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How to cal. cubic inches?

Discussion in 'The Garage' started by Cornfield creations, Jul 31, 2006.

  1. Cornfield creations

    Cornfield creations 1/2 ton status

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    I wanted to know how to calculate cubic inches on a small block.

    I have a 327, bored .060 over, 9:1 aluminum flat top pistons and double hump heads, 64cc chamber.
     
  2. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Bore x Bore x Stroke x .7854 X the amount of cylinders (8 in this case).

    A 327 bored .060" is now a 336.6
     
  3. goldwing2000

    goldwing2000 Guest

    That's a weird formula. It seems to work but it's weird.

    I've always used the area of the bore (pi x the radius²)xthe strokexthe number of cylinders.

    Where do you get that .7854 constant from?
     
  4. MTMike

    MTMike 1/2 ton status

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    It appears to be based off of the square root of 1/2 of the bore/pi (hence the double multiplication of the bore)
     
  5. goldwing2000

    goldwing2000 Guest

    Man, that's complicated. :confused:

    I'll stick with regular geometry. :D
     
  6. MTMike

    MTMike 1/2 ton status

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    Thats about the extent of my knowlege of it - If you want more detailed info than that I can ask my 1-semester-away-from-a-math-degree wife :D
     
  7. goldwing2000

    goldwing2000 Guest

    Nah. I'm good with old "pi r squared". That's the way I was taught back in 1989, so that's what I'm going to use!
     
  8. boz42

    boz42 1/2 ton status GMOTM Winner

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    i always used the .7854 constant, i learned it that way 15 yrs ago
     
  9. BigBen

    BigBen 1/2 ton status Premium Member

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    area is pi * radius^2
    If you use bore, you are using the diameter.
    area is now pi* (diameter/2)^2
    Factor out the denominator and you have:
    pi*diameter^2/4
    or, diameter^2 * (pi/4)
    pi/4 is........................................



    .7854



    brought to you by the 'magic of math'!

    -Ben
     
  10. MTMike

    MTMike 1/2 ton status

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    I knew it was something like that but havn't done math like that since 1998 so I couldn't work out the equation..... :D
     
  11. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    I always forget the formulas , but I always remember every .030 is around 5 cubes for an 8 cylinder ( round up for advertising ) :thumb:
     

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