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Engine Specific Info and Questions => IDI Engine => Topic started by: haybayian on March 06, 2008, 05:19:12 am
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Since the lubrication question is being discussed now the time may be right to ask my own question. I am in the process of puting together a lubrication system for the turbo completely separate from the engine oil. i.e. a small oil can, a 12 volt oil pump, a pressure switch/warning light.
My main motivation (after a bit of soul searching) is to protect the turbo which I think is not adequately lubricated for high performance in stock engines. I know, I know, many of you may disagree with this statement, but I have my reasons for doing this.
Now my question to you is: in this independent oiling system of mine what would be the most suitable oil?
Thanks.
Haybayian
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#1, I'd use a synthetic oil. I probably would use the same weight as what your engine uses although you probably don't have to use a diesel specific oil since it won't be getting much if any soot.
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I agree with Jim, a synthetic oil will stand up to the heat better than a conventional.
My only concern would be, in a small self contained system with a 12 volt pump, I would think think the pressure would be fairly high compared to the system in your motor, I don't know if that would have any ill affects on the turbo.
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I'm sure you could restrict the flow enough for that to be a non issue. Don't forget that you can see upwards of 80 psi oil pressure with a cold engine. I think the system would work well but I believe you will still want to have a thermostatically controlled cooler for it. A closed system will have no way of dissipating all of that heat. :)
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also, oil from the turbo gets cooled in the engine (just from mixing with cooler engine lube oil), it wont in your system, so you'll need to find a way to cool it i think.
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also, oil from the turbo gets cooled in the engine (just from mixing with cooler engine lube oil), it wont in your system, so you'll need to find a way to cool it i think.
I agree with your points. Yes a small air oil cooler will be necessary to provide this separate lubricating system with a means to cool down. I am looking for one. Thanks.
Haybayian
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You really have to ask yourself if this level of complexity is really justified. What are your reasons for going to this level of complexity?
Have hi-po diesels been loosing turbos at a great rate? - No
Is complex better than simple? - No
Is an electric pump better than an engine driven one? - No
Is there anything wrong with the VW engine's oil feed to the turbo? - No
Then, why do it ?
As your signature says "Keep it simple if you can." :wink:
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+1 to what stewardc said.
Now that's out of the way I'd look hard at the lube supplied with the centrifigal superchargers (i.e. ATI Procharger, Paxton NOVI). They often use a lube that is self-contained. I think they have a higher shear-strength spec due to the gears, but otherwise the application seems similar.
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you also gotta consider the oil going to the turbo comes right off the filter housing so it's contaminant free, and cooler than the oil in the pan because it uses the oil cooler, it's a cool idea, but not one I'd personally implement considering the factory way is pretty darn good.
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You really have to ask yourself if this level of complexity is really justified. What are your reasons for going to this level of complexity?
Have hi-po diesels been loosing turbos at a great rate? - No
Is complex better than simple? - No
Is an electric pump better than an engine driven one? - No
Is there anything wrong with the VW engine's oil feed to the turbo? - No
Then, why do it ?
As your signature says "Keep it simple if you can." :wink:
As stated in my post I understand that others may not agree with what I am doing and this is fine.
The idea that turbo oil starvation is a common (potential)problem shared by most turbos was submited to me by a friend who is a mechanical engineer working at the national Research Council (Ottawa). What he suggested can be summed up as follows:
"Turbo Cool Down
A turbocharger is cooled by engine oil, and in many cases, engine coolant as well. Turbo's get very hot when making boost, when you shut the engine down the oil and coolant stop flowing. If you shut the engine down when the turbo is hot, the oil can burn and build up in the unit (known as "coking") and eventually cause it to leak oil (this is the most common turbocharger problem). It is a good idea to let the engine idle for at least 2 minutes after any time you ran under boost. This will cool the turbo down and help prevent coking".
