Mazda remains one of the few automotive manufacturers still publicly committed to the internal combustion engine, despite the trend towards electrification.
With that in mind, it's working to extract every last drop of potential from bang-suck-blow engines. The company says its next generation of SkyActiv engines will be able to extract at least an additional 30 per cent thermal efficiency over the just-launched SkyActiv X engine.
Speaking to CarAdvice at the Geneva motor show, Ichiro Hirose, the company’s managing executive officer of powertrain development said he's aiming for peak efficiency from internal combustion in the next generation.
“If we call this SkyActiv series generation two and the next generation three, and if you compare it with SkyActiv X engine that we have so far, there is a potential 30 per cent more improvement in thermal efficiency,” Hirose said.
“We are already endeavouring technical development that will allow us to reach that goal. If you go to a textbook for engineers about engine efficiency there are only two factors that we have to consider for improving thermal efficiency," he continued.
"One is improving compression ratio and second is increasing the specific heat ratio, meaning that trying to combust in a lean situation as much as possible.”
According to Hirose, the generation-one SkyActiv engines improved on compression ratio, the soon-to-be-launched generation-two (dubbed X) improved heat ratio, and the third generation will push all boundaries further as Mazda looks to "limit and suppress the heat loss that you can get, which means that if you can suppress heat loss you can increase compression ratio even further".
"If we take the current architecture that is available to us and try and raise the compression ratio, even more, you can see that the air-fuel mixture is going under severe compression but that leads to heat generation, and that is being lost in the combustion chamber walls with the current architecture," he went on.
"If we can limit the heat loss through the chamber walls that means that we can increase compression ratio even more which means increased efficiency.”
That seems to also apply to future SkyActiv diesel engines, although they've actually dropped their compression ratio recently due to NOX emission requirements. Mazda expects its next generation of engines to be the peak of efficiency and, if that's the case, likely the last major update to the internal combustion before it pushes hard into EVs.
“We believe that even in 2030 the ICE will remain and that’s the basis for why we are continuing," Hirose explained.
"And we mention that for petrol engine we are looking into generation three, It sounds like a stepwise development but in actual fact, it continues development and then we release it in a stepwise fashion.
"If we are not able to achieve ultimate level efficiency by generation three then we will look into generation four [but] we set ourselves the goal that we want the ultimate combustion by generation three.”