Precision Turbo and Engine Turbocharger Installation Recommendations - Manual (Page 4)

2.
Turbocharger oil feed line sizes. (BALL BEARING) The oil feed to ball
bearing turbochargers may be restricted but may not always be necessary. If a ball
bearing turbocharger is supplied with an oil feed restrictor fitting it is suggested
that this fitting be utilized.
All single ball bearing turbocharger applications should utilize -4AN or 1/4
inch inside diameter oil feed line.
All twin ball bearing turbocharger applications should utilize a -6AN or 3/8
inch inside diameter main oil feed line into a Y block to -4AN or 1/4 inch
inside diameter turbocharger oil feed lines. The -4AN turbocharger oil feed
lines from the Y block to the turbochargers should be equal in length.
TURBOCHARGER LUBRICANT RETURN LINE
The oil return is probably the most over looked item in a turbocharger installation. It is
the primary reason why a turbocharger will leak oil and smoke. The oil return is crucial
to a proper turbocharger installation.
1.
It is best that the turbocharger is mounted as high as possible so the oil will
gravity returns back to the engine. If returning the oil back to the oil pan the oil
return line fitting must be installed above the oil level in the oil pan.
2.
The minimum recommended oil return line size is -10AN or 5/8 inch inside
diameter. The fittings utilized should be of a free flowing design. It is also advised
sharp turns and tight radius fittings be kept to a minimum.
3.
On installations where the turbocharger is mounted low and an oil return pump is
utilized it is best if the pump is mount lower than the oil drain on the turbocharger
so that the oil drain will gravity feed the pump. Turbocharger oil return pump
system can become very complex and must be designed properly to function. The
proper size lines, reservoir, time delay relay, electric or mechanical pumps are
crucial to a properly functioning oil return system.
TURBOCHARGER COOLANT LINES
If a turbocharger has locations on the bearing housing for coolant lines coolant must be
run through the turbocharger. If coolant is not run through the turbocharger it will fail due
to excessive heat.