In investing my time and some money in modifying the Garrett T3 oil supply is to prevent coking, as well as providing a steady flow of cooling oil independent from the engine mechanical oil pump. In my system the turbo's bearings will be oiled properly before the engine starts and after the engine has stopped (when the turbo is still running). At this stage I am investigating the use of a type of oil (probably synthetic) more suitable to high speed bearing lubrication. Your opinion on this subject will be welcome. :wink:
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you also gotta consider the oil going to the turbo comes right off the filter housing so it's contaminant free, and cooler than the oil in the pan because it uses the oil cooler, it's a cool idea, but not one I'd personally implement considering the factory way is pretty darn good.
This too is a good point which I was considering. So a separate oil filter it will be. No sweat.
Thanks.
Haybayian
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Ahaaaaaa, so coking is the issue, not lubing. The cure has been around for years. It's called a turbo timer. I've even seen a timer built into an electronic boost control. It's certainly simpler than a system that's complex, VERY subject to failure and unnecessary.
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I'm interested to see your setup, and understand your logic, so I'm not interested in bashing ;)
On the coking topic, high end modern synthetic oils are pretty good at preventing this, hence the strict 502.00, 505.00 vw oil spec requirements in the newer turbocharged cars. I can tell you from personal experience that regular conventional oils are not good at handling high heat like synthetics.
I've personally changed 4 turbo's on 1.8t's in the last month and I've only ever changed 3 td or tdi turbo's due to outright failure from abuse / neglect. I know all the 1.8t's were neglected (wrong oil from quickee lube) but who wants to pay 60 bucks for the right oil right? I have not seen a major failure like this in a car I know was run with the right oil from day 1.
Also, vw has implemented coolant after run pumps in all their hot running motors to aid in quicker cool down so the driver doesn't have to idle after driving, perhaps this could help you? perhaps you could run a water cooled turbo and run a water circuit as well? that might get complicated though.
Another thing to consider, gassers run way hotter than diesels in stock form... I'm not sure you can make a direct comparison. I've glowed the turbo on a 1.8t passat just driving down the road, but I have to practically rally race a diesel to glow it.
I would have to think that the majority of turbo failure studies are based in big trucks and passenger gasoline cars as they are more abundant than passenger diesels. Can your researcher freind tell us what vehicles were studied in his research?
Just a couple more points to consider.. :wink:
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Thanks Myke for taking the time to give my project full deck consideration. I am appreciative of the fact that you must know a heck of a lot more than I do about turbos and I am listening.
Yes I will provide this forum with pictures and explanations as soon as the paint dries (I have fabed some of the components). So far the system is based on: a 12 volt pump from Summit Racing (# $179.00), a small oil cooler (#$49.00), an oil filter head and filter (#$20.00, temp switch, pressure switch (2 x 20.00$), oil lines and scrap metal approximately $30.00. It is not an expensive project and certainly not a complicated one.
I will ask my engineer friend for references. He was not (himself) doing this research however . He was speaking as if these points were common knowledge.
Haybayian.
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Why not run a oil/water core? Some garretts are dual cooled. My IHI 5RHB in my old Thunderbird TurboCoupe was that. Far simpler, just need to run a tap off the coolant line to and from the turbo.
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I think this is a great experiment... looking forward to the pictures. Would I go to all this particular extra effort in this one area myself... probably not. Gonna enjoy learning from someone else's experience ? Absolutely !!
The after-run cool down cycle is pretty standard as a way to deal with heat soak... given how self-contained you are building this system you could easily add a simple timer circuit to run your oil cooling system for a few minutes after you shut down the engine. Or close the loop completely and have the after-run cooling cycle temperature controlled ?? Sounds like you have an oil temperature sensor in place already ?
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I think this is a great experiment... looking forward to the pictures. Would I go to all this particular extra effort in this one area myself... probably not. Gonna enjoy learning from someone else's experience ? Absolutely !!
The after-run cool down cycle is pretty standard as a way to deal with heat soak... given how self-contained you are building this system you could easily add a simple timer circuit to run your oil cooling system for a few minutes after you shut down the engine. Or close the loop completely and have the after-run cooling cycle temperature controlled ?? Sounds like you have an oil temperature sensor in place already ?
