When the modification is done, the cycle becomes Atkinson cycle (expansion ratio is greater than compression ratio).

The Atkinson cycle features a compression stroke that is shorter than the power stroke, achieved by leaving the intake valve open longer.
This effectively allows the gases to expand more than they are compressed and thus the gas does more work per stroke than in the Otto Cycle.
By getting more work out of a given amount of gas, the efficiency of the engine is improved.


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