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Old 01-24-2007, 07:40 PM
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c.i.d formula

hey every 1 i have a question ?
in the c.i.d. formula what does the 0.7854 stand for

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Old 01-24-2007, 08:18 PM
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c.i.d. formula's

The number 0.7854 is 1/4 of 3.1416 (pi).
The formula I've found to be the simplest to use is: bore x bore x stroke x 6.2832 = cubic inches for a V8. Change 6.2832 to 3.1416 for a 4-banger or to 2.3562 for a 6-cylinder. See the connection? 2 pi ; 1 pi ; 1 and 1/2 pi.
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Old 01-24-2007, 10:39 PM
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pi r squared = area of circle


3.1416 * Radius * Radius = area of circle

In math the times and division parts of a formula can be moved around without changing the results.

Because of this:

Move Pi to end and you get

Radius * Radius * pi


bore / 2 * bore / 2 * pi

rearange it again to be

bore * bore * pi / 2 / 2


bore * bore * pi / 4


bore * bore * 0.7854

Got it?
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