Cubic Inch Displacement formula question?
07-19-2008, 10:39 PM
#1
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Cubic Inch Displacement formula question?
Please help me figure out what I'm doing wrong.
A 454 engine is= 4.250 diameter X 4.000 Stoke.
If you multiply 4.250 X 3.144 (pie)=13.362
13.362 X 4.000 (stroke)=53.448 cubic inches per cylinder
53.448 X 8 Cylinders =427.584 cubic inches, not 454.
What am I doing wrong?
I have a rebuilt engine with a 4.250 stroke and 4.250 pistons, I'm told its a 482, but using the math fomula above, it doesn't work out?? 4.250 x 3.144 x 4.250 x 8=454.308 cid.
Thanks for your help!
A 454 engine is= 4.250 diameter X 4.000 Stoke.
If you multiply 4.250 X 3.144 (pie)=13.362
13.362 X 4.000 (stroke)=53.448 cubic inches per cylinder
53.448 X 8 Cylinders =427.584 cubic inches, not 454.
What am I doing wrong?
I have a rebuilt engine with a 4.250 stroke and 4.250 pistons, I'm told its a 482, but using the math fomula above, it doesn't work out?? 4.250 x 3.144 x 4.250 x 8=454.308 cid.
Thanks for your help!
07-19-2008, 11:32 PM
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take the diameter of your piston and divide it by 2, this will give you the radius. square the radius (multiply it by itself ie: 2.125 * 2.125 = 5.516) take this number and multiply it by pi. you now have the area of the piston, for volume you just need the height so multiply that by your stroke. now just multiply that by your number of cylinders and you will have displacement.
3.14 *(2.125^2)= 14.179in^2 <--- area of the piston
14.179*4= 56.716in^3<--- volume of the cylinder
56.716*8= 453.73in^3 <--- Displacement your engine
3.14 *(2.125^2)= 14.179in^2 <--- area of the piston
14.179*4= 56.716in^3<--- volume of the cylinder
56.716*8= 453.73in^3 <--- Displacement your engine
07-20-2008, 08:46 AM
#7
Registered User
Formula for the volume of a cylinder-
1/2 the diameter of the bore (radius) multiplied by itself (squared, times 3.14 (pi)
Then-
that result times the stroke- that's individual volume
Then-
Multiply by the number of cylinders.
Example-
4.25" bore and 4" stroke
Divide 4.25 by 2= 2.125, times 2.25= 4.516.
Now multiply by pi- 4.516 times 3.14=14.18
14.18 times stroke (4) = 56.72
56.72 times 8 cylinders gives you 453.76 ci
Eddie's formula is simpler, but I can never remember it. I can remember pi. Because my 5th grade teacher beat this into me- "Pies aren't round, pi are square"
1/2 the diameter of the bore (radius) multiplied by itself (squared, times 3.14 (pi)
Then-
that result times the stroke- that's individual volume
Then-
Multiply by the number of cylinders.
Example-
4.25" bore and 4" stroke
Divide 4.25 by 2= 2.125, times 2.25= 4.516.
Now multiply by pi- 4.516 times 3.14=14.18
14.18 times stroke (4) = 56.72
56.72 times 8 cylinders gives you 453.76 ci
Eddie's formula is simpler, but I can never remember it. I can remember pi. Because my 5th grade teacher beat this into me- "Pies aren't round, pi are square"
Last edited by Chris Sunkin; 07-20-2008 at 08:53 AM.
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