Best stroke size for Hemi

Discussion in 'PSI Superchargers Tech Questions' started by Money Shot, Jun 4, 2012.

  1. Money Shot

    Money Shot Member

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    I'm sure I'm gonna get 50 different answers but here goes. I've been running a 4.500 stroke crank in a std deck KB Stage 5 block with a 7.11 length rod. The combination makes good power but it seems this stroke combination is hard on rods. I've also noticed the rod is very close to hitting the cam. I've thought about changing to a 4.375 or even 4.15 to gain better rod geometry and cam clearance. Has anyone had better luck with a shorter stroke vs a longer one?
     
    #1
    Money Shot, Jun 4, 2012
  2. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    Stroke

    On a budget, ideally the shortest stroke you can get away with.

    The force exerted on the big end of the rod gets exponentially greater with increased stroke.

    Also, since you race in a limited blower overdrive series, smaller CID may become an advantage. If you look at any weight break or restricted blower class, boost per cid becomes more important than CID. The smaller motor will make the blower more efficient.

    I would build something in the neighborhood of 3.900 to 4 inch stroke and big bore (4.4675). You should be able to turn this 9500 to 10000 with no drama, just keep good valve springs in it.
     
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    Will Hanna, Jun 5, 2012

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