What is the correct size oil feed line for a T3/T4 bolt-on turbo?

MarkIII4Me

Project OVERKILL!!!
Apr 10, 2005
1,249
2
38
Charleston, SC
I just started running a Turbonetics HiFi 62-1 journal bearing bolt-on turbo which starts smoking as soon as my oil pressure starts to peak at the higher rpm's. But doesn't at lower rpm's. SupraSport sent me a pre-fabbed line kit. The feed line has around a -6AN line with 4-AN fittings crimped on the ends. Both the turbo and block have -4AN fittings installed. Would this be causing excess oil pressure to push through the seals? I know -6ANthat is too large, but don't the -4AN fitting produce the same restriction as running a -4AN line?

I was told told that simply reducing the fitting at the turbo with an adapter will not work and the the entire line will need to be smaller. Not sure why, since a I have heard of reducers being used in many setups, which would do the same thing.

What is the correct size feed line to use? I've read that if I go -3AN I will not need a reducer. I have also read to use a 0.60 reducer at the end of the line.

Currently oil leaks from both the front amd rear seals. The oil return line is -12AN at the correct angle with no kinks in it.

Any info provided will be greatly appreciated.
 

IBoughtASupra

New Member
Mar 10, 2009
4,455
0
0
Queens, NY
E-Mail Turbonectics and ask them what should be used for your turbo model. .060 reducer is common with ball bearing turbos and I have seen them on a Greddy T3 BUT it does vary depending on the manufacture.