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Thread: engine lubricant temperature reduction

  1. #1

    engine lubricant temperature reduction

    I need to reduce the lubricant temperature in a motorcycle engine.?

    I've been allotted this project in a motorcycle company in India in which I need to reduce the average temperature to which a lubricating oil gets heated up, in an engine for one of their models. Now I did see the flow path of the lubricating oil - sump to a filter, filter to a gerotor pump, to the gallery - splitting up to the crankshaft (through a centrifugal filter) and to the cylinder head, after which it lubricates the piston, valvetrain, timing chain and drops into the sump back again. Now I don't have a clue of how to REDUCE the temperature to which it heats up. Here are some facts:

    a) They recommend 10W30 for use as lube in that engine. So do I try measuring the temperatures with 20W50 or something? I've heard that higher the viscosity index after that W, higher is the high temperature performance, although I'm not so sure of how changing the oil would reduce the average temperature it gets heated up to.

    b) Does introducing an oil restrictor have any effect?

    c) Is it of any use trying to change the quantity of lubricating oil? 900 ml is the lube oil capacity of that engine, so what will happen if I pour 1000 ml of lubricating oil and perform that test?

    d) Changing the oil pump. That does have an effect, but that's the only thing that I've tried so far and I need more ideas.

    e) Changing the oil filter. Will that have any effect on the TEMPERATURE? If so, HOW?

    I need to finish this project within a month and I absolutely haven't a clue of what and how to do this. PLEASE HELP!

  2. #2
    Technical Fellow
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    Hi, a thorny problem. Unless you can turn around the basic Laws of Physics, there is not much (anything) you can do without making physical changes to the engine, or adding an oil cooling method.

    a) HUH?
    b) Yes, this will keep the oil longer in contact with the hotter parts of the engine. Not what you need.
    c) Yes, definitely, BUT you will need to also increase the holding capacity of the engine. Adding more oil will help reduce temps but the increase oil level in an unmodified sump will add other problems with the rotating masses. Excessive cylinder wall coating, piston bypass etc.
    d) Don't understand how!
    e) If it is an external oil filter you could try adding aluminum fins (anodized matte black) to it and make sure it is in a good air-flow position

    f) Add an external oil tank for increased oil volume without raising the current internal oil-level.

    g) I have been wrong before!

  3. #3
    Lead Engineer RWOLFEJR's Avatar
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    Type "motorcycle oil cooler kit" on your search engine.

  4. #4
    Quote Originally Posted by PinkertonD View Post
    Hi, a thorny problem. Unless you can turn around the basic Laws of Physics, there is not much (anything) you can do without making physical changes to the engine, or adding an oil cooling method.

    a) HUH?
    b) Yes, this will keep the oil longer in contact with the hotter parts of the engine. Not what you need.
    c) Yes, definitely, BUT you will need to also increase the holding capacity of the engine. Adding more oil will help reduce temps but the increase oil level in an unmodified sump will add other problems with the rotating masses. Excessive cylinder wall coating, piston bypass etc.
    d) Don't understand how!
    e) If it is an external oil filter you could try adding aluminum fins (anodized matte black) to it and make sure it is in a good air-flow position

    f) Add an external oil tank for increased oil volume without raising the current internal oil-level.

    g) I have been wrong before!
    Does drilling holes in the crankcase help as far as the return path of the oil is concerned?

  5. #5
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    Quote Originally Posted by csiddharthn View Post
    Does drilling holes in the crankcase help as far as the return path of the oil is concerned?
    I assume you mean enlarging the return-oil-ways. The answer is "NO" you are using the oil to move heat around and that is a finite loop. Unless you increase the ability to dissipate some of that heat then nothing is going to change except your perplexed expression. You do seem out of your depth here. There is no magic answer to this, an external cooler of some kind is the only way to solve this without major design changes to the engine itself.

  6. #6
    Associate Engineer
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    I work for a company called Vestas aircoil who design and manufacture charge air coolers. Typically these are designed to cool air from a turbo charger before it enters the engine and mixes with the fuel. I am sure that lube oil coolers are used for machinery and work using similar principles.

  7. #7
    Principle Engineer
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    Actually the heavier oil will increase the viscous friction a bit and defeat the purpose. That is the trade off for a thicker film.

    Examine the oil circuit for the relief valve flow. If the relief valve dumps the oil into the crankcase re-route the flow of the relief valve back into the oil pickup. This can reduce the amount of oil being drawn into the pump and the amount of work performed on the oil.

    Can you screw on a bigger filter for more surface area?

    Increase air flow by any means possible.

  8. #8
    Associate Engineer
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    Hi, I have just read through this post and maybe you need a lube oil cooler. I work for a company who deign and manufacture diesel engine charge air coolers. Generally designed to cool the hot compressed air from the turbo which enters the engine. Cold water passes through the cooler with the hot air passing through it also the water cools the air. I am sure that this approach can be used to cool oil.
    Last edited by Kelly Bramble; 07-06-2015 at 08:11 AM.

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