Mazda compression ignition engine breakthrough

Mazda claims 30% economy boost with 'breakthrough' Skyactiv-X tech

Japanese car maker said its cutting-edge combustion engine will be first of kind to market in 2019

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.

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.

Mazda Skyactiv-X engine range to gain plug-in hybrid variant from 2021

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.

https://www.autocar.co.uk/car-news/...30-economy-boost-breakthrough-skyactiv-x-tech
 
Mazda: 2019 Skyactiv-X engine can boost economy by 30%

Autocar samples lean burn compression ignition engine that promises greatly improved efficiency

Mazda will put a new version of its 2.0-litre Skyactiv-X engine into production next year with the promise of up to 30% improvement in fuel consumption over the existing Skyactiv-G petrol.

That figure is said to be possible during low-speed driving, but the company claims that 20% is also possible in average real world driving scenarios. The target outputs for when the engine hits the market in 2019 is 187bhp and 170lb ft.

Development engines have been installed in six prototype cars comprising Mazda 3 bodies underpinned by the new Skyactiv architecture. The new Skyactiv-X engine relies on two technologies – lean burn combustion and compression ignition – to reduce fuel consumption and CO2 emissions while delivering good performance.

A conventional internal combustion engine mixes air with fuel at a ratio of 14.7:1, the perfect mixture to burn petrol in the cleanest possible way. Fuel is ignited by a spark inside the engine’s combustion chamber and burns progressively until it is used up in a split second. A leaner mixture can improve economy, but can be more difficult to ignite and leads to faltering combustion.

The Skyactiv-X technology successfully sidesteps those problems with spark-controlled compression ignition (SPCCI), which reliably ignites the entire lean air/fuel mixture of between 30:1 and 40:1 in one go. Extra air to feed the lean burn running is supplied by a small, belt-driven, Rootes-type air pump.

A higher-than-normal compression ratio of 16:1 produces almost enough pressure to combust the lean fuel-air mixture spontaneously, but not quite. That happens when a second dose of fuel is injected and fired by a spark to create a mini fireball. The extra pressure created by the fireball tips the simmering main charge over the edge and it ignites.

The engine can run in this mode throughout a large part of the operating range but, when the driver accelerates very hard, the engine switches to a conventional mode burning a spark-ignited 14.7:1 air fuel mixture like any other petrol internal combustion engine.

SPCCI is an evolution of a concept called HCCI (homogeneous charge compression ignition), which a number of manufacturers tried but failed to perfect more than a decade ago. The main problem was switching between HCCI mode and conventional mode, now solved by Mazda with SPCCI.

The new Skyactiv vehicle architecture is lighter to improve energy efficiency. It is also aimed at improving driver control by giving a smoother ride by reducing road shocks into the cabin. A stiffer structure using more lightweight steel components helps improve handling and ride, and the introduction of thimble-sized structures called ‘damping nodes’ at crucial joints reduces noise and vibration in the cabin.

This engine’s recent reveal was accompanied by a second look at the Kai concept first shown at the Tokyo motor show last year. The Kai’s clean lines are designed to exploit the light falling on the car’s surfaces and hint at how the next Mazda 3, based on the Skyactiv architecture, could look.

What's a Mazda 3 Skyactiv-X prototype like to drive?

The Skyactiv-X engine has been substantially improved since Autocar tried an early prototype last year.

Driven back to back with a current Mazda 3 on a variety of Portuguese roads in both manual and automatic form, the prototype proved surprisingly refined. There was an absence of combustion noise and, if anything, the engine was smoother and quieter than the production Mazda 3.

Engineers say the new architecture contributes to the smooth drive with improved isolation from powertrain and road noise.

A screen displayed three green discs to indicate which mode the engine was running in – conventional, lean burn mode or ultra-lean mode. Lean mode was achievable most of the time on both motorways and country roads, and the engine would quite often switch to the most frugal, ultra-lean mode when cruising at a steady speed.

When it goes on sale, the new engine will be subject to the new WLTP test cycle so quoted figures should give an accurate indication of what buyers can expect in terms of economy and CO2 emissions.

https://www.autocar.co.uk/car-news/new-cars/mazda-2019-skyactiv-x-engine-can-boost-economy-30

Skyactiv-X 1.jpg
Skyactiv-X 2.jpg
Skyactiv-X 3.jpg
Skyactiv-X 4.jpg
 
Mazda plans straight-six Skyactiv-X petrol and diesel engines

Japanese brand to develop inline-six engines with compression ignition tech, financial presentation reveals

Mazda is lining up a range of compression ignition straight-six engines, both petrol and diesel, as part of its anti-downsizing initiative.

The plans were revealed in a financial year results report, compiled last month and published on Mazda’s global site before apparently being removed after media outlets spotted the plans.

A slide from the report, below, lists ‘Straight-six Skyactiv-X engine’ and ‘Straight-six Skyactiv-D (2nd-generation Diesel engine)’ as two of its product investments for the future, alongside electric vehicles and hybrids.

The two engines are listed under the branch of ‘Large Architecture’ - likely relating to the size of platform and body they will be mated to. Such a reference, alongside the development of engines (particularly a straight-six diesel) that almost exclusively sit in larger, premium-brand models in Europe, suggests that Mazda may expand its upper tier of future product offering to compete with Audi, BMW and Mercedes.

https://www.autocar.co.uk/car-news/...ight-six-skyactiv-x-petrol-and-diesel-engines
 
Mazda confirms new inline-six engines, hints at RWD platform

Mazda has confirmed it plans to build inline-six petrol and diesel engines, while also hinting it will develop a new rear-wheel-drive platform for large vehicles.

As pointed out by the folks over at Jalopnik, the Japanese company included a rather interesting page (embedded below) its Fiscal Year March 2019 Financial Results document.

It shows Mazda plans to further mature its so-called Kodo design language, as well as upgrade its current four-cylinder engines, offer a mild-hybrid powertrain and add an "independently developed" electric vehicle to its small car stable.

The document furthermore lists plans to build straight-six engines (in Skyactiv-X and Skyactiv-D guises) for a new large vehicle platform (fresh Mazda6, anyone?) set to employ a longitudinal engine layout. Of course, the latter suggests rear-wheel drive, although the firm states it will also include all-wheel drive. A 48-volt mild hybrid and plug-in hybrid arrangements are seemingly also on the cards.

https://www.carmag.co.za/news/mazda-confirms-new-inline-six-engines-hints-at-rwd-platform/
 
Mazda Plans Straight-6 Engines

While the world continues on its downsizing of engines course, Mazda is busy preparing a new generation of big straight-6 engines. Here's what we know so far.

Mazda has confirmed it'll be assembling a new family of straight-6 petrol and diesel engines for future products. Dubbed Skyactiv-X, these new engines will be joining an all-new platform with the capacity for rear-wheel drive as well as all-wheel drive. There'll also be hybrid and plug-in hybrid capacity.

https://www.cars.co.za/motoring_news/mazda-plans-straight-6-engines/46652/
 
It would be very interesting to see the reliability of the SPCCI engine, for compression ignition, it is difficult to control the detonation progression in order not to have knocking.
 
it might be a the return of the cast iron engine block with proper forged pistons.

all hail the 2jz gte
 
You must log in or register to reply here.
Back
Top
Sign up to the MyBroadband newsletter
X