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Can i run my oil return for turbo to a valve cover?
Im setting up a single turbo forged ls1. Its a precision 67 turbo. The oil feed is tapped in above the oil filter housing. I bought the kit used a the previous owner said the return would need to be tapped into another part of the oil pan.
I had an idea, if its a return why not just run a line up to the pass valve cover where i have the pcv port blocked anyway and return oil into the valve cover. That way there is no more drilling the block.
If this has already been done a million times, sorry im new in the FI game. If there would be any problems please let me know.
Gotta go to the pan unless your entire turbo is higher than your engine. If the return is under enough pressure to push it back up to your valve cover that will be enough pressure to push oil past your turbo seals. If you don't you risk taking the oil seals out of your turbo. Oil will go past the seals and you will smoke something terrible. I've seen others make this mistake. Take the pan off and drill and tap it now, way easier than after you have it all in the car and realize that's what you need to do. Best advice you'll ever get on this one.
The oil coming out of the turbo if its got bearings, is foam at first, the return line should be as large as possible and as steep as possible for as long as possible. Any back-pressure on the return is going to back oil up against the seals and reduce their life.
YMMV, this is just my experience road racing them. May not be as critical if you not doing long sessions like we did.
The turbo is not pressurized with oil. There is a restrictor with a very small hole that only allows a small dribble of oil into the center housing simply to lubricate, it's not like a crankshaft bearing that's designed to hold loads. Turbos are not sealed units. If you were to run a return line higher than the turbo - or even level to the turbo - the oil wouldn't return at all, it would go into your exhaust and intake. That's why not only is the line supposed to run as straight down as possible, it also needs to be MUCH larger than the feed line because gravity is doing the work, not oil pressure, and there needs to be as little amount of resistance as possible for it to drain.
Ok i will weld on a fitting to the pan , As far as the fitting is a 10an to 1/2 npt good enough or a 10an to 3/4 npt better .. what fitting are you guys running?
IIRC the 80 Trans Am I had that had the 301 Turbo had the return run into the VC... Maybe it was the valley... Had one back in 93-94 so it's been a while. I did a 400 Pont. With a turbo so my familiarity with the factory set-up was the day it took me to rip it all out. I know the early Non-IC Buicks just ran them to the valley, had a couple of those as well.
I need to change where I'm putting my return do to the crossover pipe being in the way , can I put the return I the front of the oil pan where I'm pointing ?
I'm running a low mount Huron Speed V1 AC kit and have my turbo drain line entering the pan right above the drain plug.
The drain line is almost flat but doesn't smoke unless I'm on the brakes hard down an incline, like say down a freeway off ramp from 100+ mph lol.
Even then its a small amount of smoke for a few seconds.
I also attribute it to working as well as it does because I use a MM PCV catch can.
Due to the kit design placing in the timing cover or pan front wouldn't and fortunately this has worked out very well.
08-21-2007, 11:45 PM
Can i run my oil return for turbo to a valve cover? 
