High compression ratio gives high power to spark-ignition engine, hence there has been a tendency for combustion chamber shapes at T.D.C. As the piston moves down, the hot gases from the energy cell come in the main combustion chamber due to the pressure difference, creating the turbulence and making the complete combustion. The combustion takes place first in the main combustion chamber and then spreads up to the energy cell, where pressure increases. When the fuel is injected in the main combustion chamber, some part of it, about 10%, goes in the energy cell also.
When the engine is started, the narrow opening is opened which connects the major cell with the minor cell. At the time of starting the engine, the narrow opening is kept closed which increases the capacity of the combustion chamber.
