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Automotive Car Question Acceleration vs. Engine Life

  1. Apr 13, 2016 #1
    What's going to let an engine last longer:

    1) Accelerating quickly to just above desired speed and coasting until speed drops

    2) Holding engine at a more constant lower rpm to achieve that desired speed

    I know to some extent 1) is better for fuel when the acceleration isn't too hard but that's not what I'm asking
  2. jcsd
  3. Apr 13, 2016 #2
    Automatic or stick?
  4. Apr 14, 2016 #3
    This is impossible to answer. In theory the loads under acceleration would impart more wear than the benefit gained from coasting (and I'll assume shifting to neutral while coasting). But that could change based on how hard you accelerate each time, numerous design details in the engine, how the engine responds to idling, etc., etc.
  5. Apr 15, 2016 #4
    Sounds about right
  6. Apr 15, 2016 #5
    my hypothesis is, slow to speed will always win for this question in this context. the reason being, heavy acceleration puts way more force onto the lubrication and depending on how much force is needed the oil might shear. heavy car vs light car will make a diff, etc.

    if there is guarantee that the motor oil does not shear under all test conditions, and every mating surface is protected in some way, then there is likely no diff in longevity of the motor, well, constant sudden bursts from injectors may have a negative impact.
  7. Apr 16, 2016 #6
    Friction increases logrithmically. Higher engine speeds with higher loads will cause more wear. However, even an engine driven vigorously but well maintained will last 2 to 3 hundred thousand miles. I am a technician and see quarter million mile cars every week. Some of these are beat so wear by driving style is not as important as wear from lack of maintenance.
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