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Old 09-06-2006, 01:29 PM   #1
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Default Oil Drain Revelation and Fuel Pressure Gauge Setup

All right, this idea warrants it's own thread. First though, I found my local hydraulic/pipe/rubber supply shop and not a minute too soon. I walked in with my Begi FPR in hand... set it down on the counter... the guy looked at me and said,
"You gotta gauge yet?"
"Nope, that's what I'm..."
"Just give me a second," he said and disappeared into the parts isles.
He came back in a minute with the gauge and three brass fittings. $13.50 for all of it. Gotta love a pro. I guess it doesn't hurt to be around the corner from the local speed shop.

NOW, ON TO MY EPIPHANY!
So, I thought there had to be a better way to tap the oil pan... and started searching. I came across a turbo kit that included a fitting that just replaced the oil pan drain plug. BINGO! Check out the pic below... the bolt at the top is a stock oil drain plug. The brass fitting to the left is the same thread pattern with a barb that to fit a 3/8 oil drain line. The routing isn't that hard, just follow the dipstick down to the pan, around the bottom back of the pan and into the barb... or threaded fitting or whatever for braided lines.
The point is, why not just drain the turbo back into the drain. Is this feasible? Any drawbacks? The suction provided by the valve cover line into the intake should pull oil into the bottom of the pan the same as it would the side. I'm not against tapping the pan, w/no AC or PS, it should be easy... but maybe an idea for others. Check out the pics, whaddya think?
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Last edited by samnavy; 08-01-2007 at 10:37 PM.
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Old 09-06-2006, 01:42 PM   #2
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That gauge is nice, but it's not going to do you any good underneath your hood. You want to buy about 5 feet of fuel line so you can mount it on your windshield while tuning. After you car is tuned , you can remove this gauge.
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Old 09-06-2006, 01:50 PM   #3
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You can't drain the turbo into the pan's drain plug because that's below the level of the oil in the pan, making it impossible for anything to drain.
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Old 09-06-2006, 02:38 PM   #4
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Originally Posted by bripab007 View Post
You can't drain the turbo into the pan's drain plug because that's below the level of the oil in the pan, making it impossible for anything to drain.
I don't think that's entirely correct.

There will be some standing oil in the drain line, equal to the level of the standing oil in the pan. As the vehicle experiences lateral acceleration and the oil sloshes around the pan, the level of oil in the drain line will rise and fall. However as oil flows out of the turbo and goes down the line, it will displace some of the standing oil in the line out into the pan. The system will tend to maintain equilibrium.

I don't think this will hurt anything since the level of the standing oil will be far below the outlet of the turbo, and the quantity of oil going through the turbo is actually quite small- it wonít be coming out fast enough to accumulate any significant head above the ambient level in the pan. Itís not necessary for the drain line to be completely empty, just that it run more or less downhill and unrestricted so that gravity can do its job.

Imagine taking a glass of water, and holding a straw above it so that the bottom of the straw is not touching the surface of the water. As you pour water down the straw, it will flow out into the cup. This is our usual tap-the-pan-above-the-oil-level method.

Now, imagine lowering the straw so that an inch or two of the bottom is submerged in the water. You can still pour water into the straw, and it will still flow out into the cup. There is standing water in the straw, however it is never higher than the level of water in the cup since the pressure is equal on surface of the water and on the open end of the straw.

About the only downsides I can see here are having to pass the oil drain line close to the downpipe, and making an utter mess when itís oil change time.
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Old 09-06-2006, 02:44 PM   #5
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I tapped Newbsauce's pan on Monday. It's not hard I tell ya! I'll send you down my bit and tap and JB Weld!

Can you give me the source of that guage? I cant find anything here that goes above 100psi.
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Old 09-06-2006, 02:53 PM   #6
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Joe, I've never tried the straw and cup of water experiment, but I'm pretty sure the pressure of the volume of water (read: oil) in the cup (read: pan) will prevent the fluid from draining properly.

