Most motor vehicles today use an internal combustion engine (ICE) to provide them with the power needed to drive down the road; ICEs are a form of heat engine. Gasoline is burned to push a piston, which in return pushes the car down the road. When the gas in the cylinder is ignited and expanded, it pushes the piston along the shaft. The force is transmitted through the piston, which is connected to a crankshaft. The force moves through the transmission, up the driveshaft, and out of the tires. The Otto Cycle is used to transform as much heat as possible into driving force. “A heat engine is a machine that converts heat into work” (Heat engines). A heat engine absorbs a quantity of energy from a hot tank, works and then releases a quantity of energy to the cold tank. In the example of an ICE, gasoline is burned, creating heat and expanding the gases. This expansion pushes the piston down in the cylinder and the excess heat is expelled through the cooling system or exhaust. The work done by the engine can be determined using the equation: W=Q(hot) - Q(cold)The efficiency of a heat engine can be determined using the equation: e=W/Q(hot) petrol have four strokes and six processes in each cycle. During the intake stroke, air and fuel are drawn into the cylinder; increase in volume and potential energy. Subsequently, the compression stroke compresses the gases adiabatically; the volume decreases and the temperature increases. The spark does not occur during a stroke but when the piston is fully raised, this causes the gases to ignite while keeping them at relatively the same volume. In the power stroke, the gas expands adiabatically; the temperature decreases and the volume increases. Finally, the exhaust valve is opened so that during the exhaust stroke, as the piston moves upwards, gases are released causing a decrease in volume. A Hemi engine refers to the way the pistons, heads, and block are designed. This type of engine claims to provide better airflow within the cylinder creating more space for larger valves which in turn provide more power. The chamber of an hemi is hemispherical instead of being flat like traditional engines. This shape provides more surface area on the block allowing room for larger valves. When the engine breathes better there is less friction and a cleaner air/fuel mixture that provides more power.