Skyactiv (branded as SKYACTIV) is a brand name for a series of technologies developed by Mazda that increase fuel efficiency and engine output. The initial announcement of the Skyactiv technologies included new engines, transmissions, body, and chassis, which appeared in Mazda products from 2011 onwards.[1][2][3]
The precursor of Skyactiv, which featured a Mazda Sky-G 2.3-liter direct injection gas engine, a Mazda Sky-D 2.2-liter diesel engine, a Sky-Drive automatic transmission, a Mazda Kiyora with Sky-G 1.3 engine and Sky-Drive automatic transmission, was unveiled at the 40th Tokyo Motor Show in 2008.[4][5] The Skyactiv concept features a revised suspension geometry, improved automatic and manual transmission, and various improvements to Mazda's L- engine such as direct injection, upgraded exhaust manifold, increased compression ratio for cleaner burn and higher thermal efficiency, etc. Mazda's previous chassis for the Mazda 3 and Mazda 6 were carried over to the new vehicles.
The Skyactiv-G or formerly Sky-G[6] is a family of direct injection petrol engines. The engine compression ratio is increased to 14.0:1. To reduce the risk of engine knock at high compression, residual gas is reduced by using 4-2-1 engine exhaust systems, implementing a piston cavity, and optimizing fuel injection. In addition, combustion duration is shortened by intensifying air flow, increasing injection pressure, and using multi-hole injectors.
It features an all-aluminum construction with chain-driven dual overhead camshafts with VVT and gasoline direct injection; with direct ignition, it meets ULEV emission standards. Skyactiv-G engines for the U.S. market have a lower compression ratio of 13:1 allowing them to operate on standard instead of premium fuel with an approximate 3-5 percent reduction in torque and fuel economy.[7]
1.3 l
The Skyactiv-G 1.3 (P3-VPS) is a variant with 1,298cc (79.2cuin) engine displacement and features a 71.0mm (2.80in) bore and an 82.0mm (3.23in) stroke. The engine was unveiled at the 2011 Automotive Engineering Exposition.[8][9]
Five Mazda engineers were awarded the 2011 Japan Society of Mechanical Engineers Medal on April 20, 2012 specifically for the "development of a petrol engine (1.3 L) with a super-high compression ratio and achieving fuel efficiency of 30 km per litre (under Japan's 10-15 cycle)".[10] The engine was first used in the Mazda2 1.3-Skyactiv.[11][12]
The Skyactiv-G 1.5, or (PR-VP RS) for RWD applications and (P5 VPS F-P5) for FWD applications, is a 1,496cc (91.3cuin) engine with a 74.5mm (2.93in) bore and an 85.8mm (3.38in) stroke.
This 4 cylinder engine was introduced in the 14MY Mazda3 for the Asian and European markets, it develops 85kW (114hp) at 6,000 rpm and 111lb⋅ft (150N⋅m) of torque at 4,000 rpm (Asia Markets). This new petrol engine added to the Skyactiv line-up achieves a high compression ratio of 13.0:1 (14.0:1 in some markets). It greatly improves dynamic performance and fuel economy over the MZR 1.5 engine of the previous model.
The Skyactiv-G 2.0 or (PE-VPS) was the first engine in the Skyactiv-G family to be produced.
This engine features an engine displacement of 1,998cc (2.0L; 121.9cuin), with a bore X stroke of 83.5mm ×91.2mm (3.29in ×3.59in). The U.S. version has a compression ratio of 13.0:1 producing 155bhp (157PS; 116kW) at 6000 rpm and 200N⋅m (148lbf⋅ft) of torque at 4600 rpm.[14] In some markets, the 162bhp (164PS; 121kW) and 210N⋅m (155lbf⋅ft) of torque with Flexifuel E85 is available.
