Orange area illustrates displacement.
Inspired by the large scale RC hobby, I created a few functions for calculating engine specifications.

Calculate volume by bore and stroke. (πr²h).
Bore/Cylinder Diameter (in mm):
Stroke (in mm):
 

Convert cc to liter.
Cubic Centimeters (cc):
 

Convert liter to cc
Liter:
 

Convert newton-meter to pound-foot force:
Nm:
 

Convert pound-foot force to newton-meter:
lb-ft:
 

Convert kilowatt to brake horsepower:
kW:
 

Convert brake horsepower to kilowatt:
bhp:
 

Convert rpm and torque to raw horsepower:
RPM (revolutions per minute):
Torque (lb-ft/pound-foot):
 

Convert raw horsepower to rpm:
HP (revolutions per minute):
Torque (lb-ft/pound-foot):
 

Convert raw horsepower to torque:
HP:
RPM:
 

Quick note: Don't confuse Pound-Foot (lb-ft) and Foot-Pound (ft-lb) Forces. They are not interchangeable.

The “pound-foot” (lb-ft)/torque is a unit of torque and a vector measurement that is created by one pound of force acting on a one foot lever.
The “foot-pound” (ft-lb)/energy is a scalar unit and measurement of work required to move a one pound object one foot of linear distance.