Definition:
The Otto cycle engine is based on four strokes (reciprocating motions) of the piston for each power cycle.
- Intake stroke - the piston moves down and air and fuel is pulled into the combustion chamber.
- Compression stroke - the piston moves up and the air and fuel is mixed and compressed.
- Power stroke - the fuel/air mixture is ignited and the piston is forced down.
- Exhaust stroke - the piston moves back up and expels the spent exhaust gases making way for a new intake stroke.
As shown above, the piston travels up and down four times, but only one of those strokes produces usable power.
Examples:
Nearly every modern vehicle engine (with the exception of the Mazda Rotary) is based on the 4-stroke Otto cycle.The Alternative Fuel Bible: Find Answers to Your Fuel & Vehicle Questions