Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Magnesium engine

  1. Nov 30, 2008 #1

    wolram

    User Avatar
    Gold Member

    Why is magnesium not used much for engine castings? the old air cooled VW engines were light enough (bare) to be easily lifted by one person surely there is a big power to weigh ratio to be gained.
    If i remember correctly added copper reduced corrosion to after market castings.
     
  2. jcsd
  3. Nov 30, 2008 #2

    brewnog

    User Avatar
    Science Advisor
    Gold Member

    Cost, generally. A few of the German OEMs have started playing with it again recently, I think the new BMW I6 engines have a magnesium alloy block (albeit with an aluminium alloy cylinder liner).
     
  4. Nov 30, 2008 #3
    Magnesium is flammable. I'm not sure if engine temperatures would be high enough for ignition, but it is definitely something to consider.
     
  5. Nov 30, 2008 #4

    LURCH

    User Avatar
    Science Advisor

    A friend of mine had his engine catch fire in a parking lot. No way you can extinguish them once they get started. Also no way Gary is ever buying another engine with a magnesium block.
     
  6. Nov 30, 2008 #5
  7. Nov 30, 2008 #6

    mgb_phys

    User Avatar
    Science Advisor
    Homework Helper

    Magnesium is flammable but so is aluminium (ever heard of thermite?) Mg is 30% lighter than Al and 75% ligther than steel.
    You can put out a Mg fire - you just need the right sort of extinguisher (the same dry powder you need for Al), however if a fire is hot enough to burn an engine block you are generally better off just standing back and watching from a safe distance.
    Its generally failry safe in big blocks - it's very scary to machine though!
    I visited a contractor machining Mg gearboxes for Apache helicopters, you have to high speed machine parts without letting any chips touch air!
    You use a lot of coolant and they are very careul about sweeping the swarf.

    Generally it isnt used much becase the weight of cars hasn't mattered much, theres no point in saving 50Kg off the weight of the engine block if you put it in a 3000kg SUV.
     
  8. Dec 1, 2008 #7
    Isn't Magnesium also not very malleable? Wouldn't it give some issues with temperature gradients and cracking under high stress operation?
     
  9. Dec 1, 2008 #8

    mgb_phys

    User Avatar
    Science Advisor
    Homework Helper

    If you have the right alloy it can be worked pretty much the same as Aluminium.
    Not sure I would want to weld it though ;-)
     
  10. Dec 3, 2008 #9
    Welding magnesium just requires ensuring that a shielding gas surrounds the piece being welded with a short period of gas flow after the weld is completed.
     
  11. Dec 3, 2008 #10

    mgb_phys

    User Avatar
    Science Advisor
    Homework Helper

    In general yes - the danger is that sparks from an arc welding robot landing on the car.

    [​IMG]
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Magnesium engine
  1. Is there engineering (Replies: 8)

  2. Magnesium-based Stents (Replies: 4)

Loading...