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Engine lubricant temperature reduction

  1. May 19, 2013 #1
    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. jcsd
  3. May 19, 2013 #2


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    Two words: oil cooler.
  4. May 20, 2013 #3

    Ranger Mike

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    oil cooler
  5. May 20, 2013 #4
    Does the sump have cooling fins if not the addition of some might help, anything that increases the surface area of the sump will help. What about the air path over the sump is that restricted by anything, fairings or such?
  6. May 20, 2013 #5
    er... will this have any effect: drilling holes in the crankcase so that oil that lubricates the valvetrain --> piston --> gearbox --> sump through holes already available, flows more freely(? i'm confused) into the sump? Will the oil pressure decrease?
  7. May 20, 2013 #6


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    You've got to take heat away from the oil. I assume that all of the parts mentioned are already receiving sufficient lubrication, otherwise you would have a lot of seized motorcycle engines laying around. Like Jobrag suggested, the fix could be as simple as adding fins to the sump. You need to get information on how much of a temperature reduction is required.
  8. May 20, 2013 #7


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    In addition to the good suggestions posted above I will add the following.

    My old XT 600 had a remote oil tank that was placed away from the heat of the engine and exhaust. I am sure this helped.

    It also had about 3.0l of oil - 5 times the cc of the engine.

    I think increasing the oil capacity will help. The amount circulating around the hot parts of the engine is fixed for a given pumping rate. Increasing the the capacity will increase the amount of oil sitting in the sump and therefore the amount of time it has to loose heat before it gets sent around the hot parts again.
  9. May 20, 2013 #8


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    Are they going to share the profits with those who help?
  10. Jun 11, 2013 #9
    Did you manage to solve your problem?
  11. Jun 26, 2013 #10
    If sump have some fins type structure will be usefull or use oilcooler. Low viscosity oil good for less clearances like 10w30 .
  12. Aug 3, 2013 #11
    I did manage to reduce the temperature by increasing pressure at the crankpin outlet (enlarged that hole) although i have no clue of the physics that transpired!
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