What is the Otto Cycle?

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.

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