# Position of the piston of engine with respect to crank angle

Not Reviewed
x =
Tags:
Rating
ID
EmilyB.Position of the piston of engine with respect to crank angle
UUID
58597a45-57ee-11e6-9770-bc764e2038f2

The Position of the piston of engine with respect to crank angle calculator computes the position of a piston pin from the crank center based on the rod length, the crank angle and the crank radius.

INSTRUCTIONS: Choose units and enter the following:

• (r) This is the crank radius
• (A) This is the crank angle
• (l) This is the rod length.

Piston Position (x): The position is returned in inches.  However, this can be automatically converted to compatible units via the pull-down menu.

#### The Math / Science

The Position of the piston of engine with respect to crank angle expresses the motion of a non-offset piston connected to a crank through a connecting rod (as would be found in internal combustion engines).  The formula for the piston position is:

x=rcosA +sqrt(l^2-r^2sin^2A)

where:

• x = piston position
• r = crank radius (distance between crank pin and crank center)
• A = crank angle (from cylinder bore centerline at TDC)
• l = rod length (distance between piston pin and crank pin)