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Thread: Forged or Billet 4340 Crank /vs./ Machined OEM Crank

  1. #1
    Not known unless ur blown Backyard Mechanic
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    Default Forged or Billet 4340 Crank /vs./ Machined OEM Crank

    Why would you use a billet or forged 4340 crank over an OEM?

    I'm just curious as to what is the real value of changing from the stock crank?
    Reduced rotating mass, wear resistance, and strength is a given.
    But is it bang for your buck?

    For less money you can no doubt get the OEM crank machined sufficiently i.e. knife-edged, lightened, balanced and nitrided.

    So when doing this kind of thing is it better to go overboard or just spend it on something else more useful?

    Billet 4340 - knife-edged, lightened, balanced and nitrided.
    or
    OEM - knife-edged, lightened, balanced and nitrided.

    Cheers for any information guys.
    Last edited by Radar; 11-09-2009 at 12:50 PM.

  2. #2
    jetpilot Automotive Encyclopaedia 1JZ.747's Avatar
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    Default Re: Forged or Billet 4340 Crank /vs./ Machined OEM Crank

    what motor?
    8.3 et PB 169 MPH PB

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    Default Re: Forged or Billet 4340 Crank /vs./ Machined OEM Crank

    Did some research and came up with this...

    Typically OEM cast-iron cranks have a tensile strength of 65-80,000 psi with an elongation of 3%.
    Some improved cast-iron cranks have a tensile strength of 100,000 psi and an elongation of 5-6%

    Forged steels such as 4340 have a tensile strength of 140,000 psi and an elongation of +22%.

    *http://www.scribd.com/doc/11454996/H...-a-Crankshaft*

  4. #4
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    Default Re: Forged or Billet 4340 Crank /vs./ Machined OEM Crank

    2TC. Can get a billet one for $1800 USD

  5. #5
    Car Butcher Carport Converter WDE_BDY's Avatar
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    Default Re: Forged or Billet 4340 Crank /vs./ Machined OEM Crank

    What you have to look at is are people breaking cranks at the power you want? If not then its a waste of $$$.

    Callum

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    Default Re: Forged or Billet 4340 Crank /vs./ Machined OEM Crank

    Quote Originally Posted by WDE_BDY View Post
    What you have to look at is are people breaking cranks at the power you want? If not then its a waste of $$$.

    Callum
    spot on 1800, fugg that
    8.3 et PB 169 MPH PB

  7. #7
    doctor ed Conversion King ed's Avatar
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    Default Re: Forged or Billet 4340 Crank /vs./ Machined OEM Crank

    most oem toyota cranks are forged, not cast anyway. so data abpve most likely irrelevant
    ../delete/ban
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    E46 M3 Nürburgring Nordschleife - 8.38

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    Default Re: Forged or Billet 4340 Crank /vs./ Machined OEM Crank

    Cheers, I originally started checking out the crank when I saw a hotted up 2TC for sale with 50mm mikuni carbs and one of these 4340 billet cranks. The motor was putting out 200hp NA so I guessed that maybe the crank might be a worth while item.
    Wasn't sure if it was a worth while bang for buck item so I asked.
    Also didn't even think to question if Toyota OEM cranks are forged, thanks for that bit of info.
    I guess for 1800 a better bang for buck item would most defiantly be a Kenny Bell S/C.

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