According to Mazda, it is more fuel efficient than the engine it replaces. Versus the engine in the 2011 Mazda3 (with an automatic transmission), they improved fuel economy from 10.2l/100km (23mpg‑US) to 8.4l/100km (28mpg‑US) in town, and from 7.1l/100km (33mpg‑US) to 5.8l/100km (41mpg‑US) on the highway compared to the 2011 model.[15]
The MX-5 ND2 2019 facelift received an updated engine producing 181bhp (184PS; 135kW) with maximum RPM raised from 6800 to 7500 rpm and includes a larger intake manifold, increased injection pressure and a new exhaust system that scavenges the cylinders quicker.[16]
The Skyactiv-G 2.5 or (PY-VPS) is a 2,488cc (151.8cuin) engine first used in the 2013 Mazda 6 and features an 89.0mm (3.50in) bore and a 100.0mm (3.94in) stroke.
The U.S. version with a 13.0:1 compression ratio produces 187hp (139kW) at 6,000 rpm and 252N⋅m (186lb⋅ft) of torque at 4,000 rpm.[17]
Naturally-aspirated Skyactiv-G 2.5 engines manufactured from 2018 onwards feature cylinder deactivation to improve fuel efficiency.[18] In July 2019, approximately 262,000 Mazda vehicles using the engine were recalled for a faulty powertrain control module that may cause a misfire or a loss in power.[19]
The turbocharged version or (PY-VPTS) operates with a 10.5:1 compression ratio,[20] and produces 250hp (190kW) and 430N⋅m (320lb⋅ft).
Skyactiv-X is the first commercial petrol engine to use homogeneous charge compression ignition (HCCI), in which the fuel-air mixture ignites spontaneously when compressed by the piston. This allows it to reach a compression ratio of 16:1 instead of 14.0:1 of previous generation and operate much leaner than a spark ignition engine, reducing fuel consumption and emissions.[21][22]
This engine targets 20-30% greater fuel efficiency by utilising HCCI technology. In order to handle ignition problems caused by compression ignition, each cylinder also incorporates a spark plug featuring Spark Controlled Compression Ignition (SPCCI) technology.[23] A small Roots-type supercharger further expands the compression ignition operating window by feeding more air into the engine, leaning out the mixture sufficiently for compression ignition even at higher speeds. [24]
SPCCI works by drawing in a lean, homogenous air-fuel mixture, it then compresses the mixture until it approaches the point at which it would spontaneously detonate. A second injector then adds a secondary charge of fuel directly on the spark plug. This secondary charge is ignited by the spark plug, causing the cylinder pressure to very quickly rise to a point where the rest of the fuel undergoes compression ignition. The presence of the spark plug allows the engine to also operate as a spark-ignition engine under some operating conditions, such as high-speed high-load situations. Revealed June 5, 2019, the output is 132kW (177hp) and 224N⋅m (165lbf⋅ft).[23]
Mazda is developing an inline-six variant of the Skyactiv-X, with displacements of 3.0 and 3.3 liters and a rear-wheel-drive layout. Production of the new engine will begin in 2022 with the fourth generation Mazda6 and a new RWD crossover SUV.[25][26]
Skyactiv-D is a family of turbocharged diesel engines, designed to comply with global emissions regulations.
To eliminate the need of NOx and particulate treatment in contemporary diesel engines, the cylinder compression ratio is reduced to 14.0:1. Cold engine start is achieved via multi-hole piezo injectors with 3 programmable injection patterns, and adoption of ceramic glow plugs. Engine misfiring is prevented via variable valve lift at exhaust, which opens exhaust valves during the intake stroke, which increases engine air temperature. The Skyactiv-D also uses a two-stage turbocharger, in which one small and one large turbo are selectively operated, according to driving conditions.
S5-DPTS/S5-DPTR
Also known for Skyactiv-D 1.5 (1,499cc (91.5cuin)) engine was first introduced in the fourth generation Mazda Demio/Mazda2. It features a compression ratio of 14:1.[27]
Also known for Skyactiv-D 2.2 (2,191cc (133.7cuin)) engine is the first Skyactiv-D engine used in production vehicles. It was first used in the Mazda CX-5.[29][30] In the Mazda6, it produces 129kW (173hp) and 420N⋅m (310lb⋅ft).[31] An upgraded version of the Skyactiv-D was run in the 2013 Rolex Sports Car Series season and helped Mazda win the GX manufacturer's championship. The engine is slated to be used again in two Lola LMP2s in the United SportsCar Series.
