# How to cal. cubic inches?

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

1. ### Cornfield creations1/2 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. ### 4X4HIGH1 ton statusPremium MemberGMOTM 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. ### goldwing2000Guest

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. ### MTMike1/2 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. ### goldwing2000Guest

Man, that's complicated.

I'll stick with regular geometry.

6. ### MTMike1/2 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

7. ### goldwing2000Guest

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. ### boz421/2 ton statusGMOTM Winner

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

9. ### BigBen1/2 ton statusPremium Member

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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. ### MTMike1/2 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.....