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IRVINE, Calif. – A minor fleet of well-worn, matte-black Mazda3'due south here acquit an amazing new technology nether the hood, called SkyActiv-X: They utilise gasoline, only compress the fuel and then much it spontaneously combusts like a diesel engine. The efficiency gains could corporeality to 20 percent, possibly thirty per centum more than than the same engine burning gasoline in the traditional way, Mazda believes.

A test drive shows Mazda's SkyActiv-Ten engineering science indeed works and should be available in 2019. The compact sport hatchback prototypes showed solid power under dispatch. Noise levels were adequate thanks to lots of audio-damping material, including around the engine. And with SkyActiv-X, at that place should be none of the diesel-fuel pollution concerns.

With a traditional gasoline engine, combustion starts when the spark plug fires. With a diesel information technology'southward when fuel is injected. With a homogenous charge compression ignition (HCCI), combustion when heat and force per unit area are high. HCCI is 1 of two Mazda SkyActiv-10 modes. (Source: Mazda)

How SkyActiv-X Works: Homogeneous Charge Compression

The SkyActiv-X engine works in two means, or modes: one just similar a diesel engine, except it's using gasoline that is compressed and cocky-ignites; and i similar a diesel with a lean fuel-air mixture load that needs a slight boost from a spark plug to raise the temperature and pressure to the point where the lean mixture lights off. The pinch ratio is xvi:one.

This first mode is is homogeneous charge compression ignition, or HCCI. Other automakers have worked on this for years, with varying express degrees of success. Frequently they utilize lean air/fuel mixtures. Were HCCI the but technology used, it would be challenging to map and implement the necessary air/fuel mixtures against temperatures within the cylinders, octane rating, and other factors. HCCI is besides challenged past loftier engine speeds (rpm) and hard acceleration (something Mazda drivers enjoy). Mazda realized HCCI couldn't be the only engine mode. But it could be an important part of the SkyActiv-Ten ecosystem.

With spark controlled compression ignition, a lean fuel-air mixture won't ignite by pressure level alone. A spark sets a a fireball that further heats and pressurizes the cylinder, resulting in compression ignition in the rest of the cylinder. (Mazda)

How SkyActiv-Ten Works II: Spark Boosts Compression Ignition

A second manner is spark [plug] controlled compression ignition, or SPCCI. The machine automatically shifts to SPCCI ignition when there's more load than HCCI tin handle. With SPCC, there'due south a spark plug involved but, says Mazda, the spark only indirectly causes ignition. (If it directly ignited the entire fuel/air mix, information technology'd only be a high-compression gasoline engine.) Additional air is pumped into the cylinder via what Mazda calls a supercharger, although it's merely pumping in more air to create a leaner fuel/air mix, meaning more air than the 14.7:1 stoichiometric ratio of air to fuel.

SkyActiv-10 mixes air and fuel during the the intake stroke of the cylinder, keeping it just below the level of self-ignition, which is a constantly changing target depending on cylinder temperature, gasoline octane rating, and air/fuel ratio. Just equally the piston completes the compression stroke and is about to starting time the downward power stroke, the high-force per unit area fuel injector adds a trace more fuel and the spark plug immediately sets information technology alight. That raises the temperature and cylinder pressure plenty to prepare fire to the primary air/fuel mixture and accomplish a complete fire, so there's no soot exhausted. Then the spark plug does not directly ignite the bulk of the air/fuel mix.

More than Ability, Greater Economy

The 2018 Mazda3 sold today generates 155 hp, produces 150 lb-ft of torque, and gets 37 mpg in highway driving from its 2.0-liter SkyActiv-Thousand four-cylinder engine with a xiii.0:1 compression ratio on regular gasoline (yes, that's an amazingly high compression ratio already).

If Mazda'southward goals of 20 percent, possible thirty percent, improvements happen, that would mean a 2.0-liter SkyActiv-X engine generates 186-202 hp, 180-195 lb-ft of torque, and 44-48 highway mpg. That's excellent for a motorcar without the turbocharging that rams in more than fuel and air. Mazda pegs the SkyActiv-Ten engine now being tested at 178 hp and 170 lb-ft of torque.