I just don't see any possible way fluid could drain into a downward-facing hole. It'd be interesting to see someone try...and post here the next day that their turbo is smoking and/or oil is spraying from the seals of the CHRA.
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Old 09-06-2006, 03:10 PM   #7
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Try it. All things being simple, Joe Perez is right. But I can see some ambient crankcase pressure preventing the oil from draining ideally. Yeah, you'd need a bunch of head pressure to fill up that entire drain line, but you never know until you try.
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Old 09-06-2006, 03:42 PM   #8
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Quote:
Originally Posted by Stripes View Post
That gauge is nice, but it's not going to do you any good underneath your hood. You want to buy about 5 feet of fuel line so you can mount it on your windshield while tuning. After you car is tuned , you can remove this gauge.
Crap, I figured the tuner would want it next to the unit so he could make adjustments while watching the gauge... and then it would just sit there forever and look cool. Goodie, another excuse to go back to the Pipe and Rubber Store (sounds kinky).

Quote:
You can't drain the turbo into the pan's drain plug because that's below the level of the oil in the pan, making it impossible for anything to drain.
I'm an arts major, but I thought a basic property of fluid dynamics was something about leveling. Since the drain out of the turbo itself is higher than the level of the top of the oil in the pan, it should drain just via gravity. But considering that the oil going into the turbo is under pressure, it should be pumping it through just like any other recirculating system. It should work fine. Now we gotta get somebody to try it. I'm gonna do the easy route and have somebody hold a air hose into the vavle cover while I drill very, very, very slowly, but some newb w/all that a/c p/s crap in the way might want a fresh approach.


Quote:
I tapped Newbsauce's pan on Monday. It's not hard I tell ya! I'll send you down my bit and tap and JB Weld!
Can you give me the source of that guage? I cant find anything here that goes above 100psi.
In a week or two, I'll take you up on that "bit and tap"... save me the cost of a one time tool. The Guage says Dixon on it... I found their website http://www.dixonvalve.com/ but couldn't locate which subsidiary company makes the gauge. I just looked in the Fairfax are yellowpages but couldn't see anything promising... I bet the guys at your local farm machinery store maybe a plumbing store would know.

Last edited by samnavy; 09-06-2006 at 04:02 PM.
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Old 09-06-2006, 04:28 PM   #9
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Originally Posted by samnavy View Post
but some newb w/all that a/c p/s crap in the way might want a fresh approach.
It's not in the way...Here's mine:



I've even routed my intercooler piping straight down next to the two units as well!
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Old 09-06-2006, 04:48 PM   #10
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I'm an arts major, but I thought a basic property of fluid dynamics was something about leveling. Since the drain out of the turbo itself is higher than the level of the top of the oil in the pan, it should drain just via gravity.
Nope, it won't work. Think about the volume of oil in the pan vs. the amount coming out of the turbo in the drain line...there's just not enough of a volume/pressure to push the oil into the pain if you're below the drain line. There's a reason that no turbo system in the world (unless it has an inline pump) dumps into the pan below the level of the oil in the pan. I'm still trying to think of an easy way to demonstrate this to you using household items.

Quote:
But considering that the oil going into the turbo is under pressure, it should be pumping it through just like any other recirculating system. It should work fine.
Nope. The turbo oil drain outlet is not under any sort of pressure; it only has gravity and any crankcase vacuum to help it drain. There's a reason (there always is!) that it's recommeneded to plumb the cam cover breather hose into the turbo inlet to build some vacuum in the crankcase and help drain oil from the turbocharger...and that's on a properly-plumbed, above-oil-leve-in-the-pan turbo drain setup! There's people that have turbo smoking (read: oil drainage) problems just from using a cam cover breather!

That being said, I challenge you to make it work. If you can somehow get it to work, you may have a market for something
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Old 09-06-2006, 05:01 PM   #11
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Quote:
Originally Posted by bripab007 View Post
There's a reason that no turbo system in the world (unless it has an inline pump) dumps into the pan below the level of the oil in the pan.
The OEM drain line on my cousin's Passat TDI drains below the oil level, if my memory serves me right. I remember looking at that and thinking "hmm that's strange, I thought that didn't work". I also don't remember seeing a pump, but I only looked at it for a few seconds as I was changing the oil.

