2mm is what should be used.
Flow is more important than pressure.
According to whom? (In reference to the 2mm statement)
2mm orifice for Ball Bearing?
My new turbos (Borg Warner K27.2 over K16 on a 4bt.) are leaking oil past the shaft seals after about an hour of runtime, so I researched as best as possible.....
I called around recently for info on this topic.....
Called:
- the local Injection/Turbo shop (Metro Fuel Injection, Allentown, pa)
- Blouch Turbo
Both stated journal bearing turbos are fine at engine oil pressure with no restrictor....FWIW
Consensus was that you cant over oil a journal turbo, but you can easily under drain it.
I have I believe -6 feeds on both chargers with two -10 drains feeding to a t onto a single -14 to the pan. I believe the "T is causing oil to back up past shaft seals......
From turbonetics website
"The turbocharger seals located at the compressor and turbine ends of the turbocharger have a primary purpose to keep pressurized air/exhaust gases from entering the turbocharger and then the crankcase. The fact that they also help control oil from entering the compressor and turbine housings is secondary. The oil entering the turbocharger is pressure fed from the engine but relies on gravity to return it back to the engine. Any restrictions in the oil drain will cause the oil to backup inside the turbocharger and be forced past the seals so it’s very important the oil returning from the turbocharger to the engine is free flowing with no restrictions. It is also important that the oil enters the crankcase above the oil level. Oil leakage from the turbocharger seals can be caused from and number of conditions, below are the most common. 1.Excess engine cranks case pressure A.due to poor crankcase ventilation like a plugged or improperly working PCV (positive crankcase ventilation) system or an open port from the intake manifold to the crankcase. B.Excessive engine blow by due to worn engine components 2.Too small of an oil return line, preferably ¾” to 1” minimum inside diameter 3.Oil return line routing is critical, there can be no sinks/traps and oil must return above the oil level in the crankcase. 4.Blocked oil drain at turbocharger or crankcase caused by incorrectly installed oil drain gasket or excessive use of silicone gasket material protruding into the oil drain flow path. 5.Air filter restrictions (too small or dirty) will cause a restriction and contibutesto excessive amount of vacuum on the compressor end seal causing oil to be drawn past the seals."
Unrelated but related......Drains are almost more important than feeds. It seems easier to puke oil being under-drained than overfed on a turbo.....
