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Thread: Pros / cons of lightened /aftermarket Crank Pulley ?

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    Pros / cons of lightened /aftermarket Crank Pulley ?

    Hey, l am putting together my CA18DET l bought for Lada engine swap and was looking at sourcing / fitting a lightened Crank Pulley. Is there much benefit to using lightened pulley ? Meant to improve throttle response and ‘reduce the rotating mass and uneseccary strain during hard acceleration. I have read a couple of posts though which reckon they can cause ‘balance’ issues with crank. I have a decent condition pulley, minus the front piece, has had a ‘trigger wheel fitted for Crank position sensor, could just take this to machine shop and get excess shaved off, l am not running power steering pump so don’t need the front pulley..
    This is my first time putting a CA together so trying to learn as I go !
    Any advice appreciated, cheers

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    id just run the standard one with the harmonic damper built in.
    a light weight flywheel is a good improvement for reducing rotational mass.

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    They dont have any dampening built in so it wouldnt be ideal to use.

    May be lighter but doubt you’d feel the difference


    Sent from my iPhone using Tapatalk

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    Member R3K1355's Avatar
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    You need the harmonic dampner in the pulley.

    ATI do (or did) an aftermarket pulley for the CA with a harmonic dampner.

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    Thanks.. just gonna stick with the standard one.. minus the front pulley as lm not running ps.. machined it back a couple of mil to clean it up, should do the job..

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    ��will have a look for future ref

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    Quote Originally Posted by jay1017 View Post
    They dont have any dampening built in so it wouldnt be ideal to use.

    May be lighter but doubt you’d feel the difference


    Sent from my iPhone using Tapatalk

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    I would make sure that machining was very evenly done.

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    if he did it in a lathe or a milling machine it will be fine.

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    Re :?? Harmonic damper.

    With every firing stroke the crank gets an impulse that twists it. At some engine revs these match the natural frequency or a harmonic of the cranks torsional frequency, like giving a shove to a swing at just at the right time so it goes higher and higher. Harmonic means 1/4x, 1/3x, 1/2x, 1x, 2x, 3x, 4x, this is like giving the shove only every 4th swing or 3rd swing or 2nd swing, every swing, twice per swing (gotta chase it - good way to get a mouthful of swing)...

    The rubber bonded ring on the front pulley resists the impulse and changes the natural frequency of the crank assy so it's no longer in the engine operation range.

    Cranks don't last very long if run at one of the many critical frequencies without the right damper.

    This analysis is for an inline 6 but it gives some idea of the process. Have fun re-analysing a 4 cylinder crank after you pretty and lighten it up by removing metal doing aero mods or replace it with an 8 counterweight one (hint works of CNC art are not always not good design).
    https://www.researchgate.net/publica...tal_validation

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