While most automakers are ready to let go of internal combustion engines for pure electric powertrains, Nissan isn't ready to do the same. It's a bold statement from them, especially since they are one of the first mainstream automakers to roll out mass-produced EVs.
The Japanese automaker wants to make engines more efficient than before, giving them a longer lease at life. And that's what they've managed to do.
In a breakthrough, Nissan announced that they built an engine with 50% thermal efficiency, further reducing CO2 emissions. For comparison, most modern gasoline engines have an average thermal efficiency rating of 40%.
However, there is a catch to Nissan's very thermal efficient engine. It won't be used to power a new vehicle alone. Instead, it mainly serves as a generator that charges up the batteries. As you may have guessed by now, the new thermally efficient motor will be in future Nissan e-Power models.
Since the engine works as a generator, it runs at a more or less constant load and RPM. As a result, Nissan tuned it to run leaner (more air, less fuel) paired with a high compression ratio. Those two alone bumped up thermal efficiency to 46%. Meanwhile, the last 4% was made up by using “waste heat recovery technologies”. Nissan hasn't explained what those are, but expect more info once the updated powertrain is released.
“In a conventional engine, there are restrictions on controlling the air-fuel mixture's dilution level to respond to changing driving loads, with several trade-offs between various operating conditions, such as in-cylinder gas flow, ignition method, and compression ratio which can sacrifice efficiency for power output. However, a dedicated engine running at an optimal range of speed and load for electrical generation makes it possible to dramatically improve thermal efficiency,” said Nissan in a press release.
So far, Nissan has only released photos of a single-cylinder mockup engine on a test bench. That said, it seems the automaker has not decided what form the engine will take. It's also a sign that the engine may be years away from production. Still, Nissan aims to be 100% carbon neutral by 2050 and plans to electrify all models by the early 2030s. The introduction of the ultra-efficient e-Power powertrain could be a great alternative for countries that lack EV infrastructure.