The HSI engine uses compression to ignite rather than sparks.

Diesel engines have several advantages over other internal combustion engines:

Diesel engines have several distinct advantages over different kinds of internal combustion engines:

Perhaps most important, the HCCI engine is not locked into having just enough air to burn the available fuel, as is the SI engine.

At least one swirl port (10p) and at least one tumble port (11p) communicate with a combustion chamber (13) of the HCCI engine (1).

According to Green, ignition timing in an HCCI engine depends on two factors: the temperature of the mixture and the detailed chemistry of the fuel.

In the HCCI engine, fuel is uniformly mixed with air (hence, "homogeneous charge), as in a spark-ignition engine, but with a higher proportion of air to fuel.

In the HCCI engine, fuel is uniformly mixed with air (hence, “homogeneous charge), as in a spark-ignition engine, but with a higher proportion of air to fuel.

In an HCCI engine, there is no need for a quickly spreading flame because combustion occurs throughout the combustion chamber.

According to Professor William H. Green, Jr., of the Department of Chemical Engineering, ignition timing in an HCCI engine depends on two factors: the temperature of the mixture and the detailed chemistry of the fuel.

So while the HCCI engine performs well under controlled conditions in the laboratory, it is difficult to predict at this time what will happen in the real world.