[ mod note: moved from homework ] as a mechanical project we have been asked to design a micro steam car. we have chosen to use a wobbler engine for this. The aim of the project to see how far this car can travel based on a given amount of fuel. We are making a boiler which will provide the steam to run the piston but we have no idea on how to calculate the sizing of the piston. We are assuming the pressure in the boiler will be at 2 bar. how do I calculate the piston sizing ?