best way to tap oil return without removing oil pan

[IvoryJ30t]

why do you people think having the return submerged is going to cause this huge restriction?

[C-Kwik]

i know it comes out of the turbo as a foamy froth, but the pressure of the incoming oil is more than enough to over come the weight of the two inches or so of oil the return tap is submerged in.

if the addition of 0.1 psi of pressure to the bearing housing is enough to blow the seals, you have a problem.

That's the point. There is no pressure after the turbo bearings. The oil hits the bearings under some light pressure. But afterwards, it's strictly up to gravity to pull the oil away. This is the same reason you shouldn't have the oils passages more than 30 degrees from vertical in any direction. So gravity can have the greates effect on the oil. Under cruising, you'll probably never notice a problem. Do some road racing for an extended period and it will definitely fill up the drain line with enough froth to restrict oil flow from the bearing. The oil will have no place to go but into the turbine.

[IvoryJ30t]

yeah, but if the oil is entering the bearing housing under pressure, the pressure isnt just lost to atmosphere, or the oil would spray all over the place. im just saying that i very much doubt that the oil would not drain. there is definately enough pressure created by the oil supply to drain the housing.

[IvoryJ30t]

even if the oil supply was 5 psi it would still be enough to drain into the pan.

[C-Kwik]

Here's the thing, turbo bearings aren't fully bathed in oil. It's the point at which they are that it starts to leak past the seals. So by the time the oil passes through the bearing, it has effectively 0 pressure. So the ONLY force that removes the oil from the bearing housing is gravity. If there is any restriction to this, the bearing will become bathed in oil and leak past the seals.

While it is possible to build a reliable system with the oil return feeding under the oil level line, I would advise against it. One, for the reasons stated above. Two, when oil is frothy like when it leaves the turbo bearing, it's better to let it float on the top of the oil in the pan until it returns to a more normal state. The frothy oil likes to float. A drain line that enters below the oil level will have oil in it as high as the oil level itself. The froth will have very little surface area to dissapate in. There are certainly a lot of factors that need to be considered, but if I'm building a system, I'd refrain from accepting compromises when I don't need to.

[MikeMurphy]

interesting thread.