Unique technology
The Skyactiv-D is the first low compression diesel in a production car, having a significantly lower compression in the first generation of 14:1 rather than higher compression ratios of 16:1 and higher.[32] Numerous university studies have investigated the benefits of low compression diesel for decades, with the major benefit noted in single cylinder university tests of being a drastic reduction in NOx emissions, while also reducing particulate matter and combustion noise.[33][34] These studies all concluded that while there were noticeable reductions in emissions, this came at the expense of difficult cold starts. Mazda resolved this in the Skyactitv-D by using piezoelectric fuel injectors with multiple nozzles that changes the pattern depending on operating conditions. Furthermore, exhaust valves are left slightly open as the engine starts causing exhaust gases to be sucked into the cylinders helping the engine to warm up quickly.[32]
Early issues
The CX-5 with Skyactiv-D engines were reported to have oil levels rising earlier than expected upon release, which required owners to check the vehicle's engine oil every 1000 kilometres or every month and return to the dealer if the oil appeared over the level of the dipstick.[35] This procedure was initiated by Mazda worldwide as a precaution. Mazda did however resolve the issue in the first few months of the engine being available, with the resolution being a software change and a change of dipsticks with a corrected level.[citation needed]
Emission standards and tests
At launch in 2012, Mazda claimed the Skyactiv-D engine would only comply with Euro 5 emission standards (NOx of 0.18 g/km), and further work was required to achieve stricter emission standards.[citation needed]
In the aftermath of the Volkswagen emissions scandal, the Japanese government performed testing of all diesel engines produced in Japan to ensure Japanese manufacturers were not falsifying emissions as had been done by Volkswagen. It was determined that the Skyactiv-D engine was the only engine which tested at or near the standard.[36]
Achieving US EPA emission standards
At the 2019 New York Motor show, Mazda announced that it would commence pre-sales of the 2019 CX-5 with the Skyactiv-D 2.2L engine.[37] To achieve the US EPA emissions standards though has resulted is significant performance and economy penalties in comparison with the Euro 5 compliant engine. The Australian version of the engine is a good comparison with that in the US, with both countries requiring identical diesel quality and using the higher specification of the engine.
The Euro stage V compliant Australian Skyactiv-D 2.2L has the following specifications:[38]
Power: 140kW (190hp) @ 4,500rpm
Torque: 450N⋅m (330lbf⋅ft) @ 2,000rpm
Fuel consumption (Australian ADR 81/02)
Combined 5.7 l/100km (41.3 mpg)
City 6.5 l/100km (36.2 mpg)
Highway 5.2 l/100km (45.2 mpg)
The US EPA compliant US Skyactiv-D 2.2l has the following specifications:[39]
Power: 168hp @ 4,000rpm
Torque: 290lb-ft @ 2,000rpm
EPA Estimated fuel economy:
City 27 mpg
Highway 30 mpg
Recall
In September 2016, Mazda recalled 130,000 vehicles in Japan over a defect that could lead to diesel engine failure.[40]
Although most problems were fixed later on the 2.2 suffered from bad carbon build up that would block the intake manifold. Other faults include the turbo diversion valve failure that required replacement of the complete twin turbo unit.
Mazda recalled 2012 to 2018 diesel Mazda 3, Mazda 6 and CX-5 because of carbon deposits build-up.[41]
Skyactiv-Hybrid
The Skyactiv-Hybrid technology is an electric hybrid engine technology using Skyactiv-G engine with technology from Toyota's Hybrid Synergy Drive, originally licensed for use with the Sky engine for vehicles sold in 2013.[42][43]
The first retail Mazda Skyactiv-Hybrid vehicle, a Mazda3 Skyactiv-Hybrid with Skyactiv-G 2.0 engine with 14:1 compression, was unveiled at the 2013 Tokyo Motor Show.[44][45]
Skyactiv-CNG
The Skyactiv-CNG engine is powered by compressed natural gas.
