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Turbo Scavenge Return Line to Valve Cover?

Has anyone with a 930 ever routed their scavenge return line to the valve cover?

If so, pros/cons.

I have a car with the oil tank mounted in the front trunk area, and I really don't want to run another line all the way up there, plus I'd have to modify the tank to accept another inlet, which I don't want to do.

I've seen 1 engine with the scavenge line routed back to the 1,2,3 lower valve cover. I'm just not sure where they machined the valve cover to weld on the fitting. Anyone know the best place to do that? Any pics?

Brian
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Old 02-25-2005, 06:01 PM
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Uhh...930 has scavenge pump from oil sump so you don't see that too often. Valve Cover trick is band-aid used by guys who turbo-cenverted their N/A engines and don't have scavenge-pump installed.

May I ask why you moved oil-tank to fron trunk?
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Old 02-26-2005, 01:50 AM
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I'm speaking of the turbo scavenge pump return line, that on a normal 930 would dump right back into the bottom of the oil tank.

My 930 is basically a race car. The tank in the front has a 24qt capacity.

So I wanted to dump the oil into the valve cover so that the oil pump would pick it up and route it back through the AN16 line that goes to the oil cooler in front, and eventually to the front tank.





Brian
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Old 02-26-2005, 04:14 AM
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If you dump the scavenge oil directly into the engine you will by-past the filter. Turbo chargers when shut down super heat the oil in the bearing cartridge and this oil can turn to chunks of material (coke) that you don't want in your engine.
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Old 02-26-2005, 06:43 AM
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Henry:

So I should just run it back to the front of the car?

I see your point.

Just trying to figure out the best way to tie it into the existing plumbing.

Brian
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Old 02-26-2005, 05:51 PM
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Hey Henry, if the cleanliness of the oil is the only primary concern with dumping it back into the valve cover, couldn't I place an inline oil filter between the scavenge pump outlet and the valve cover and just replace the element, or clean it after each track event. (I normally change the oil after each track event anyway).

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Old 02-27-2005, 04:19 AM
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Me dont think so cause you do not want preasure on the return end...all kinds of problems....unless you had a small pump pick it up (scavage) and run it thrue a filter
Old 02-27-2005, 09:11 AM
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afterburn:

Your post makes no sense.

Can you elaborate?

Brian
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Old 02-27-2005, 09:39 AM
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On my daily driver turbo 3.0 914 I am dumping it into the lower valve cover with out problems, I drilled and tapped for a pipe to AN 90 fitting. The top of the breather is another spot to consider Thats were Richard Clewett dumps his in his race car. But I would think the return to the oil tank is still the best.
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Old 02-28-2005, 03:10 PM
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there can be no preasure in the line after the turbo,that is why a filter there will not work.Now Harry is a smart guy and been around....but I will have to say there a gazillion expensive diesel engines (expensive too) that dump th oil strait back in the pan.
On the other hand Porsche runs thirs to a little sump in the rear of the engine and a scavage pump sucks it back to the tank.....so I have to think they know what they are doing too
Old 02-28-2005, 03:54 PM
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Why don't you just plumb it into the main scavenge line that is already connecting the engine pump to the tank?
Old 02-28-2005, 07:18 PM
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I figured the flow of the oil from the engine, would overpower the flow of oil from the turbo scavenge pump, and I figured the oil from the engine would try to flow up into the scavenge line, which would back up into the scavenge pump, pretty much reducing or eliminating the scavenge process.


That's just the way I looked at it...

Brian
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Old 03-01-2005, 05:17 AM
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In the normal 911 circuit, oil from the scavenger pump goes through the cooler and then through a filter before it is dumped into the oil tank. There is no filter between the stock oil tank and the pressure pump. Unless Brian's non-stock-relocated oil tank has changed the way the circuit works, dumping the oil into the case is not going to be a problem.

Where in the new circuit is the oil filter?

Edit: Are you not going to use the turbo sump-pump?

Last edited by MotoSook; 03-01-2005 at 06:31 AM..
Old 03-01-2005, 06:12 AM
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Brian smith is right.....to hook it to the return on the scavage side out side the eng. would in effect plumbing it back to a "preasure" side, cause that is under preasure going back to the tank.Rember the oil pump is two in one,one for oil p. to the eng. and the other to pick up and deliver back to the tank
Old 03-01-2005, 06:58 AM
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There shouldn't be much more than fluid head pressure in the scavenge to tank line assuming the line is not too small and there is not a filter in the circuit.
Old 03-01-2005, 02:44 PM
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Picture of valve cover oil dump connnection
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Old 03-01-2005, 02:51 PM
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