Thanks Vincent for your supporting thoughts. Yes what I am doing is "experimenting". There may be other ways to achieve the same goal. An electric pre-lube (non continuous) pump plumbed to the engine oil piping somewhere is one I have read about. All I think my system provides over the former is the choice of a separate oil and cooler. It is also "non invasive". What I am doing is to disconnect the VW turbo oil supply line, plug it at the filter mount and set up the contraption that I was describing yesterday directly to the turbo. I don't expect my system to be perfect but rather that it will need to be fine tuned, modified etc.
Indeed I plan to wire a timer so that the turbo lubricating system will be running before the engine starts and after it has been shut down. I have not given this any attention yet .
Haybayian
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I'm interested to see your setup, and understand your logic, so I'm not interested in bashing ;)
As promised. Please find below a picture of the components of my turbo independent lubrication system.
From left to right:
1) a home built independent oil can. This is a steel box approximately 6" x6" x6". Inside I have set a baffle so that the oil return will not be interfered with . The whole idea about this item is that oil should be allowed to drain down from the turbo with no obstacle. This is the logic of the stock VW discharge (to the oil pan) and I have stuck to it. On my system the oil is being discharged through a 3/8" hydraulic hose crimped at both ends. The fill cap is also a vent. I bought it (cheap) at Princess Auto, it is a product used on hydraulic tanks. Note that the can will be filled only up to 2/3 of its height to allow for oil expansion and bucket effect. The total oil volume is then 1200 cc.
2) The oil pump is a 12 volt pump bought at Summit Racing. It is a positive displacement piston/diaphragm type of pump designed for continuous use.
3) Oil filter and filter head 1/2" NPT bought at Princess Auto in the same department. I made the stand.
4) A small oil radiator Rapid-Cool from NAPA. It will be straped to the main (water)radiator.
5) Home made Oil temperature/oil pressure switch. This unit will send a panick signal to two red lights when needed.
Next these will be plumbed permanently in my car. The actual setting may be of limited interest to you since my car is not a VW but a homebuilt sportscar with a longitudinal engine and Suzuki transmission. This means that a good deal of features have be modified to meet this car. If any one is interested I will show pictures later.
Testing of this lubrication system will not be done until May/June when I finally roll the car out.
I am available for more details if I can be of use.
Haybayian.
(http://i27.tinypic.com/1624s2o.jpg)
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Why not run a oil/water core? Some garretts are dual cooled. My IHI 5RHB in my old Thunderbird TurboCoupe was that. Far simpler, just need to run a tap off the coolant line to and from the turbo.
A good point.
Yes I am aware of the water cooled turbos. Improved cooling is a step in the right direction but does not address the "questions" that my post raised:
1)oiling the turbo's journals before the engine's oil pump kicks in and after it has stopped. And I was also suggesting that a separate system would allow the use of a different high speed bearing oil for the turbo only.
The bottom line is that no system is perfect. The system that I am suggesting is not complicated and not expensive...in the scale of the things that are discussed on this forum.
Haybayian
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why use the same weight oil as in your engine when you don't have to? i would use the thinnest weight oil you can get that has good protection. maybe the elf 0w30 economy oil? the turbo will spool so much quicker with a thinner oil :wink:
good luck on your project!
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Does the flowrate of oil to the turbo need to be varied according to the speed of the turbine? I'm thinking at engine idle when turbine is barely rotating will the excessive oil squirt out of bearings and into intake or exhaust? Or is this wrong thinking and the bearings free draining?
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Does the flowrate of oil to the turbo need to be varied according to the speed of the turbine? I'm thinking at engine idle when turbine is barely rotating will the excessive oil squirt out of bearings and into intake or exhaust? Or is this wrong thinking and the bearings free draining?
I don't believe that high oil pressure at low turbine speed should have any particular effect on the bearings' seals. These seals must be designed to sustain a given oil pressure no matter the rotating speed. The Tilton electric pump is rated to produce a maximum of 60 psi which is a safe range considering the Garrett turbo is designed to handle a maximum of 70-80 psi in VWs.
If I am wrong , of course, I would like to know.
Haybayian