Mazda reveals radical new petrol engine that doesn't need spark plugs and is 30% more efficient than current cars

• Engine uses compression instead of spark to ignite fuel, making it more efficient
• Car firms have spent decades trying to perfect the compression engine system
• Mazda says it will start selling cars using the new Skyactiv-X engine in 2019
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Mazda Motor Corp said it would become the world's first automaker to commercialize a petrol engine using technology that deep-pocketed rivals have been trying to engineer for decades, a twist in an industry that is increasingly going electric.

The Japanese automaker, with a research and development budget a fraction of those of major peers, plans to sell cars from 2019 with compression ignition engines - a type of cleaner, more fuel efficient petrol engine that has eluded the likes of Daimler AG and General Motors Co.

'It's a major breakthrough,' said Ryoji Miyashita, chairman of automotive engineering company AEMSS Inc.

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Mazda Motor President Masamichi Kogai revealed the engine and said the first hopes to introduce it in 2019. It has called its engine SKYACTIV-X, and said it would be 20 to 30 percent more efficient than its current SKYACTIV-G

The announcement places traditional engines at the centre of Mazda's strategy and comes just days after Mazda said it will work with Toyota Motor Corp to develop electric vehicles.

'We think it is an imperative and fundamental job for us to pursue the ideal internal combustion engine,' Mazda R&D head Kiyoshi Fujiwara told reporters. 

'Electrification is necessary but... the internal combustion engine should come first.'

A homogeneous charge compression ignition (HCCI) engine ignites petrol through compression, eliminating spark plugs. 

Its fuel economy potentially matches that of a diesel engine without high emissions of nitrogen oxides or sooty particulates.

Mazda's engine employs spark plugs under certain conditions, such as at low temperatures, to overcome technical hurdles that have hampered commercialization of the technology.

HOW IT WORKS

A homogeneous charge compression ignition (HCCI) engine ignites petrol through compression, eliminating spark plugs. 

Its fuel economy potentially matches that of a diesel engine without high emissions of nitrogen oxides or sooty particulates.

Mazda's engine employs spark plugs under certain conditions, such as at low temperatures, to overcome technical hurdles that have hampered commercialization of the technology.

To keep the temperature low at compression, the system reduces the amount of hot exhaust gas inside the combustion chamber.

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To keep the temperature low at compression, the system reduces the amount of hot exhaust gas inside the combustion chamber using a 4-2-1 exhaust system 

In the Skyactiv-G, for example – the predecessor to the Skyactiv-X – Mazda uses a 4-2-1 exhaust system.

This relies on a pipe with a length over 600mm to elevate actual-use torque, and a loop shape to save space.

As the long distance cools the exhaust gas before it reaches the catalyst, which would then delay the catalyst’s activation, the system delays ignition timing after engine-start for stable combustion.

A piston cavity is used to optimize fuel injection further, to formulate a stratified air-fuel mixture around the spark plug, according to Mazda.Executive Vice President Akira Marumoto called Mazda's engine technology the automaker's 'heart'.

It has called its engine SKYACTIV-X, and said it would be 20 to 30 percent more efficient than its current SKYACTIV-G. 

It has no plans to supply the engine to other carmakers, Marumoto said.

AEMSS' Miyashita said a key issue is how smooth and responsive the engine is.

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It has called its engine SKYACTIV-X, and said it would be 20 to 30 percent more efficient than its current SKYACTIV-G (pictured)

'Is it jerky? If so, that would pose a big question when it comes to commercializing this technology.' he said. 

'Hopefully Mazda has an answer to that question.'

Mazda also said it would introduce electric vehicles and electric technology in its cars from 2019, focusing on markets that restrict the sale of certain vehicles to limit air pollution or that provide clean sources of electricity.

In addition, it said it aimed to make autonomous-driving technology standard in all of its models by 2025.