Page Title My inspiration for this, similar to my last engine animation, came from here: Animated Engines - Atkinson

Speed

The reason for this arrangement of rods is that it makes it so that the total amount of volume at the end of the power stroke is more than that at the end of the intake stroke. This is good because it means that the hotter, higher pressure combusted gasses can expand fully since they take up more volume than when uncombusted because they are much hotter. This means that less energy is wasted when the exhaust valve opens since there is less excess pressure, and since less energy is wasted there is a higher overall eficiency. Total power is reduced however, but the fuel consumption is reduced even more. Modern cars that are said to use the "Atkinson Cycle" do not use the arrangement of rods shown here, but instead stay with the much simpler and more compact standard configuration and achieve the same effect with variable valve timing. The intake valve is left open even after the piston begins to rise causing some of the fuel-air mixture to be pumped back out so that it achieves the same effect as a shorter intake stroke. (By Jason Stone, age 14)

Atkinson “Cycle Engine” Animation