1) According to firing method i) Internally fired ii) Externally fired 2) Type of ignition i) SI (Spark Ignition) (petrol) ii) CI (compression Ignition) (Diesel) 3) Number of Cylinders i)...

Source - Wikipedia An external combustion engine (EC engine) is a heat engine where an (internal) working fluid is heated by combustion of an external source, through the engine wall...