The Japanese automaker Mazda is working on the development of a new SKYACTIV-G engine, which will allow the petrol-powered engines to work on the same principle like diesel engines and to consume up to 30% less.
Mazda is already working on the next generation of SKYACTIV-G petrol engines that promise to revolutionize the engines of this type. The new engines are expected to debut in 2017 and could have an atypically high compression ratio of 18.0:1, while the current SKYACTIV-G engine has a 14.0:1 ratio. For comparison, most modern otto engines used for cars have a compression ratio located between 10.0:1 and 12.0:1.
2017 Mazda SKYACTIV-G petrol engine – The Specs
As if the high compression ratio of these engines was not an impressive feature enough, Mazda will apply a different solution for igniting the fuel mixture: compression, “reserved” in terms of technology for diesel fueled engines, at least until now. Changing the functioning mode of the engine will only operate at partial loads and possibly at idling speed.
The technical solution of Mazda is called, in short, HCCI, and was investigated by auto manufacturers such as Mercedes-Benz, Hyundai / Kia and General Motors. The HCCI acronym means Homogenous Charge Compression Ignition.
Basically, it means that this technology will use the temperature and pressure from the combustion chamber to ignite the fuel, all without the spark normally used by the petrol engines – known in the technical literature as ” Spark-ignition engine.” Mazda say that their new technical solution is more efficient than small displacement turbocharged engines, an aspirated engine being almost 30% more economical thanks to this technology, as shown in the internal tests.
“We decided not to follow the downsizing approach because our SKYACTIV engines will be competitive without that,” said the general manager of Mazda’s product strategy division, Hidetoshi Kudo, at a Mazda technology forum in Yokohama.
Indeed, Ichiro Hirose, the vice-president of Mazda’s European R&D Centre, said Mazda would not be able to meet future emissions laws without HCCI, which more effectively reduces fuel consumption in the real world compared to downsized engines.
“In order to improve efficiency we have no choice but to go to HCCI,” he said. “The aim is to get another 30 per cent in thermal efficiency with HCCI.
“This statement is not based on a wish but based on many tests already in our research activity.
“We’re going to build the ideal internal combustion engine, with vastly reduced well-to-wheel CO2 emissions. [We can achieve] hybrid-like fuel consumption with HCCI in the second-generation.”
HCCI: the anti-downsizing solution
HCCI technology will allow compression ratios between 16:1 and 18:1 to work with as little fuel needed without suffering detonations, pre-ignition or other irregularities in the operation of the engine and friction losses will be reduced by 20%. Harmful emissions of NOx, ie various nitrogen oxides will be reduced dramatically, as will be the pumping losses.
In total, all the changes implemented will reduce fuel consumption by 30% compared to the current SKYACTIV-G engines. The main challenges of the new technologies are represented by the transition from compression ignition to spark ignition, the diesel engine functioning being incompatible with high engine revolutions of the petrol engines and changing the type of ignition is difficult to achieve in a uniform manner.
The third-generation Mazda SKYACTIV-G engines
The third-generation SKYACTIV-G engines from Mazda, prepared after the new units release scheduled on 2017, also will implement the adiabatic combustion chamber. This involves a process that takes place without transfer of heat or matter between a system and the surrounding environment. The challenges of the new technology, close to those of SKYACTIV-G II, include managing heat losses, a performance problem for the current internal combustion engines.
Mazda SKYACTIV-G III via Mazda