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Old 05-22-2008, 06:37 PM   #1
manxaru
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Default turbo oil return line - OK to add oil cooler?

I'm looking at adding an external engine oil cooler to my 2.5 sti motor build. To get the most heat transfer out of the oil it makes sense to try and pick up the oil at it's hottest point. One potential pick-up point would be the turbo oil return line. It's a physically convenient spot and it seems the oil would be pretty hot after leaving the turbo.....BUT

I remember reading somewhere that the turbo oil line should return directly to the oil pan. Can anyone verify if this is correct? What is the reasoning? Would it not be OK to add an oil cooler after the turbo?

If that is true, where would the next highest temperature oil be found? Picking it up somewhere in the block or from the heads?

Thanks!
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Old 05-22-2008, 06:58 PM   #2
St.race
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You just have no idea how things are working! If you need to run an oil cooler, buy a kit and let your tuner shop install it for you.
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Old 05-22-2008, 07:08 PM   #3
manxaru
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Quote:
Originally Posted by St.race View Post
You just have no idea how things are working!
Please explain. Are you disagreeing that a higher delta T between the oil temperature and air temperature (moving over the heat exchanger) will result in a higher net heat transfer?
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Old 05-22-2008, 07:23 PM   #4
St.race
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You missing a point. I hope someone will be able to explain to you more.
1 You need a pressure so that oil would go thru an oil cooler and not just stay there.
2 You need a volume
3 You need to understand that a you would be benefiting from a cooler oil ruining thru your engine not a oil pan.

Now I hope you would look thru oil distribution system.
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Old 05-22-2008, 08:22 PM   #5
manxaru
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Quote:
Originally Posted by St.race View Post
You missing a point. I hope someone will be able to explain to you more.
1 You need a pressure so that oil would go thru an oil cooler and not just stay there.
2 You need a volume
3 You need to understand that a you would be benefiting from a cooler oil ruining thru your engine not a oil pan.

Now I hope you would look thru oil distribution system.
Totally agree with 1 and 2, that is why I am asking the question. I can't fit a normal oil cooler adapter between my filter and block (due to a custom install) so where is another access point to get good oil pressure and flow for the cooler? You do elude to a valid point that the amount of oil running thru the turbo is probably too small to make a good pick-off point for the oil cooler.

I don't really agree with point 3.
Q. Where does the engine get oil? A. The oil pan.
So if you have cooler oil in the pan, you have cooler oil being pumped thru the engine.

Thanks.
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Old 05-22-2008, 08:52 PM   #6
Patrick Olsen
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Quote:
Originally Posted by manxaru View Post
Please explain. Are you disagreeing that a higher delta T between the oil temperature and air temperature (moving over the heat exchanger) will result in a higher net heat transfer?
Yes, a large delta T is good. But the oil from the turbo needs that direct drain path to be sure there's no restriction that might cause it to back up in the turbo. If your oil cooler causes too much of a restriction, you reduce flow thru the turbo bearings and BOOM!

Quote:
Originally Posted by St.race View Post
3 You need to understand that a you would be benefiting from a cooler oil ruining thru your engine not a oil pan.
Last I checked, the oil pump draws from the oil pan to send oil to the engine. So the difference between drawing cooled oil from the pan, or pumping hot oil thru a cooler to feed the engine would be negligible.

Pat Olsen
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Old 05-22-2008, 08:54 PM   #7
Patrick Olsen
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Quote:
Originally Posted by manxaru View Post
Totally agree with 1 and 2, that is why I am asking the question. I can't fit a normal oil cooler adapter between my filter and block (due to a custom install) so where is another access point to get good oil pressure and flow for the cooler?
Use a take-off plate and a remote-mounted oil filter. I think that's your only option.

Pat
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