Mazda claims its next-generation SKYACTIV-X is as eco-friendly as current electric vehicles.
14 Mar 2018 | 5807 Views | By Autocar Pro News Desk
Mazda is claiming that its new SKYACTIV-X engine can reduce emissions from an internal combustion engine to a level below that of an electric vehicle when measured from ‘well-to-wheel’.
The Japanese automaker says it is bettering the real-world emissions of EVs by maximising the efficiency of the internal combustion ...
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Mazda is claiming that its new SKYACTIV-X engine can reduce emissions from an internal combustion engine to a level below that of an electric vehicle when measured from ‘well-to-wheel’.
The Japanese automaker says it is bettering the real-world emissions of EVs by maximising the efficiency of the internal combustion engine through its next-generation SKYACTIV-X petrol engine.
In order to more correctly measure CO2 emissions over the lifecycle of a vehicle, Mazda is moving beyond current 'Tank-to-Wheel' evaluations (which consider only emissions whilst driving), to a 'Well-to-Wheel' method, which also considers fuel extraction, manufacturing and shipping.
How SKYACTIV-X makes it possible?
Mazda’s new SKYACTIV-X engine comes with the world’s first commercial petrol engine to use compression ignition, where the fuel-air mixture ignites spontaneously when compressed by the piston.
The company’s proprietary combustion method – Spark Controlled Compression Ignition (SPCCI) – combines the spark ignition of a petrol engine with the compression ignition of a diesel. This maximises the operating zone in which the compression ignition is possible and achieves a seamless transition between compression ignition and spark ignition.
SPCCI gives the engine the ability to switch from the ideal stoichiometric 14.7:1 air-to-fuel mixture of a conventional petrol engine to the lean-burn mixture of 29.4:1. This also enables the spark plugs to ignite the mixture in a conventional manner even when the engine is cold or running at high revs.
When the engine is in lean-burn mode -- about 80 percent of the time -- the spark plugs ignite a pulse of fuel-rich mixture injected into the centre of the cylinders under ultra-high pressure during the compression stroke. This, in turn, provokes compression ignition in the pressure and even lets it burn, leading to a more powerful piston stroke. The combustion timing is controlled by the flame from the spark plug.
Hence, SPCCI combines the advantages of both petrol and diesel engines to achieve outstanding environmental performance, power and acceleration. Combined with a supercharger to boost intake pressure, compression ignition delivers unprecedented engine response and an increase in torque of 10-30 percent over the current SKYACTIV-G petrol engine, whilst the super lean-burn improves engine efficiency by up to 20-30 percent over the current SKYACTYIV-G. Moreover, SKYACTIV-X is said to even equal or exceed the latest SKYACTIV-D diesel engine in fuel efficiency.
Mazda's reasoning for being on par with EVs
A mid-sized electric car consumes around 20 kilowatt-hours of electricity per 100km. Production of this power with coal translates into CO2 emissions of 200g/km; with petroleum, 156g/km; and with LNG (liquefied petroleum gas), 100g/km. When converted to a 'Well-to-Wheel' figure, then, the average CO2 emissions of an EV are some 128g/km, depending on the power generation source, whilst that of a Mazda SKYACTIV-G petrol engine of comparable power is 142g/km. This means that with as little as a 10% improvement in efficiency, SKYACTIV-G engine emissions will be on par with those of electric vehicles.
Mazda’s SKYACTIV-X has won multiple awards across the globe, like the Quattroruote Global Tech Award and the FuturAuto 2018 Trophy for Automotive Innovation.
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