Torque Cars

All you need to know:Crankshafts

Discussion in 'Engine questions' started by obi_waynne, 30 June 2017.

  1. obi_waynne

    obi_waynne Administrator Staff Member Moderator

    Messages:
    41,202
    From:
    Deal, Kent UK
    Car:
    A3 1.4 TFSI 150 COD
    Last edited: 30 June 2017
  2. TCJBOLDIE

    TCJBOLDIE Torque King

    Messages:
    4,776
    From:
    Brisbane
    Car:
    JB Starion
    Hi Obi San can you explain what you mean by "short throw pistons" please?
     
  3. obi_waynne

    obi_waynne Administrator Staff Member Moderator

    Messages:
    41,202
    From:
    Deal, Kent UK
    Car:
    A3 1.4 TFSI 150 COD
    A piston that has a short stroke is what I had in mind?
     
  4. TCJBOLDIE

    TCJBOLDIE Torque King

    Messages:
    4,776
    From:
    Brisbane
    Car:
    JB Starion
    Obi San not wanting to start a war just wanting to clarify things :)

    The pistons stroke is determined by the crankshaft so the EXACT same piston can be used in a longer stroke application with a shorter rod length to stop the piston crown @ TDC extending past the top of the block however I would not recommend using shorter rods as that increases the piston skirt side loading .

    As an example my motor is a 4G63 (2.0 litre 88mm stroke) stroker where I have installed a 12mm longer stroke crank from a 4G64 motor (2.4 litre 100mm stroke) in a 2.0 block which increases the capacity to 2.3 litres .

    To do this the forged pistons fitted to the forged standard length 2 litre rods have the gudgeon pins raised 6mm (1/2 the increased stroke) and unfortunately that has lowered the rod ratio from 1.7 to 1.5 which has limited my redline to 7200 rpms

    I have started a new thread "Rod Ratios" for those who want to know more about the subject :)
     
    Last edited: 30 June 2017
    Lunchmoney, obi_waynne and thexav like this.
  5. thexav

    thexav Pro Tuner Staff Member

    Messages:
    2,044
    Car:
    2002 Clio 172
    Good article. A picture of the crankshafts would be good comparing flat plane to cross and the floating arm one.

    It was quite informative and written simply so I could understand it.

    What is crank grinding and knifedging and how does this improve performance?
     
  6. obi_waynne

    obi_waynne Administrator Staff Member Moderator

    Messages:
    41,202
    From:
    Deal, Kent UK
    Car:
    A3 1.4 TFSI 150 COD
    Much appreciated @TCJBOLDIE I'll make the article a little clearer.

    @thexav I don't have any pictures to use but I'll ask around and try and get permission to use some pictures from another tuner.
     
Loading...

Share This Page

Click Here
  1. This site, like pretty much every other site, uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are agreeing to our use of cookies, this may include third party cookies from our carefully selected advertising partners and for our analytics which allow us to see which pages are of interest and improve our site navigation and experience.
    You can disable cookies in your browser but this may affect your experience on this website.

    Dismiss Notice