Knowing piston speed based on rod ratio and rpm?

[Donnie1126]

Using any rod ratio what is the best way to figure piston speed from 0 to 90 degrees at any rpm?

[Shaun]

I would think you just have to work out the trigonometry and calculate it

[Greenlight]

The mean piston velocity is:

Vmean = 2 x L x N

where

L = stroke
N = rotational speed of the crankshaft

The instantaneous piston velocity is:

Vi = Vmean x p/2 x sin q x [ 1 + ( cos q / ( R^2 - sin^2 q )^1/2 ) ]

where

p = PI or 3.14159
q = the crank angle relative to TDC
R = the ratio of the rod length to the crank radius