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Cubic Inch question?

Discussion in 'The Hokey Ass Message Board' started by DocWatson, Mar 22, 2008.

  1. I did a search but couldn't find what I was looking for. I would like to work out what a 401 Nailhead cubic inch would be bored 30 thou over? How do I calculate that:confused:
    Doc.
     
  2. irishpol
    Joined: Jul 18, 2006
    Posts: 711

    irishpol
    Member
    from Texas

    Bore X Pi X stroke X the number of cylinders.
     
  3. mac762
    Joined: Jun 28, 2007
    Posts: 676

    mac762
    Member

  4. thads31
    Joined: Jan 3, 2007
    Posts: 124

    thads31
    Member

    equation is: 0.25 x Bore x Bore x Pi x stroke x # of cylinders

    (circle area is Pi x radius squared)
     
  5. irishpol
    Joined: Jul 18, 2006
    Posts: 711

    irishpol
    Member
    from Texas

    Pi R Squared... your right... I must not awnser tecnical questions first thing in the morning:confused:
     
  6. Big Z
    Joined: Feb 13, 2008
    Posts: 29

    Big Z
    Member

    If you would've bought a hemi instead you wouldn't have this problem. jk
     
  7. AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAHHHHH!
    Knew it, should have bought a Hemi!

    Ok, so I need more info on my motor. Wouldn't have a clue about stroke and bore other than its .30 thou over and stock stroke (I don't even know what that is!), the motor is still on its way to me. I think I better invest in a better calculator, this one I got in a show bag just don't cut it!
     
  8. RichFox
    Joined: Dec 3, 2006
    Posts: 10,020

    RichFox
    Member Emeritus

    Bore X bore X .7854 X stroke X number of cylinders. Pie is for eating.
     
  9. Why cant I find any info on the stock stroke? Anyone know what it is?
     
  10. Scott
    Joined: Dec 23, 2004
    Posts: 2,773

    Scott
    Member

  11. Big Z
    Joined: Feb 13, 2008
    Posts: 29

    Big Z
    Member

    I may be wrong, bore 4.1875 stroke 3.640. with .03 over i get 407
     
  12. Scott
    Joined: Dec 23, 2004
    Posts: 2,773

    Scott
    Member

    bore=4.1875
    stroke=3.640
     
  13. panic
    Joined: Jan 3, 2004
    Posts: 1,450

    panic

  14. Man, why cant I find that stuff when I look? I feel useless...........
     
  15. RichFox
    Joined: Dec 3, 2006
    Posts: 10,020

    RichFox
    Member Emeritus

    Buy an old Motors Manual on Ebay that covers the years you are interested in. The book has all the diminsions and torque specs. for all American cars made for 7 years before it's publishing date. All kinds of good stuff to look at cheap.
     
  16. WQ59B
    Joined: Dec 14, 2005
    Posts: 2,620

    WQ59B
    Member

    Yea: .030 on a Pontiac 400 is 6 cubes, I believe at .030 there is lots of rounding, so even with different bore/stroke sizes, .030 on a 400 V-8 is gonna work out to 6 cubes.
     
  17. hot rust
    Joined: Sep 18, 2007
    Posts: 790

    hot rust
    Member

    another formula is bore x stroke x 3.1416xno of cylinders
     
  18. Ruiner
    Joined: May 17, 2004
    Posts: 4,141

    Ruiner
    Member

    3.1416 is Pi, that's the same formula...
     
  19. Big Z
    Joined: Feb 13, 2008
    Posts: 29

    Big Z
    Member

    The actual formula is ci = (bore/2)sq x 3.1416 x stroke x num of cylinders;

    the area of a circle is A= pi(3.1416) x radius squared; bore is the diameter so u gotta divide by 2
     
  20. RichFox
    Joined: Dec 3, 2006
    Posts: 10,020

    RichFox
    Member Emeritus

    That works good as long as you have a 4 inch bore since the radius of a 4 inch bore is 2 inches and 2 squared is 4. It will not work with any other sizes bore. Say you had a 3.375 bore. Half that is 1.6875 times pi is 3.141. Won't work.
     
  21. texoutsider
    Joined: Jul 6, 2005
    Posts: 826

    texoutsider
    Member
    from Frisco, Tx

    406.81

    borexborexstrokex.7854x#of cyl...works for me. Have used this formula for many years.
     
  22. JHhj0978
    Joined: Nov 30, 2007
    Posts: 158

    JHhj0978
    Member
    from Youngstown

    yupp that works!
     

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