Which Would be Better, the S.I or C.I Engine, from the View Point of Fuel Consumption?

First, by means of the cycle theory the comparison study was made on the basic concept of fuel consumption in pre-mixed-homogeneous cycle and stratified-charge-heterogeneous cycle. In the next, the practical data of efficiency in both engines are compared and the differences arosen on efficiency and that causing reasons discussed basically on the view point of theory of cycle and combustion. Some suggestive conclusions were introduced as follows.

1. 1.
   Specific heat of gas during combustion is one of the most influencial factors on efficiency.
2. 2.
   The efficiency at low load in pre-mixed cycle is higher theoretically and practically lower than that operated at full load.
3. 3.
   if the lean homogeneous rapid combustion is attained, the efficiency will be dramatically high.
4. 4.
   The efficiency at low load in stratified charge cycle is higher theoretically and practically than that operated at full load.
5. 5.
   Stratified charge or C.I cycle has advantage in efficiency if pre-mixed-lean-mixture rapid combustion is unattainable in practice.
6. 6.
   A new hybrid concept of S.I and C.I engines is proposed as a total conclusion of this discussion.