HCCI Engine Technology

Homogeneous Charge Compression Ignition (HCCI) is an advanced futuristic combustion technology for internal combustion (IC) engines. HCCI engine technology offers high thermal efficiencies and low NOX and particulate matter (PM) emissions. Similar to spark ignition (SI) engines, the charge is premixed thus reducing the PM emissions, and as in compression ignition direct injection (CIDI) engines, the charge is compression-ignited.



General Motors first showed off its prototype Homogeneous Charge Compression Ignition (HCCI) engines last summer in an Opel Vectra and a Saturn Aura. We had the opportunity to drive these vehicles at GM's Milford Proving Ground at a very early stage of development. Because HCCI only works at part throttle conditions (while engines in cars have to work under all conditions), these new power plants have the ability to switch modes on the fly between HCCI and spark ignition. When we drove the cars, the HCCI only operated when driving at up to 55mph. At higher speeds or loads or when idling, the engine was in normal spark ignition mode.

An HCCI engine ignites a mixture of fuel and air by compressing it in the cylinder. Unlike a spark igni- tion gas engine or diesel engine, HCCI produces a low-temperature, flameless release of energy throughout the entire combustion chamber. All of the fuel in the chamber is burned simultaneously. This produces power similar to today's conventional gas engines, but uses less fuel to do it.
HCCI builds on the integration of other advanced engine technologies – some of which are already in production and can be adapted to existing gas engines. The cylinder compression ratio is similar to a conventional direct-injected gas engine and is compatible with all commercially available gasoline and E85 fuels.