I still wouldn't do it.
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Old 09-06-2006, 05:13 PM   #12
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I agree with Brian, I don't think it would work...and if it did, it couldn't be very effective. The oil leaving the turbo would have to push against the head of the oil in the oil pan. Not to mention, the surface tension between the oil in the line and the small ID of the line itself would work against gravity in trying to drain into the pan from the bottom. In a perfect world, everything should equilibriate, but I don't think it would in this case. Granted, if there was a pressure force behind the oil due to the oil pump, but still, wouldn't you rather have gravity helping whenever it could? Its seriously not an issue to drill/tap a hole in the pan for a fitting. Then you have no surface tension effects, no head pressure to overcome, and gravity is helping get the hot oil away from the turbo.
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Old 09-06-2006, 05:28 PM   #13
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The OEM drain line on my cousin's Passat TDI drains below the oil level, if my memory serves me right.
Hmmm...interesting, but perhaps you didn't realize how tall the sump was or something; it can be misleading. Look at this cross-sectional of VW's 2.0T FSI engine, for example. At first blush, the oil return seems fairly low, but there's probably 4-5 inches of sump below the drain line (you might be forcing me to crawl under the Jetta when I get home from work today to take a closer look/measurement ).

Also, someone please explain how the oil drain plug return would work, given this drawing.
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Old 09-06-2006, 05:35 PM   #14
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Granted, if there was a pressure force behind the oil due to the oil pump, but still, wouldn't you rather have gravity helping whenever it could? Its seriously not an issue to drill/tap a hole in the pan for a fitting. Then you have no surface tension effects, no head pressure to overcome, and gravity is helping get the hot oil away from the turbo.
Maybe this is were some are not understanding how a turbo drains oil. Gravity is the only thing draining the oil out of the turbo; do not think that the turbo "pumps" oil through it just because it's being fed in at pressure. This is why most people experience improved drainage with a properly set up crankcase vacuum: gravity alone doesn't always even do the trick.

Oil coming out of the turbo is just a trickle of fluid that's not under any sort of real pressure. It'd be no match for a quart or two of pooled oil in the sump.
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Old 09-06-2006, 05:52 PM   #15
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I'm bored im going to try this straw thing with a stryofoam cup
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Old 09-06-2006, 05:56 PM   #16
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Ok, so all it does is fill the straw level to the water in the cup, which is what I thought would happen. Just like in a catch can, the tube on the side is an indicator of the level of oil in the can.

I really would want oil building up into the return line like that. Cause chances are it's going to backup straight into you bearing housing and say hi.
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Old 09-06-2006, 06:16 PM   #17
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I'd think the real saviour in this set is the oil pump pulling oil from the pan. In this case the drain tube is more like an extension of the sump itself- just providing a source of oil for the pickup. It gets removed from the tube by default, since it's connected to the sump. - rob
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Old 09-06-2006, 06:45 PM   #18
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Originally Posted by bripab007 View Post
That being said, I challenge you to make it work. If you can somehow get it to work, you may have a market for something
F-that... I'm not doing it after this discussion, I'm just the visionary who thought it up. I'm gonna tap the pan Braineak-style and use a whole tube of JB weld on it. Get Rican to try it, he'll try anything.
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Old 09-06-2006, 07:38 PM   #19
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OK, here is the story, as I understand it, with using the drain plug for a turbo oil return.

Normaly, if you think of the oil as a liquid, it would never go above the level of the oil in the pan. The problem is that you don't nessesarily have a liquid, what drains out of the turbo is a sort of oil/air emulsion. A frothy milkshake like mess, thats why the tube has to be so large. It doesn't flow down cleanly.

If you drain above the level of the oil in the pan the bubbles have plenty of room to dispurse over the top of the oil in the pan, so the turbo can drain well. Put the drain tube below the oil leval and the dispursal area is only equal to the area of the drain tube. So the froth can back up and cause problems in the turbo.

That is not to say that you can never attach the drain tube below the oil leval, just that it is harder to get it to work. For a DIY/aftermarket set up its just safer to have the drain tube go in above the oil level.
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Old 09-06-2006, 07:58 PM   #20
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hmmmm...ummmm ok
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