Question for the engineers.
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  1. #1

    Question for the engineers.

    To the mechanical engineers in the group. Is the movement of the pistons in relation to the frame responsible for the smoothness of the flat engine? The BMW is very similar but I have never been on one to compare.

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  2. #2
    Moderator BIGLRY's Avatar
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    "A flat-6 or horizontally opposed-6 is a flat engine with six cylinders arranged horizontally in two banks of three cylinders on each side of a central crankcase. This should not be confused with the Opposed-piston engine. The pistons are mounted to the crankshaft such that opposing pistons move back and forth in opposite directions at the same time, somewhat like a boxing competitor punching their gloves together before a fight, which has led to it being referred to as a boxer engine.
    The configuration results in inherently good balance of the reciprocating parts, a low center of gravity, and a very short engine length.
    The movement of the pistons in a horizontal engine is all in the same plane, so it creates less vibration than in a V-configuration engine; particularly one, like a V6, with an odd number of cylinders on each side of the engine. Unlike the V6 but like the inline-6, the flat-6 is a fully balanced configuration which is in perfect primary and secondary balance. The three cylinders on each side of the crankcase tend to have an end-to-end rocking motion, like a pair of inline-triple engines, but in the usual boxer engine configuration, the imbalances on each side cancel each other, resulting in a perfectly smooth engine.

    The flat-6 is also smoother than the flat-4 or inline-4 because the power strokes of the cylinders overlap in a four-stroke cycle engine. In these four-cylinder configurations, pistons are 180 degrees apart in crankshaft rotation and start their power strokes every 180 degrees, so each piston must come to a complete stop before the next one commences its power stroke. In the flat-6, each power stroke begins 120 degrees after the previous one starts, resulting in 60 degrees of overlap between power strokes and a much smoother delivery of power to the flywheel."
    https://en.wikipedia.org/wiki/Flat-six_engine



    I am not an engineer, but I did sleep at home last night.

    The guy who invented the first wheel was an idiot -
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  3. #3
    Quote Originally Posted by BIGLRY View Post
    "A flat-6 or horizontally opposed-6 is a flat engine with six cylinders arranged horizontally in two banks of three cylinders on each side of a central crankcase. This should not be confused with the Opposed-piston engine. The pistons are mounted to the crankshaft such that opposing pistons move back and forth in opposite directions at the same time, somewhat like a boxing competitor punching their gloves together before a fight, which has led to it being referred to as a boxer engine.
    The configuration results in inherently good balance of the reciprocating parts, a low center of gravity, and a very short engine length.
    The movement of the pistons in a horizontal engine is all in the same plane, so it creates less vibration than in a V-configuration engine; particularly one, like a V6, with an odd number of cylinders on each side of the engine. Unlike the V6 but like the inline-6, the flat-6 is a fully balanced configuration which is in perfect primary and secondary balance. The three cylinders on each side of the crankcase tend to have an end-to-end rocking motion, like a pair of inline-triple engines, but in the usual boxer engine configuration, the imbalances on each side cancel each other, resulting in a perfectly smooth engine.

    The flat-6 is also smoother than the flat-4 or inline-4 because the power strokes of the cylinders overlap in a four-stroke cycle engine. In these four-cylinder configurations, pistons are 180 degrees apart in crankshaft rotation and start their power strokes every 180 degrees, so each piston must come to a complete stop before the next one commences its power stroke. In the flat-6, each power stroke begins 120 degrees after the previous one starts, resulting in 60 degrees of overlap between power strokes and a much smoother delivery of power to the flywheel."
    https://en.wikipedia.org/wiki/Flat-six_engine



    I am not an engineer, but I did sleep at home last night.
    Thank you, do you think Harley will ever catch on?





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  4. #4
    Senior Member bobbyf6b's Avatar
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    The boxer analogy doesn't make sense to me. If it was like a boxer punching his gloves together then the pistons would be facing each other.

  5. #5
    Moderator BIGLRY's Avatar
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    Quote Originally Posted by Retired Army View Post
    Thank you, do you think Harley will ever catch on? No and because they are so entrenched with promoting the H-D almost spiritual mystic image and global marketing that any radical changes will kill their market share and effect their bottom line. IMO





    You can sleep tonight, your Army is.
    good to know.

    The guy who invented the first wheel was an idiot -
    the guy who invented the second one... he was the genius!


    http://theringfinders.com/blog/Larry.Royal/

  6. #6
    Moderator BIGLRY's Avatar
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    Quote Originally Posted by bobbyf6b View Post
    The boxer analogy doesn't make sense to me. If it was like a boxer punching his gloves together then the pistons would be facing each other.
    See if this helps.
    first a four cylinder

    Now a six, you can see the 120 deg power stroke with the 60 deg overlap in the six, while the 180 deg four meet together at the same time.


    Look at the bases or rod ends of the pistons touching like a boxers punching their gloves together before a fight, not the tops of the pistons, it is much more obvious in the four cylinder engine.
    The term Boxer came from the original Porch four cylinder engine, but is used universally now for any 180 deg opposing piston engine.

    The guy who invented the first wheel was an idiot -
    the guy who invented the second one... he was the genius!


    http://theringfinders.com/blog/Larry.Royal/

  7. #7
    Junior Member StraightWings's Avatar
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    smoooothie

    Both the bike and the summation regarding the engine. Excellent explanation. Nice work, Biglry.

  8. #8
    Mystic makes me really ill I can't even stand next to it.

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  9. #9
    Moderator BIGLRY's Avatar
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    Quote Originally Posted by Retired Army View Post
    Mystic makes me really ill I can't even stand next to it.
    ˈMYSTIC:
    noun: mystic; plural noun: mystics
    a person who seeks by contemplation and self-surrender to obtain unity with or absorption into the Deity or the absolute, or who believes in the spiritual apprehension of truths that are beyond the intellect.
    https://www.google.com/search?source...US515&q=Mystic


    or were you perhaps thinking of MASTIC the glue?

    The guy who invented the first wheel was an idiot -
    the guy who invented the second one... he was the genius!


    http://theringfinders.com/blog/Larry.Royal/

  10. #10
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    Very good explanation.....

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