx8club.com/attachment.p...id=84157&stc=1