some simple math

[1fst400]

It has been a while scence math class. want to double check me?

Alright, a piston is 81mm in diameter. If I shave off 1.524mm how much is that in area or volume.



this is what I came up with

I did 81mm Radius which is 40.5mm
R x pie =127.21
so 40.5mm x 3.141=127.21

so 127.21mm x 1.524mm = 194


am I right?

[Ghost-Rider]

This thread reminds me of how much i suck at math....i scanned over it all real fast i hate math...

[Hondaracing819]

if you want to find the area of the piston you need to do pi x radius squared

so

81/2=40.5

3.14x(40.5x40.5)=5150mm

then 81-1.524=79.476

79.476/2=39.738

3.14x(39.738x39.738)=4958mm

5150-4958=192mm

[pro-rider46]

hes not trying to find the surface area, he trying to figure out the volume.

heres a link to help figure out volume
http://www.math.com/tables/geometry/volumes.htm

[wilkin250r]

Let me make sure I have this correct.

You are shaving 1.524mm off the TOP of the piston, and you are trying to find out how much volume has changed?

You are close. Like Hondaracing819 said, you need radius squared.

81mm diameter is 40.5mm radius.

Radius squared times PI is "40.5*40.5*3.1416=5153"

This means the AREA of the piston is 5153 square millimeters.




To find VOLUME, you multiply the AREA times DEPTH, in this case the DEPTH is the 1.524 that you shave off.

5153*1.524=7853.172 cubic millimeters.

To change cubic millimeters into cubic centimeters (cc), you need to divide by 1000, so 7853 becomes 7.853cc.

But this wouldn't be accurate for the majority of the pistons out there, because most pistons have a dome on top, so the 1.524mm wouldn't be across the entire piston area.

[1fst400]

alright. sweet. I just couldent remember quite how to do it