What is HCCI, and What Does it Mean for Efficiency
Has GM struck gold, 30 years later?
HCCI, which stands for Homogeneous Charge Compression Ignition, is currently under development at General Motors. Under the watch of Paul Najt, who worked on the technology during his days as a PhD researcher, HCCI is coming to the forefront of GM’s work on eco-friendly gasoline technology. The technology was put on the shelf years ago, but has made a comeback with several important improvements and a promise from GM to make it viable for use in passenger vehicles in the near future.
I recently had a chance to try out this new technology in a working Saturn Aura. You can check out my post-ride review of the technology. But right now we're going to dive in and talk about exactly what HICCI is, and how it works.
What is HCCI?
At its most basic level, HCCI combines the best properties of diesel and gasoline engines into one. Gasoline engines use spark ignition, whereas diesels are compression ignition, meaning that instead of using spark plugs to ignite the air-fuel mixture within the cylinder they use the pressure of the piston to compress the mixture, creating heat and ignition. Because compression ignition is inherently more efficient, diesel engines are predisposed to good fuel economy, but at the cost of high NOx emissions. Gasoline engines, on the other hand, are less fuel efficient, but are also much cleaner in terms of NOx emissions.