Japanese car maker said its cutting-edge combustion engine will be first of kind to market in 2019
Richard Bremner Autocar
23 January 2018

Mazda's new Skyactiv-X engine, which combines the spark ignition combustion of a petrol engine with the compression ignition of a diesel, “will be 20-30% more economical” than an equivalent 2.0 litre, according to the firm’s powertrain manager Eiji Nakai.

That’s significantly better than the 14% Autocar achieved in a real-world test with a Mazda prototype, but there’s more development to come before the engine is launched in 2019.

Mazda 3 Skyactiv-X 2019 prototype review: new compression ignition petrol engine driven

The Spark Controlled Compression Ignition engine will cost somewhere between the price of a conventional petrol and a diesel, said Nakai.

A number of manufacturers, including Mercedes-Benz and General Motors, have been developing compression ignition petrol engines, but Mazda believes it will be first to market. Several breakthroughs were required to enable the engine to switch from the 14.7:1 air-to-fuel mixture of a conventional petrol engine to the 29.4:1-plus lean-burn mixtures.

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One is the continuous use of spark plugs. These ignite the mixture conventionally when the engine is cold or operating at high revs but, in lean burn mode (about 80% of the time), the spark ignites a pulse of richer fuel. The resultant fireball lights the ultra-lean mixture as it’s compressed. Even and sustained burning ensues and the piston is pushed down further and longer.

The key to transitioning between spark and compression ignition lies with cylinder sensors that determine when the engine can run lean. Detection is “very difficult”, said Nakai.

The engine also uses a supercharger that pressurises intake air. In current form, the SCCI engine produces 187bhp and 143lb ft of torque.

Read more:

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Mazda 3 Skyactiv-X 2019 prototype review

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Comments
26

23 January 2018

Not a lot of torque for 187bhp.......?

Peter Cavellini.

23 January 2018
Peter Cavellini wrote:

Not a lot of torque for 187bhp.......?

I thought that too, with my remapped 1.3 Corsa diesel beating that by over 20 lbs/ft...

23 January 2018
Landie wrote:

Peter Cavellini wrote:

Not a lot of torque for 187bhp.......?

I thought that too, with my remapped 1.3 Corsa diesel beating that by over 20 lbs/ft...

If that diesel didn't have a turbo plus intercooler it wouldn't. That boost rating of that mentioned supercharger must be very low indeed. Perhaps it's more facilitating the running of the engine than boosting the power -- after all forced induction is effectively an air pump blasting more air into the cylinders, that Mazda engine presumably runs super lean mixture -- meaning, perhaps that supercharger perhaps merely in a role facilitating the basic running of that engine. 

The power and torque appear normal if we'd be talking about 2l. engine without forced induction.

23 January 2018
Peter Cavellini wrote:

Not a lot of torque for 187bhp.......?

Tones with what would be delivered by a 2l. normally aspirated engine of comparable power rating.That supercharger mentioned bust be running very very low boost.

23 January 2018
Einarbb wrote:

Peter Cavellini wrote:

Not a lot of torque for 187bhp.......?

Tones with what would be delivered by a 2l. normally aspirated engine of comparable power rating.That supercharger mentioned bust be running very very low boost.

My 320i Petrol makes 184bhp and 190 odd lb/ft...200+ with over boost for 10 secs, does 42mpg  I’m happy with that, mega mpg doesn’t interest me.

Peter Cavellini.

23 January 2018
Peter Cavellini wrote:

Einarbb wrote:

Peter Cavellini wrote:

Not a lot of torque for 187bhp.......?

Tones with what would be delivered by a 2l. normally aspirated engine of comparable power rating.That supercharger mentioned bust be running very very low boost.

My 320i Petrol makes 184bhp and 190 odd lb/ft...200+ with over boost for 10 secs, does 42mpg  I’m happy with that, mega mpg doesn’t interest me.

 

No possible way that 2l. Beamer engine is delivering 190 lb/ft. without forced induction.Without forced induction it's highly doubtful it could deliver more than close to 150lb/ft. - however usually normally aspirated 2l. doesn't go much beyond 140lb./ft.

23 January 2018
Einarbb wrote:

Peter Cavellini wrote:

Einarbb wrote:

Peter Cavellini wrote:

Not a lot of torque for 187bhp.......?

Tones with what would be delivered by a 2l. normally aspirated engine of comparable power rating.That supercharger mentioned bust be running very very low boost.

My 320i Petrol makes 184bhp and 190 odd lb/ft...200+ with over boost for 10 secs, does 42mpg  I’m happy with that, mega mpg doesn’t interest me.

 

No possible way that 2l. Beamer engine is delivering 190 lb/ft. without forced induction.Without forced induction it's highly doubtful it could deliver more than close to 150lb/ft. - however usually normally aspirated 2l. doesn't go much beyond 140lb./ft.

Drives like a bigger Engine, much improved over my previous 10’plate 2L, guess I was spun a sales pitch,,anyway it’s an impressive Engine for me.

Peter Cavellini.

24 January 2018
Not sure where they got this number in torque, but Mazdas official numbers show this 2.0L engine at 190hp with 207lbs of torque
MazdaGuy

23 January 2018

Why are Mazda bothering with the development of combustion engines? The automotive  world is going electric and the longer Mazda delay and the more they waste on this old technology, the worse will be their future. Could it really be worth the investment for the last few years in which engines will be permitted?

Robbo

Aussie Rob - a view from down under

23 January 2018
Aussierob wrote:

Why are Mazda bothering with the development of combustion engines? The automotive  world is going electric and the longer Mazda delay and the more they waste on this old technology, the worse will be their future. Could it really be worth the investment for the last few years in which engines will be permitted?

Robbo

We probably have quite a long time before electric cars are able to fully replace petrol/diesel so surely any and all advancements that reduce consumption and emissions should be welcomed, plus I would have thought the most economical petrol engine mated to a hybrid system would be a great idea, maybe that will be next?

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