I just had my raptor punched out .020 over w/ a 12:1 compression piston. I know .020 over doesn't make much off a difference, but i dont know how to do the actual math to see the final displacement. If anyone knows the equation or can tell me, it is appreciated.
jay[img]i/expressions/face-icon-small-happy.gif[/img]

 

Its just the volume of the cylinder with the stock stroke of 84mm that you are calculating. Here is the equation.

Total Disp.=Area of Piston * Length of Stroke

Total Disp.=(pi*radius^2) * 84mm

Total Disp.=(3.14159*50mm^2) * 84mm

Total Disp.=659.7cm^3 is stock(Convert from mm^3 to cm^3 for CC's move decimel 3 places left)

Convert your 0.020in into mm = 0.508mm So your new diameter is 100.508mm instead of 100mm which is stock. Don't forget to devide by 2 to use in the equation, its the Radius not the diameter.

Hope this helps!

 

I guess you've got a 666, sounds F'ing scary to me!

 

Here is the simple formula: Bore x Bore x.7854 x Stroke =CC's

 

Jay,

What "devil" told you to only go with the .020 666cc?? It is the same $$ to do the 102 and the performance increase is major.

 

jmc, your "simple formula" doesn't work. All you have done is work backwards to find a false conversion factor that has no application outside of a cylinder with a 100mm bore. If you change the bore, your .7854 conversion factor no longer works. You have to use the formula provided by ZRWHAT to actually figure out displacement for any engine.

 

I just did it on three different conversions, and it sure works for me.

 

JMC's formula works every way I tried it.

 

Try the following: bore x bore x stroke x 3.1416 = displacement. This always worked for me, but then again, math was always my worst subject!!!

 

CBUS66R
I think you had better think again.But then what would A.Graham Bell know anyway.100x100x.7854x84=659.736cc.Another eg.100.5x100.5x.7854x84=666.349cc.Do any bore and stroke you like.A retraction would be nice.