I’m gonna make this an extremely short answer because I’m sure someone will explain it better. So those pistons/cylinders in the engine systems subject to the ideal gas law, PV=nRT. With gas, it obviously has a hot combustion point that would overheat an engine quickly if all the energy was released at once. You don’t want that. So you want the change in temperature for each reaction to be very slow. This gets accomplished by changing both the pressure and volume inversely to each other so that the energy of the system doesn’t change much. The other part of how that is accomplished is by having a very small amount of the substance, n, to the point where it is close enough to 0 to a relatively insignificant increase in temperature per reaction. This is called an [adiabatic process or reaction](https://en.wikipedia.org/wiki/Adiabatic_process) It’s why engines warm up slowly as well. The pistons are also synchronized in some way that one reaction will transfer some of its energy to the mechanical energy of the piston, starting that reaction and so on…
**tl;dr**: use a miniscule amount of gas, piston pump it to raise the pressure and lower the volume so the reactions slowly and efficiently happen and some of that mechanical energy gets transferred in a cascade to the other pistons to continue getting that power.
Latest Answers