The first retail Mazda Skyactiv-CNG prototype vehicle, a Mazda3 Skyactiv-CNG Concept, was unveiled in 2013 Tokyo Motor Show.[44][45][46][47]
Skyactiv-R
The Skyactiv-R engine is Mazda's new generation rotary engine. However, the engine has never been shown to the public to prove its existence.
The Mazda RX-Vision Concept, powered by a Skyactiv-R rotary engine, was unveiled in 2015 Tokyo Motor Show.[48]
e-Skyactiv
e-Skyactiv is the battery electric powertrain.[49]
The Skyactiv-Drive is a family of automatic transmissions, named SKY-Drive. Mazda rejected dual-clutch technology in automatic transmissions, because the dual-clutch behavior in certain situations was sub-optimal.[50] Instead, Mazda chose to re-design the conventional automatic transmission, making the torque converter take less duty while a multi-plate clutch disengages the torque converter most of the time. The new Skyactiv automatic transmission was designed to have six gears forward, one reverse gear, a short torque converter and a clutch integrated with the torque converter.[51]
Skyactiv-MT
The Skyactiv-MT is a family of manual transmissions.
To achieve lighter shift effort with a short shift lever stroke, the lever ratio is increased. However, to overcome the shorter internal stroke, a small module spline is used. Shift throws are reduced by 15 percent, making it the shortest shifting of any passenger car.[citation needed]
To allow weight reduction, the triple-shafted gear train is made with reverse and first gears on the same shaft, and the use of a shorter secondary shaft.
Skyactiv-Body
The Skyactiv-Body is a next-generation, lightweight, highly-rigid car body, with improved crash safety performance. The Skyactiv-Body is 8% lighter and 30% more rigid than previous generations.[52][bettersourceneeded]
The compression ratio is the ratio between the volume of the cylinder and combustion chamber in an internal combustion engine at their maximum and minimum values.
The Wankel engine is a type of internal combustion engine using an eccentric rotary design to convert pressure into rotating motion.
The GM High Feature engine is a family of modern General Motors DOHC V6 engines. The series was introduced in 2004 with the Cadillac CTS and the Holden Commodore (VZ).
Mazda has a long history of building its own Diesel engines, with the exception of a few units that were built under license.
Power Stroke is the name used by a family of diesel engines for trucks produced by Ford Motor Company and Navistar International for Ford products since 1994. Along with its use in the Ford F-Series, applications include the Ford E-Series, Ford Excursion, and Ford LCF commercial truck. The name was also used for a diesel engine used in South American production of the Ford Ranger.
The Mazda 6 or Mazda6 is a mid-size car produced by Mazda since 2002, replacing the long-produced Capella/626 in 2002. The car was popular among consumers, selling faster than all previous Mazda models.
The Mazda3 is a compact car manufactured in Japan by Mazda. It was introduced in 2003 as a 2004 model, replacing the Familia/323/Protegé in the C-segment. A performance-oriented version of the Mazda3 was marketed as the Mazdaspeed3 in North America, Axela in Japan, and the Mazda 3 MPS in Europe.
The Mitsubishi Astron or 4G5/4D5 engine, is a series of straight-four internal combustion engines first built by Mitsubishi Motors in 1972. Engine displacement ranged from 1.8 to 2.6 litres, making it one of the largest four-cylinder engines of its time.
Lean-burn refers to the burning of fuel with an excess of air in an internal combustion engine. In lean-burn engines the air:fuel ratio may be as lean as 65:1. The air / fuel ratio needed to stoichiometrically combust gasoline, by contrast, is 14.64:1. The excess of air in a lean-burn engine emits far less hydrocarbons. High air–fuel ratios can also be used to reduce losses caused by other engine power management systems such as throttling losses.
