Mazda took the industry by storm when earlier this month it announced plans to introduce gasoline-powered Homogeneous Charge Compression Ignition (HCCI) engines in 2019.
HCCI engines are typically referred to as the holy grail of internal-combustion engine technology since they're extremely efficient and promise low emissions.
Who better to explain how the technology works than Jason Fenske of Engineering Explained? Thankfully, he's tackled the topic of the gasoline HCCI engine and explained how Mazda plans to solve some of the potential drawbacks that come with the technology.
HCCI engines work by using compression to ignite the air and fuel mixture, just like in a diesel. Normally in a gas engine, you use a spark plug for the ignition. HCCI is prevalent with diesel-powered engines, but gasoline has been a tough cookie to crack since a specific temperature is the one factor that must be present in order for the air-fuel mix to combust. If the engine is too hot, engine knock and unpredictable timing is present; if it's too cold, ignition problems ensue.
So, Mazda looked to the past and found a solution: use a spark plug. Like a traditional gas engine, Mazda's HCCI engine uses a spark plug to ignite the air and fuel mixture should ambient temperatures be too low, if the engine is subject to a cold start, and during high-rpm driving situations.
Any times the temperature is conducive to HCCI, that technology takes over. For example, when the car is cruising at a constant speed on the highway or during low-load situations around town. Mazda has said its HCCI engine, known as Skyactiv-X, will be 20- to 30-percent more efficient than its current crop of powertrains. In addition, Mazda has also said its family of HCCI engines will also be supercharged—power when it's needed, and incredible efficiency at all other times. Mazda may have truly given internal-combustion engines a new lease on life.
What still isn't known is what car we'll first see the HCCI engine make its debut. The current thinking is a redesigned Mazda 3.