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Turbo drain back line size

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GNDriven

Active Member
Joined
Dec 9, 2004
Messages
648
I am hooking up my ball bearing turbo, its a COMP76. It has a very tight fit from the compressor housing to the T4 flange. I had to fabricate a drain back fitting to get me from the oil output port past the T4 flange. It narrows down to somewhere between 3/8 ID and 5/8 ID. I know most run a -10 return line, so I am really concerned that the oil will not flow out quick enough and be cooked inside the bearing housing.

This turbo has a internal oil restriction on the input like most BBs turbos, so I am thinking if less goes in then maybe less will need to go out.

Also, I just can't imagine why it would need a -10 for the return. I know the oil return is mostly gravity, and you want as low as pressure on the return, but I still can't reason it.
 
I wouldnt risk running a line with that small of an i.d. You should consider relocating the drain.
 
We have used a -8 AN drain line on many BB turbos with no issues for years.
 
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