The Mazda CX-7 is a mid-size crossover SUV from Mazda, and is the production version of the MX-Crossport concept car. It was shown publicly for the first time at the 2006 LA Auto Show in January. Production officially began on February 20, 2006 in Mazda's Ujina #2 factory in Hiroshima, and went on sale in April 2006 as a model for 2007. The CX-7 was Mazda's first mid size SUV, since the Navajo was discontinued in 1994.
Homogeneous Charge Compression Ignition (HCCI) is a form of internal combustion in which well-mixed fuel and oxidizer are compressed to the point of auto-ignition. As in other forms of combustion, this exothermic reaction releases energy that can be transformed in an engine into work and heat.
The Honda F-Series engine was considered Honda's "big block" SOHC inline four, though lower production DOHC versions of the F-series were built. It features a solid iron or aluminum open deck cast iron sleeved block and aluminum/magnesium cylinder head.
The Toyota KR engine family is a straight-3 piston engine, designed by Daihatsu, a subsidiary of Toyota. The 1KR series uses aluminium engine blocks and chain driven DOHC cylinder heads. It uses multi-point fuel injection, and has 4 valves per cylinder. Some versions have VVT-i variable valve timing. The engine is exceptionally light: 69 kg (152 lb) with all ancillaries. This is due to the nature of the applications and weight of city cars.
The Toyota KD engine series is a diesel engine produced by Toyota which appeared in 2000.
The Mazda CX-5 is a compact crossover SUV produced by Mazda starting in 2012 for the 2013 model year lineup. It is Mazda's first car featuring its "Kodo" design language, as first shown in the Shinari concept car in August 2010.
The N series is Honda's first automotive diesel engine, an inline-four for medium-sized vehicles. It uses common rail direct injection, which Honda brands as i-CTDi. The most notable feature is the aluminium block, which uses proprietary technology in the manufacturing process to provide light weight and high rigidity. Roller chains drive two overhead camshafts. A variable-geometry turbocharger and intercooler are used.
The DiesOtto motor is an experimental automobile engine that "is said to incorporate the benefits of a diesel engine, but runs on gasoline instead."
The Mazda L-series is a mid-sized inline 4-cylinder gasoline engine designed by Mazda as part of their MZR family, ranging in displacement from 1.8L to 2.5L. Introduced in 2001, it is the evolution of the cast-iron block F-engine. The L-series is used by Ford as their 1.8L to 2.5L Duratec world engine.
The Toyota NR engine family is a series of small inline four piston engines designed and manufactured by Toyota, with capacities between 1.2 and 1.5 litres.
The Suzuki K engine family is a series of all aluminium inline-three or four cylinder automobile engines from Suzuki, introduced in 1994. The displacement is ranging from 0.7 L to 1.5 L. This is a timing chain head driven DOHC 4-valve per cylinder engine with VVT and using multipoint fuel injection or direct injection fuel system.
↑ "Turning Up the Pressure to Keep Gas in the Game". New York Times. November 11, 2011. Retrieved 2011-11-14. But the most daring advance is the 2-litre Skyactiv-G gasoline engine. That 4-cylinder power plant made its North American debut in the 2012 Mazda 3, where it raised the fuel economy rating to 8.5 l/100km in town and 5.8 on the highway with an automatic transmission, from 24/33 for the 2011 model sedan with a 2-litre engine. ...
↑ Pacaud, P.; Perrin, H.; Laget, O. (2009). "Cold Start on Diesel Engine: Is Low Compression Ratio Compatible with Cold Start Requirements?". SAE International Journal of Engines. 1 (1): 831–849. ISSN1946-3936. JSTOR26308324.
↑ Swan, Tony (February 2013). "2014 Mazda 6 2.5L – First Drive Review". Car and Driver. Hearst Communications. Retrieved 2014-04-02. The engineering team nixed a CVT option early on and then decided against a dual-clutch type a little later in the planning process. The reasoning: A dual-clutch automated manual delivers sportier performance, but Mazda felt it was a little abrupt for everyday urban driving. As a result, the new self-shifter is a conventional automatic, with paddle shifters available in higher trim levels.
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