SkyActiv-10 is part of Mazda'due south Sustainable Zoom-Zoom 2030 project covering safety and the environment. Compared with a 2010 baseline, Mazda plans to reduce well-to-wheel CO2 emissions (a proxy for fuel consumption) past 50 percent in 2030 and by 90 percent in 2050. Because of the slow credence rate of hybrids, plug-ins, and pure EVs in the United states of america currently (most 2 percent of all sales/leases), Mazda sees greater near-term gains from making gasoline and diesel engines more efficient. Thus SkyActiv-D (diesel), SkyActiv-G (gasoline) and SkyActiv-Ten (HCCI / SPCCI gasoline diesel).

Audio-damping material surrounds the engine. Annotation gasket in front of engineer's correct hand. Doors have double seals.

Improve Seats, More Racket Insulation

Next-generation seats help comfort, combat slouch.

Diesels have been inherently noisy and rough. Information technology'south only in the by 5-10 years has it been difficult to tell from the within that you're in a diesel automobile. Mazda is working even harder to eliminate signs of roughness of the SkyActiv-X vehicles. There is considerable sound-damping material in the test mules.

Separately, Mazda is developing seats for next-generation cars that don't pb to slouched seating (photo) and using high-density cream to absorb engine and ride vibration. These are what you lot'd discover on an Audi-level vehicle, but then Mazda's other goal is to evangelize premium cars at mainstream pricing and the CX-9 and CX-5 crossovers are promising early on examples. Mazda is besides reworking the commuter's seat vs. pedal placement and then the 2 or three foot pedals are directly in forepart of the driver, not angled off-middle.

In our test drives in and effectually littoral southern California, the cars were reasonably well mannered. The power ring was wide, which suggests Mazda might behave the half dozen-speed automatic over to production, without demand to crash-land up to eight or more speeds. (There was as well a half-dozen-speed manual test car, and a manual should be in Mazda'due south plans for SkyActiv-10.) Those who tromped hard on the throttle were greeted with occasional clatter. Diesels are oft noisiest when they're cold and the examination cars I stepped into were already running and ready to drive.

Mazda timeline has SkyActiv-X arriving in calendar year 2019, starting time hybrids and EVs 2019, and a second-generation Skyactiv diesel fuel in 2020 (United states still awaits the first-gen). ICE is internal combustion engine, i-ActivSense includes commuter assists and democratic driving. The SkyActiv-X diesel fuel volition be in a new body. Kodo is Mazda's blueprint language of the car every bit a living/moving affair, creating a bail between driver and motorcar, or "horse and rider as 1 [jinba ittai]."

SkyActiv-X: Run across Y'all in 2019?

Mazda is aiming SkyActiv-10 for the 2019 calendar year in what would be a new chassis, almost probable besides the quaternary generation of the Mazda3. The Mazda3 is currently Mazda's second best seller later on the CX-v, with 75,018 sold in 2017 and just under 100,000 the year before.

At the aforementioned fourth dimension, Mazda continues its goal of wringing more than power and/or efficiency of near every component and has been for the nearly of the concluding decade. They include 15 percent from the 2001-era MZR "MaZda Responsive" gas engines to the electric current SkyActiv-One thousand, 20 percent from MZR-CD (diesel) to Skyactiv-D; 1 percent on transmission transmissions and four-7 percentage on SkyActiv Drive automatics; iii-5 percent on 100 kg (220 pounds) of weight reduction.

The production SkyActiv-X would become a mild hybrid electrical motor also. Most probable it would exist a 48-volt system which allows for a pocket-sized lithium-ion battery and meaty packaging, although Mazda declined to annotate.

Mazda already has the industry's best overall fuel economy (and has for five directly years), reaching 29.half dozen miles per gallon overall for the 2016 yr. SkyActiv-X and SkyActiv-D (diesel fuel) will but aid. With the SkyActiv-X, it'due south all the more amazing coming from i of the industry'southward smallest automakers. Although pocket-sized may be an reward, says Mazda vehicle development engineer Dave Coleman: "If the engineer needs to make a change, he may be sitting right next to the person who can make it happen."